# Low Oil Pressure Still After Teardown 2.0l



## informatted (Aug 2, 2020)

Hello, anyone looking for a puzzle? Because I've been working on my Volkswagen golf mk4 for a couple weeks now but can't seem to find the source of the low oil pressure. Below will be many details, and i'll be sure to keep you guys updated on my progress. I like keeping things short and to the point.
I'm basing my work on the Bentley workshop manual for this engine.
(TLDR: 2002 AVH 2.0L has low oil pressure (checked with manual gauge) and knock from previous owner, (hinted at running it with low oil), checked and replaced the main bearings, rod bearings, oil chain tensioner, and also checked the oil pump and tube which all seem good. No change to low oil pressure and knocking at 1800+ rpm in cylinder 1)

A couple weeks back I bought a 2002 volkswagen golf 2.0l AVH (for $550)
I just wanted the oem roof racks on it but the interior (and ac) all was in great condition and I already have a 2001 same one without ac and crappy interior so figured id pick this up.
It was a trade in at a small dealership (probably saved the previous owner $200 on a used car) and all the guy knew was that it had low oil pressure and would need some work.
I was able to drive it home the couple miles and sure enough the low oil pressure light was on the whole way, but it also has a knock. No overheating issues for the short drive though.

So here I am, tearing into this engine trying to fix it, I don't do everything by the book because im more or less using this as a learning experience (although it would be great if I could get it running properly).

What I've done so far...
Confirmed it has low oil pressure with mechanical gauge (has 5psi at cold idle, dropping to 2 when warm. At 2000 rpm it gets about 15psi, and steadily climes about 8psi per 1000 rpm. Maxes out at 40psi if im lucky.
(Btw my 2001 golf 2.0l gets 40psi minimum at idle)
Changed filter... No difference
Dropped the pan, 2 thrust washers and the timing chain tensioners plastic arm are in the bottom. Along with some silver shavings and some bronze flakes
F..k Me haha
So I changed all the main bearings (they had some major wear on the sides but not to bad on the faces)
Also had to change the center main bearing cap because it has groves for thrust washers, and the driver side thrust washer grove was worn badly.
The thrust washers wore that cap but also wore the block itself, but not as badly. After changing the cap the new thrust washers slid into place and stayed
Take note, I said I found 2 thrust washers in the pan. Both bottoms. Didn't ever find the top ones (which I understand this engine should have, although the Bentley manual isn't specific). 
Either they turned into that metal sludge and flakes, or the engine never had them, or they had been removed during a previous service (which I suspect because the car had new fluids, new water pump, and a new belt tensioner.)
I also changed the oil pump chain tensioner while it was apart. Was hoping I was hearing chain slap as the knocking noise. Nope
Put the engine back together and still low oil pressure and knocking.
Pulled the injector cables on each cylinder and found the knocking was isolated to cylinder 1 (passenger side) and only was audible at around 1800+ rpm. Was louder than the adverage tick of a lifter but because of it only happening on higher rpm I figured it can't be rod knock. Anyways, lowered the pan again.
This time I checked the rod bearings and journals. Seemed okay, but not perfect. Replaced all rod bearings.
Also checked the oil pump pickup, and the pump itself. No clogs and no internal problems. Even hooked it up to the drill and ran some water through it using my finger to plug it and test pressure. Seemed perfect, ran oil through it to rinse the water out. Put everything back together.
Ran engine, still low oil pressure and knocking noise. 
Im now looking into tearing apart the upper half of the engine, but must ask.
WHAT ELSE CAN IT BE?!?!
Here are some things I plan on checking (oil pressure related)
I will diagnose the knock later. Im suspecting piston slap or valves.

Oil pump seemed fine, but maybe the bypass valve or the mating surface to the block is f***ed.
Oil filter flange also has a bypass and check valve, maybe something is wrong there?
There is also an oil cooler bolted onto the oil filter flange. Maybe there is a restriction there.
Lastly could be bad camshaft bearings. Still figured that my oil pressure wouldn't be so low though.
Thanks for any input, good or bad. Engine is partially disassembled right now so feel free to ask questions.


----------



## kgw (May 1, 2008)

Before you tear it down, run an engine flush per the can instructions...Try the LiquiMoly engine flush, drain the oil/filter change, replace the oil. Do it again if you don't get immediate results. :thumbup:


----------



## informatted (Aug 2, 2020)

kgw said:


> Before you tear it down, run an engine flush per the can instructions...Try the LiquiMoly engine flush, drain the oil/filter change, replace the oil. Do it again if you don't get immediate results. :thumbup:


Already have it torn down, but I am planning to do that aswell. The engine only has 100k miles on it so shouldn't be that bad (and initial impressions match that). But I am hoping that if my new oil pump that I have coming doesn't fix the problem then maybe a gallery or something is clogged.
I did end up taking off the oil cooler and oil cooler flange and cleaning both. Nothing out of the normal. Oil flange bypass valve seemed fined, and so did check valve. Also blew air through the oil cooler baffles via a poly tube and my lungs and air passed easily, no back pressure indicating a blockage.

