# I pulled my pistons...look at these pics and YOU tell me:



## nater (Apr 10, 2000)

Guys,
You all probably know what my deal is...
So, I pulled the pistons and here's what I found:

The least marking/scuffing seams to look like this:









The most scuffing seems to look like this:








Both of the above pics are taken of the BACK part of each cylinder. There seems to be hardly any scuffing on the front part of each piston/cylinder.
What is weird is, the picture just above is from one of my front three cylinders (where my compression readings were HIGHER than the rear).
The rear cylinders had less scuffing.
Here's more pics:
from one of the rear cylinders









Don't know which cylinder this is, but it's a pic of the rings and how the side of each piston looks like (they all look like this).
Also, each piston ring moves about freely and there is no "welding" of the ring to the ringland or skirt.









Again, they all pretty much look like this:









And all look identical to this underneith:








I see nothing melted at all. Tops of pistons you can see from my other thread : http://forums.vwvortex.com/zerothread?id=2025263

Help?

PS: I hope these pics work, b/c my monthly data transfer ran out but the billing cycle starts today....
If you see red x's please be patient while my service "resets" back to zero bandwidth transfer.
Later,


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## 2kjettaguy (Dec 24, 2000)

*Re: I pulled my pistons...look at these pics and YOU tell me: (nater)*

Top picture and second picture from the bottom - notice the sides of the rings are pitted from detonation. Not good. 
Any pictures of the tops? Not cleaned off in any way, fresh from the engine... 
Evan


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## nater (Apr 10, 2000)

*Re: I pulled my pistons...look at these pics and YOU tell me: (2kjettaguy)*


_Quote, originally posted by *2kjettaguy* »_Top picture and second picture from the bottom - notice the sides of the rings are pitted from detonation. Not good. 
Any pictures of the tops? Not cleaned off in any way, fresh from the engine... 
Evan 

Evan,
I'm not sure if it's something to do with how I took the pics but those rings are smooth as silk. I just took my thumb to each of them and wiped off dirt and stuff...came off clean and smooth. No pitting. am I missing something? 
As far as pics...This is taken direct from the thread I mentioned in my first post....I hope there aren't any dial-up guys here







:



















































































































Later,


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## nater (Apr 10, 2000)

And how about the scuffing? 
Not normal?
Later,


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## 2kjettaguy (Dec 24, 2000)

*Re: (nater)*

Nate - if it's just the pics then perfect. The pictures make the rings looks pitted, which is weird but bad! Smooth is good. 
Your piston tops look pretty good. Maybe a little lean in some spots. How long did you drive on the boost spikes? The more golden areas of the piston look like they have been steam cleaned. This look is synonymous with detonation or a lean condition. I had 4 clean, golden pistons when I smoked my motor. 
I don't see any pitting in the piston tops or head, so I think you're OK as fas as detonation goes. 
The scuffing? I am little confused myself. It could be a couple things... there's actually a little debate going on about this in another 1.8t forum. A guy just smoked a set of pistons with what he thinks to be too close of a gap. They are ruined, and he lost compression. I can link you if you want to compare pictures. 
Too much heat can cause the pistons to expand and make contact with the walls. Poor bore / piston diameter clearances can also be the cause. 
However, I am no expert and I didn't build the motor. I don't want to speculate too much. Have you shown these to Bill Schimmel yet? 
Evan


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## nater (Apr 10, 2000)

*Re: (2kjettaguy)*

I haven't shown them to schimmel yet (just pulled them out tonight). I have a call into him and will try and bring these by his shop tomorrow.
I just took a much much more detailed look at the pistons (all 6) and I can guarantee you there is NO PITTING on the rings whatsoever. This is good.
As for some of the "steam-cleaned" pistons...I don't know. I had some boost spikes while I only had 30# injectors in there so there wasn't much room for error. Maybe 5 boost spikes but I always recognized and got out of it real quick. But probably not before hitting maybe 11psi or so (for a split second).