I'll check the bearing tolerances again probably once I get the new oil pump.

So my check list has come down to either something i've done hasn't been done correctly or 
Some oil gallery is plugged, cam shaft journals are piss, or oil pump is bad.

Crossing my fingers that once/if I fix the low oil, the knocking will go away aswell. But it is pretty loud so not sure. Not as loud as rod knock though, almost certain it is piston slap. But from the bottom, cylinder one seems fine.


----------



## informatted (Aug 2, 2020)

Also, does anyone know if the thrust washers contribute to the oil pressure. They aren't thrust bearings and main purpose are to support the axial motion of the crankshaft but was wondering if they also greatly impact the oil pressure. I've heard some people have run their engine without them completely. 

Also maybe I shouldn't have included the upper thrust washers as they haven't been included in the picture of the manual. But it says arrangement may differ from illustration, plus the kit for my engine came with them. Plus they seemed to have a spot.


----------



## garryt (Dec 22, 2016)

if you have narrowed it down to cylinder one, then the big end journal might be damaged. it could be piston slap. but with oil pressure that low, I would be looking elsewhere.


----------



## informatted (Aug 2, 2020)

garryt said:


> if you have narrowed it down to cylinder one, then the big end journal might be damaged. it could be piston slap. but with oil pressure that low, I would be looking elsewhere.


Already replaced all the main bearings and rod bearings. Journals all looked fine enough but i'll double check once I put the new oil pump in.


----------



## Sagginwagen (Oct 15, 2018)

Have you tried cleaning or replacing the oil pressure relief valve? 

053103155E
#19 in picture











Sent from my iPhone using Tapatalk


----------



## informatted (Aug 2, 2020)

*Yes and no*

I don't think that is the same engine as mine. My oil pressure releif valve is located on the oil filter flange, and one on the oil pump itself. I put a brand new oil pump on and checked and cleaned the valve on the flange. Still same problems.


----------



## informatted (Aug 2, 2020)

Update: Still broken
Just threw in a new oil pump, checked and cleaned the oil filter flange (checked the check valve and relief valve, both seemed fine). Also replaced the oil cooler located on the oil filter flange. 
Also threw a new cam shaft in since the old one had a little scouring, even polished the camshaft caps.

Thinking about calling it quits, out $500 could of bought a new used engine


----------



## informatted (Aug 2, 2020)

Seems I have gotten the pressure bypass valve confused with the relief valve. Would the relief valve cause low oil pressure though?


----------



## Sagginwagen (Oct 15, 2018)

Yes, if it is stuck open. 


Sent from my iPhone using Tapatalk


----------



## informatted (Aug 2, 2020)

Here is my engine btw


----------



## informatted (Aug 2, 2020)




----------



## Sagginwagen (Oct 15, 2018)

Sorry about that. I should have payed closer attention to my search results.


Sent from my iPhone using Tapatalk


----------



## garryt (Dec 22, 2016)

informatted said:


> Seems I have gotten the pressure bypass valve confused with the relief valve. Would the relief valve cause low oil pressure though?


pretty sure they're the same thing.


----------



## Sagginwagen (Oct 15, 2018)

^ i think you’re right. But isn’t the bypass valve for if the filter is clogged? The pressure relief valve regulates pressure at the pump? 


Sent from my iPhone using Tapatalk


----------



## garryt (Dec 22, 2016)

Sagginwagen said:


> ^ i think you’re right. But isn’t the bypass valve for if the filter is clogged? The pressure relief valve regulates pressure at the pump?
> 
> 
> Sent from my iPhone using Tapatalk


you could be right. tbh iv'e not had much to do with them newer engines.


----------



## informatted (Aug 2, 2020)

garryt said:


> you could be right. tbh iv'e not had much to do with them newer engines.


yeah upon double checking I think all the valves serve a similar purpose.
My guess now is the camshaft caps and guides are bad. Sadly there are no camshaft "bearings" because the cap and other side on the head act as a bearing. Which means id need to replace the whole head if that's the problem.
All the caps looked pretty ruff with cap 2 and 4? being the worse. I polished them all down but clearance might be to tight.

what I believe happened to this engine was the thrust washers wore lose, then the metal went through the whole engine, fking up all the bearings. I should just get a new engine but im so far into this plus don't have the tools to drop and lift a whole engine, so I can only work in parts.

I might go get a used head and cam.
Pressure seems to be about 20% better when cold after I polished the caps, new cam, new pump, and new oil cooler. But I did them all at the same time so im not sure which part actually improved my pressure. Although it still drops to 2psi at idle when warm (boost to about 10psi per 1000rpm though when revved)

My guess is polishing the cam caps boosted the pressure.


----------



## garryt (Dec 22, 2016)

I think one of them valves will just be an anti-drain back to keep the oil up in the engine when not running.


----------



## Butcher (Jan 31, 2001)

Those oil pressure relief valves are for the piston oil nozzles. Once the oil pressure gets to a certain point, the valve will open and oil will be forced to the bottom side of the pistons. There is one per nozzle. One nozzle per cylinder. They also hold the nozzle to the block. Basically its a hollow bolt with a ball/spring that will break away at a certain pressure. 

Yes, it's an oil pressure release valve, but nothing to do with the lubrication system. 

Oil pressure is caused by the restriction of the oil passages. The more restriction, the more pressure. Pumps do not make pressure, they just push the oil. The restriction is why there is pressure. That said, if the bearing clearances are too large, then the restriction is less and so is the oil pressure. Scored cam journals is a problem. If your trust bearings were no good, I would have a hard time believing that if you installed new ones that the thrust spec is in spec.


----------



## garryt (Dec 22, 2016)

Butcher said:


> Those oil pressure relief valves are for the piston oil nozzles. Once the oil pressure gets to a certain point, the valve will open and oil will be forced to the bottom side of the pistons. There is one per nozzle. One nozzle per cylinder. They also hold the nozzle to the block. Basically its a hollow bolt with a ball/spring that will break away at a certain pressure.
> 
> Yes, it's an oil pressure release valve, but nothing to do with the lubrication system.
> 
> Oil pressure is caused by the restriction of the oil passages. The more restriction, the more pressure. Pumps do not make pressure, they just push the oil. The restriction is why there is pressure. That said, if the bearing clearances are too large, then the restriction is less and so is the oil pressure. Scored cam journals is a problem. If your trust bearings were no good, I would have a hard time believing that if you installed new ones that the thrust spec is in spec.


I don't think the thrusts affect oil pressure. they're just there to cushion the load from pressing the clutch in and out.


----------



## Butcher (Jan 31, 2001)

I would agree. They are not pressure fed so I would have a hard time believing that they would effect oil pressure.


----------



## garryt (Dec 22, 2016)

they shouldn't really. but if the crank has been jolting back and forth, the bearings could be damaged in some way.


----------



## informatted (Aug 2, 2020)

And they were. I had to replace all main bearings because of significant metal fragmentation on the sides of the bearings. The rod bearings looked fine but replaced them just in case.
I also doubt the oil jets have anything to do with my low oil pressure. I picked up a new head from the scrap yard that looks to be in great condition. Now I just need some time and motivation to put it on. 
This will be the 4th? time ive tore into the engine trying to fix the problem.

I think the new head will fix the oil pressure problem because I suspect the camshaft journals and caps are the source of low oil pressure. It annoys me that they don't have removable bearings that I could replace. 
The knocking still worries me but i'm hoping that a new head magically fixes it? I'll take a look at piston 1 and see if there are obvious problems and if i'm smart I will pull it out, but I doubt it.

Another question/concern.
The rod journals and caps have bearings (duh), but those bearings don't have a tang to keep them in place. Why would a company do this? (The journals and caps don't have a groove for the bearing tangs either so it is suppose to be like this I know).
At least the main bearings have one.


----------



## Butcher (Jan 31, 2001)

Why would a company do this?

One thing you should do, is give them the respect that they've earned. You may not believe this, but they know way more about that engine than you ever will. Once you give them that respect, then you will understand there are different ways to accomplish a task. I suggest that you embrace the new technology. I used to be just like you and complained regularly. Now that I have drank the Kool-aid, it's much easier to fix cars. 

They no longer need the tangs because they have enough crush to keep the bearings from moving around. Since that is the purpose of the tangs and they figured out that they do not need them. The money saved from additional machining can be used for something else. Same way with the cam bearings. It's money saved by not having bearings. 99.9% of the heads will last long enough that they will never wear out. Yours are not worn out, they are damaged. 

I'm really puzzled that you have a knocking noise and you are not going to figure out the cause of this noise. My crystal ball shows an engine being taken apart a 5th time or maybe another engine is being installed. Still pretty cloudy. 

Maybe doing by the book may be a good idea isn't that bad of an idea?


----------



## informatted (Aug 2, 2020)

Butcher said:


> Why would a company do this?
> 
> One thing you should do, is give them the respect that they've earned. You may not believe this, but they know way more about that engine than you ever will. Once you give them that respect, then you will understand there are different ways to accomplish a task. I suggest that you embrace the new technology. I used to be just like you and complained regularly. Now that I have drank the Kool-aid, it's much easier to fix cars.
> 
> ...


I took the engine apart multiple times in search of low oil pressure, with the first fix being the main bearings and thrust washers because they had obvious damage. I checked everything else during that first fix and it was all up to spec. Once that didn't fix the problem I decided it best to replace the rod bearings, pump, tensioner, oil cooler, and check the oil filter flange since those all could of been affected.
I'm taking this as a learning experience, not necessarily on how to fix the engine, but on familiarization on what each thing does and how it all links together. I'll tell you something, I can tear this engine down in record speed now. The only part that frustrates me is getting the timing belt on, usually takes me longer than everything else combined.

Anyways, once I was done messing with the bottom end, and still had low pressure I had 2 resort to looking at the top end. 
I'm running on a tight budget, currently not working with plenty of free time so not exactly doing all the preventative maintenance and that jazz, just what I see as broken and will need fixed. Unless the part is dirt cheap and easy enough to replace.

Now that I have tore into the top, I realize it isn't that bad to work on. So threw a new cam in and polished up the caps crossing my finger that it would fix it. Of course it didn't, but I didn't expect it to really. Did see a slight improvement which gives me the motivation to replace the head.
Grabbed a niceish used head from the scrap yard the other day and will be installing it once my new gaskets come in a week.

And yes, the knocking still worries me, but it definitely isn't rod knock and I suspect it is piston slap but could easily be wrong. The thing is it happens when revving up at about 2000+ rpm and above, while engine is cold and warm. I have it isolated to cylinder one and it seems to decrease or go away when the fuel injector or plug wire is pulled.
I checked from the bottom and the piston, walls, and everything looked fine. Also has good compression. So im hoping it is something with the valves or something that will make itself evident once I pull the head.


----------



## informatted (Aug 2, 2020)

Also, im getting the new used head ready for install and noticed the cylinder one has more carbon buildup on the valves and in the exhaust port. All 3 other exhaust valves have clean stems when looking through the exhaust port but the 1st one has carbon buildup on the stem.
Im assuming that this is either rich fuel or oil. If it was fuel it would likely be on all valves, so judging this im leaning towards oil. And the source of oil would be a leaking valve guide seal?


----------



## informatted (Aug 2, 2020)

Here is a video of the knocking. Any guesses?


----------



## Butcher (Jan 31, 2001)

My $.02. That knock is deep. Not pistons and I suspect loose rods. Did you plastigage the bearings? I doubt if that noise is anything related to the cylinder head or any of its components. That is not piston clearance issues either. With bearings that were seized, maybe the oil port in the crank is blocking off the oil supply to the rod. 

Do as you wish because I know you have financial and time issues, but I would be looking for another engine to learn from.


----------



## informatted (Aug 2, 2020)

Butcher said:


> My $.02. That knock is deep. Not pistons and I suspect loose rods. Did you plastigage the bearings? I doubt if that noise is anything related to the cylinder head or any of its components. That is not piston clearance issues either. With bearings that were seized, maybe the oil port in the crank is blocking off the oil supply to the rod.
> 
> Do as you wish because I know you have financial and time issues, but I would be looking for another engine to learn from.


When you say loose rods, what do you mean? I replaced and checked all rod bearings so they definitely aren't loose.
The knock is isolated to piston/cylinder 1. Also the bearings never seized. Just the main bearings received damage from shifting due to bad thrust washers. 
Could there be a problem with the wrist pin in cylinder 1 causing that knock? Otherwise im still suspecting piston slap. I wonder if the crankshaft has shifted to far forward or back causing the piston to not be centered. Either way youd think more pistons than just cylinder 1 would be making noise. I suspect once I pull the head in a few days i'll have my answers. Although if it is the wrist pin then i'll have to take the pan back off.


----------



## Butcher (Jan 31, 2001)

Upper rod bushing. 

The crank moves forward but the pistons does not. So the crank rod journal travel would not match the piston rod journal travel. Something has to give for this to work. That leaves the rod, rod bearing, upper rod bushing, or piston. Since you had the head off, I suspect that you checked the cylinder bores, if not, then it's certainly wise to do that. Maybe it would be a good idea to measure the bore to check if it's out of round.

I'm suspecting that the upper rod bushing is the problem because it has a lot of load in a smaller surface area. Should be simple to check. Unbolt the rod and see is you can twist it or pivot it side to side. Within reason, you probably should not feel any play.

When you say you checked something, you may want to elaborate on what you did. When you say new, is it new? New used part? For instance, you mentioned you checked the pistons. My idea of that is certainly different than yours. If you did check them like you should, then you would not ask yourself if this is pistons slap. Your measurements would prove that.

How would piston slap cause low oil pressure? I can't think that it would. 

Remember, you are working on an engine that needed a complete rebuild. That would mean you would have new pistons, bearings, and a huge machine shop bill. You are going about this like you have a love affair with this engine. There are many more engines just like this that are much less time/money consuming than the one you got. I would look for another one.

Sounds like I'm talking about your girl friend.


----------



## informatted (Aug 2, 2020)

Butcher said:


> Upper rod bushing.
> 
> The crank moves forward but the pistons does not. So the crank rod journal travel would not match the piston rod journal travel. Something has to give for this to work. That leaves the rod, rod bearing, upper rod bushing, or piston. Since you had the head off, I suspect that you checked the cylinder bores, if not, then it's certainly wise to do that. Maybe it would be a good idea to measure the bore to check if it's out of round.
> 
> ...



Haha,
well I actually just got the head off today, I have a junkyard head that i'll be replacing it with. The car at the yard was scrapped due 2 a broken drive shaft, engine was in good condition.
When I say I checked the pistons, i'm referring to when I had the crankcase off. I just did a visual check and tested for obvious play. Everything seemed fine, and also everything seemed the same for all 4 cylinders.
There are 2 problems, the low oil pressure and the knocking. I'm not saying the knocking was causing low oil pressure, sorry for the confusion. The knocking is a problem separate but could of been caused from damage due to low oil getting to the rod or I even thought there was a slight chance it was still lifter knock. 

Im replacing the head just because of the damage to the camshaft bearings, which are part of the head and not separable. 
Just got the head off today, and the head of the pistons all seem fine as well, so i'll probably drop the pan and pull out cylinder one's piston and check further. I assume you are correct when suspecting the piston pin being the problem (you referred to it as the upper rod bushing). 

Sum things up: I will be getting the junk yard head ready for install, I have to replace the valve stem seals on cylinder 1 (and all others but) because it seems there was excessive carbon on the exhaust valve for that cylinder which I assume was a leaking seal.) Then I will be lowering the pan again and checking the oil spray jets for problems and also check the oil galleys by blowing some compressed air and pushing a plastic coated steel wire through. Then I plan on removing the piston from cylinder one and checking it all over and probably throwing in a known good used piston and rod. Will also check the cylinder more in depth. I will then clean off some carbon and reassemble everything.
If that doesn't fix the low oil pressure and the knock then I will call it quits. No worries, I learned a lot. Last thing I might try is swapping injectors and checking all the timing system again to make sure it isn't preignition or something causing spark knock.

Anyone have any other tips or thoughts? Feel free to leave some input. Once my valve spring compressor comes in tomorrow I will be slowly doing these things over the next few days.


----------



## EPilot (Jul 27, 1999)

Did you do a compression test on the engine at all? 

Still not sure why you just don't get a used engine and be done with it. 2.0L's are easy to find and relatively cheap.


----------



## garryt (Dec 22, 2016)

informatted said:


> Haha,
> well I actually just got the head off today, I have a junkyard head that i'll be replacing it with. The car at the yard was scrapped due 2 a broken drive shaft, engine was in good condition.
> When I say I checked the pistons, i'm referring to when I had the crankcase off. I just did a visual check and tested for obvious play. Everything seemed fine, and also everything seemed the same for all 4 cylinders.
> There are 2 problems, the low oil pressure and the knocking. I'm not saying the knocking was causing low oil pressure, sorry for the confusion. The knocking is a problem separate but could of been caused from damage due to low oil getting to the rod or I even thought there was a slight chance it was still lifter knock.
> ...


have you tried running it with the aux belt off? sounds a bit like alternator bearings to me.


----------



## informatted (Aug 2, 2020)

Yup, it is amazing how easily an engine revs with the accessory belt off. But this did not fix my problem.
Only thing that fixes the knocking is pulling spark or fuel injector wire from cylinder 1.


----------



## informatted (Aug 2, 2020)

EPilot said:


> Did you do a compression test on the engine at all?
> 
> Still not sure why you just don't get a used engine and be done with it. 2.0L's are easy to find and relatively cheap.


Engine has good compression, 180s all around.
I could have bought a whole new engine but I like the learning experience. This isn't my daily so I got time for experimenting. Also I already put some work into it so why not just finish what I started


----------



## garryt (Dec 22, 2016)

informatted said:


> Yup, it is amazing how easily an engine revs with the accessory belt off. But this did not fix my problem.
> Only thing that fixes the knocking is pulling spark or fuel injector wire from cylinder 1.


ah yes. I just re-read your original post. you say the rod bearings seemed okay, but not perfect? when you are working with clearances of about 1 thou, things really need to be perfect. if one of the big end journals looked marked/scored in any way, that's not good news.


----------



## informatted (Aug 2, 2020)

garryt said:


> ah yes. I just re-read your original post. you say the rod bearings seemed okay, but not perfect? when you are working with clearances of about 1 thou, things really need to be perfect. if one of the big end journals looked marked/scored in any way, that's not good news.


Original engine had 100,000 miles and the rod bearings looked as such. Definitely still good but I replaced them anyways. Yes the main bearings all had been damaged on the sides due to the thrust washers falling out of place. The actual wear on the main bearings looked fine but the sides had become jagged so I replaced them and replaced the thrust washers of course.

I got the head off the other day and it all looks fine besides the camshaft bearings of course. I think that is the source of my low oil pressure. So I have a new/used head that I'm putting new valve seals in and prepping to bolt on.

My big concern now is the knocking because i'd hate to tear the top end apart again. Bottom end is peace of cake, top not so much.
I removed the piston from cylinder one and from my untrained eye everything looks fine. No real polished areas or anything on the cylinder walls. I don't have the expensive tools to check exact diameters but there are no obvious problems. The piston itself seems okay aswell, has some wear but very little I think. There is a slight polished area on the underside of the piston where the wrist pin and connecting rod meet. Suggesting that the rod is sometimes shifting over to one side and rubbing. This could be my knock. Although the polished area is very shallow and not that large so i'm not confident. I'll try to provide some pictures.

So the big question is still, what is causing the knock? I really don't want to put the head back on without finding a clear source of the knock. But might have to.


I'm going to measure piston ring gap and make sure that's good, and also probably pull piston 2 and compare it to 1 as a way to double check appearance since the knock is only cylinder 1. 

I mentioned earlier that the very first time I opened the crankcase to find out the source of low oil pressure and the knock there was 2 bent thrust washers in the oil pan which I have replaced. These thrusts washers did cause scouring to the crankshaft main bearing cap and engine block but the new ones still slid into place and have stayed for the few minutes after each assembly and test of oil pressure and knock. I'm wondering if there can be excessive crankshaft play under load that is causing the knock (maybe piston slap like I suspect). But why would it only be in cylinder 1? That is why I don't think its the case. 

I'm thinking of typing up a clean thread with pictures and documentation of all my trials and errors to make it easier for newbees to find answers.
Update: Piston 4 has same signs of wear as piston 1. Including the slight polish on one side of the inside wrist pin/connecting rod area.
Note: Knock was isolated by pulling spark, and fuel to cylinder 1.


----------



## informatted (Aug 2, 2020)

This all looks like normal piston wear after 100,000 miles to me. I assume it doesn't need replaced. What do you guys think?









There is a very slight polished area on the underside of the piston by the wrist pin. This showes the connecting rod is rubbing here. But it is only on one side and it isn't a groove, just a polished area. Is this the source of my knocking and what is causing the rod to not stay centered?


----------



## garryt (Dec 22, 2016)

informatted said:


> This all looks like normal piston wear after 100,000 miles to me. I assume it doesn't need replaced. What do you guys think?
> 
> 
> 
> ...


the piston coating looks fairly worn. as for the rod rubbing it, that probably happened when the thrust washers failed (the crank would have moved forward taking the rod with it slightly) is there any play between the rod and piston?


----------



## garryt (Dec 22, 2016)

I have a set of them exact pistons and the wear on the coating is about 1/2-5/8 inch circle right in the middle. but they could be a much lower mileage. I bought them already parted out.


----------



## garryt (Dec 22, 2016)

get some pics of the bearings up:thumbup:


----------



## informatted (Aug 2, 2020)

garryt said:


> get some pics of the bearings up<img src="http://www.vwvortex.com/Anthony/Smilies/thumbup.gif" border="0" alt="" title="Thumb Up" class="inlineimg" />


What bearings would you like to see, I've already replaced the main bearings and rod bearings so pictures wouldn't help much unless I did something wrong lol.
I still have the old bearings somewhere.

As for play, I assume the play I notice is normal. That being, the connecting rod slides freely on the wrist pin and there is no play in other directions. And when the connecting rod is mounted to the crankshaft there is about 1 mil if not less of play left to right and none up and down.
The play I measured is also the same for the other 3 cylinders. I'm just hoping to find a difference between something in cylinder 1 and the others but can't find anything. I wonder if it is spark knock or something with timing. I'm going to hold off and do a little more research before I put the new/used head back on.
I might try to switch the injector from cylinder 1 into cylinder 4 and see if that makes a difference. And also I think there are 2 knock sensors on the front of the block, I wonder if that could cause my problem. Might switch them aswell to see if there's a change. Doubt it though because no codes have been thrown. 

Also I beg to differ on the wear of the pistons. From what I think, wear would show itself as a polished area or discolored area. While it is discolored a bit I think that is minor and the fact the pistons still have machine marks indicated they are in really good condition. 
It is weird that this engine has 100,000 miles with very little carbon or oil sludge. I'm thinking someone might have dons a flush or cleaning in the past 🤔


----------



## Butcher (Jan 31, 2001)

With proper oil services with good oil, there should be no sludge. It's weird that people are too cheap/lazy to get that done. 

So far, what you have written are not tests. I believe you have good intentions but the way you checked the bearings is not a way to check bearings. Then you use your test results as fact to make a decision. The tests you are making are worthless. It's like kicking a tire and telling yourself it's good.

Spark knock? I think you need to read up on the definition of the meaning. 

Way too many assumptions going on here. You have a Bentley. I suggest you perform tests exactly how they say to. You'll have better information to make better decisions.


----------



## informatted (Aug 2, 2020)

Butcher said:


> With proper oil services with good oil, there should be no sludge. It's weird that people are too cheap/lazy to get that done.
> 
> So far, what you have written are not tests. I believe you have good intentions but the way you checked the bearings is not a way to check bearings. Then you use your test results as fact to make a decision. The tests you are making are worthless. It's like kicking a tire and telling yourself it's good.
> 
> ...


Not sure what exactly you mean, maybe you missed it but I have checked all bearings with plastigauge and the cam and main needed replaced with the connecting rod bearings being within spec but replaced anyways. I've isolated the knock to cylinder 1 by pulling spark and fuel. Now my goal is to fix the low oil pressure (which I believe the new head with new cam bearing surfaces will fix) and to fix the knock (which is still undetermined the cause or source).

I also have doubts sit is spark knock as well because I have checked the timing, fuel, and also checked for any excessive carbon deposits or damage on the piston crown or cylinder head that could cause a difference in ignition. Everything seems fine leaving me to believe it isn't spark knock. But cant hurt to swap the injectors to make sure the problem doesn't lie there. And swapping the knock sensors would also rule a problem there out. Again I don't think that is the problem but I can't be 100% sure.

My hunch was there being piston slap due to excessive wear in the cylinder or piston (maybe wrist pin) but after checking that it seems that is not the case, if there was piston slap then there would be a polished area on the lower skirt of the piston as it slaps against the cylinder wall.
But this doesn't leave many more options for what is causing the knock. 
I'm going to try and check crankshaft end-play but you'd think that would cause a problem in multiple cylinders.

Remember, I don't have all the fancy tools and such I have to make do with what I got or can buy for a reasonable price and have in a day or two. If I can't fix it, no harm done. But I'd like to try.


----------



## Butcher (Jan 31, 2001)

informatted said:


> maybe you missed it but I have checked all bearings with plastigauge and the cam and main needed replaced with the connecting rod bearings being within spec but replaced anyways


I skimmed thru your thread and I did not see where plastigage was mentioned. 

The rod should not be hitting the side of the piston. Did you take the wrist pins out? Did you check the bushings? The rods are kept inline by the crank. When the thrust bearings were worn out, the crank could have pushed all the rods with them. It also could be that the rod is slightly bent. Have you checked the piston height?

It's not spark knock. Not certain why that would even be brought up.


----------



## informatted (Aug 2, 2020)

Butcher said:


> I skimmed thru your thread and I did not see where plastigage was mentioned.
> 
> The rod should not be hitting the side of the piston. Did you take the wrist pins out? Did you check the bushings? The rods are kept inline by the crank. When the thrust bearings were worn out, the crank could have pushed all the rods with them. It also could be that the rod is slightly bent. Have you checked the piston height?
> 
> It's not spark knock. Not certain why that would even be brought up.


Spark knock was brought up as a possibility because, well it is a knock. And I figured there is a chance that it is something other than rod knock because all the rods and bearings have been checked. But that is rod knock in the up and down direction mainly. I inspected the piston, pin, rod, bearings, cylinder wall, travel, and it all seems to be in spec. The only thing out of spec would be crankshaft end play. Because of the damage caused by the old thrust washers failing there is now a slight groove which means more travel. Now before everyone jumps on this, you have to ask yourself, would this cause a knock in just 1 cylinder. Now anyone can speculate how it might, I just want to know if anyone has experience with such an occurrence. I understand this play should be fixed before I continue, but is it likely the cause of the knock?

Also as a quick summary, my guess is it seems that the thrust washers failed due to some event, whether a manufactured error, or likely owner error. This caused them to scour a groove in the main bearing cap and engine block, eventually falling out and getting beat up in the bottom of the pan. This lack of thrust washers also caused the main bearings to shift and tear the sides of the main bearing surfaces. Some of this metal then was circulated through the engine causing scouring. The damage probably caused a lack of oil pressure which resulted in the camshaft not getting proper lubrication and resulted in the bearings having significant scouring and wear. Somewhere in all this the cylinder 1 developed a knock.

Looking at the engine internals and wear you'd think the engine is under 50,000 miles because everything else seems nice and clean, with little wear.

To fix all these issues I have replaced the oil pump, main bearings, rod bearings, center main bearing cap with thrust washer grooves, thrust washers, and will be throwing on a better condition head with newish cam bearing surfaces, and a new cam.


----------



## garryt (Dec 22, 2016)

did you swap a main bearing cap from another engine?


----------



## Butcher (Jan 31, 2001)

informatted said:


> To fix all these issues I have replaced the...... center main bearing cap with thrust washer grooves,.....


I really believe you are way over your head and what you think you know about engines is far from right. 

The main caps are all machined at the same time when the block is machined. You cannot just swap caps and expect the machining surfaces to be correct. That includes swapping them from another engine block. I do not understand why you would think this is ok except to think you really do not have a clue what you are doing.

You also do not know what spark knock is. Spark knock occurs when the combustion is occurring before the spark plug has fired or that the spark has occurred way too soon. So the combustion is happening while the piston is coming up. The piston is forced down while the crank forcing it up. This is why there is a noise. It just does not happen on a normally running engine. I've seen it before, but usually the engine is almost melting down because it's overheating.

Now anything can happen but at idle this is darn near impossible. There is so little air/fuel mixture to burn it's just not going to auto ignite. 

By now you really think I'm as Ahole because I'm just pointing out what I'm reading. We all start somewhere near clueless and at some point in life, some become knowledgeable. Just because you are clueless now, does mean you will still stay on that spot. What I'm getting at is that you are coming up solutions based on your lack of experience. Then you think those solutions are good. I do this for a living and Ive been there before. I've assumed how something works and it's not until I research the problem that I find my assumption was wrong. This is where you are at right now. Again, we all run into this in life. The ones that figure it out first are the ones that accept they have no clue what they are doing and stop thinking they do.

You need to come up with solutions based on facts. Looks good, fine, ok, etc are not specs. They never have been and never will be. Give us some clearance numbers. Be it metric or standard, something we can go by. It's frustrating that people say that and since they believe it's good they make a decision. If it was good, you would not have this problem. You say everything is good and it seems that you refuse to make a good test to prove it's good or not.

When you checked the oil clearances, did you check the crank? And before you did, the only way I know how to check it is to drill the plugs out and clean out the debris. Since the crank bearings feed the rod bearings, I suspect that debris may be in the crank causing a restriction. Since you cannot check for that without drilling the plugs, don't say they are good until you remove the plugs.


----------



## garryt (Dec 22, 2016)

Butcher said:


> I really believe you are way over your head and what you think you know about engines is far from right.
> 
> The main caps are all machined at the same time when the block is machined. You cannot just swap caps and expect the machining surfaces to be correct. That includes swapping them from another engine block. I do not understand why you would think this is ok except to think you really do not have a clue what you are doing.
> 
> ...


iv'e only come across one of them cranks once (the one with the ball bearings staked in) was from a mid 80's audi 80 1.8. didn't think they were still done that way you never know with the swapping main caps from another engine. machining seems to be far more accurate in recent times. might just get away with it. pull the cap and check the shell now. if it's not lined up well, it will show up as obvious wear on one side:thumbup:


----------



## informatted (Aug 2, 2020)

Butcher said:


> I really believe you are way over your head and what you think you know about engines is far from right.
> 
> The main caps are all machined at the same time when the block is machined. You cannot just swap caps and expect the machining surfaces to be correct. That includes swapping them from another engine block. I do not understand why you would think this is ok except to think you really do not have a clue what you are doing.
> 
> ...


Yikes, let me put it this way... I am trying to get this engine running without a knock and low oil pressure. I am not aiming to make this engine last another 100,000 miles and not aiming to make it show room quality, or even daily driver quality. I just want to see if I can figure out the 2 problems it has.
When I don't include specs it is because they are within the spec listed in the Bentley manual, so it would redundant to say "the main bearings are within spec, and that spec is 0.01-0.04 mm (.0004-.0016 in.) new with a wear clearance of 0.15 mm (.0059 in.) and my bearings have a clearance of .0016in."
I do know what spark knock is, but I am not familiar with the sound of spark knock. When you say it doesn't happen on a "normally running engine" well, this isnt normally running. Also you say it usually results in engine overheating,I haven't ran the engine for any good period of time so can't rule that out as a possible symptom either. And you say spark knock is unlikely at idle, well my knock isn't at idle, it is when revving up or higher rpms mentioned earlier. So no offense, I believe you mean well, but please don't discredit any knowledge I have even if it isn't 100%, i'm just trying to learn.

I have checked oil clearances at all bearings, now your question as to the possibility of a plugged galley is definitely sound. I have thought this and mentioned it earlier, but no, I haven't drilled into the crank and likely wont be doing that... but it is something I should check thoroughly I agree, but don't want to go through that investment. 

For the question about switching the main cap, yes I know that they are all matched and unique to the engine because they are line bored together and interference fitted. So I took a gamble with grabbing a random good condition on from the scrap yard and throwing it on. Now I know what your'e thinking "omg this idiot" and I agree it isn't the best option and I should send the engine and caps to the machine shop to be line bored and fitted. But if I was going to go through that trouble than I would have just gone with the whole new engine. Plus lets just speculate a little here, these parts are manufactured with precision and therefor do not differ by much, hence the reason they can be rebored without taking off much material. Now the one I grabbed is from the same plant (based on the stamped factory markings) and I of course did spin the crank over with it installed. What do you know it did not seize up and after running the engine for 10 minutes or so I checked wear on the bearing and it was very uniform. So I dont think this new center cap has any impact, plus the knock was there before I replaced it.
So maybe now you can understand that I do know what im doing to some extent, whether I purposely choose the worst of 2 options or not. There is a reason behind all my decisions. And most of the reasons are either to prevent taking the whole engine out, sending it to a shop to be machined, or getting a new engine.
If it makes you feel any better I have another 2.0l that runs just fine, but I wan't to see if I can get this one running without a knock and with good oil pressure for my own satisfaction. Plus I believe the best way to learn is hands on and through ones mistakes. 
Now if this was a car I cared about, I would 100% do everything by the book and do it right. But.....


----------



## informatted (Aug 2, 2020)

Also understand when I differ from providing readings for things like piston diameter and instead refer to it as looking very good and what not it is because it obviously is within spec showing no signs of wear so would be frivolous to measure it and then update saying "yup it was within spec, makes sense because it has no wear at all"

Now I don't mean to sound like im discrediting anyone's knowledge or anything, and sorry if anything came across in the wrong way. All help is appreciated and that is why I have posted to this forum, I don't mind any constructive criticism. At the end of the day, we all might learn a thing or 2.
So again thank you for your input, and feel free to keep up with and updates I provide. Cumulatively our knowledge is much more than individually. (Although I might only be contributing 10% of that knowledge :laugh


----------

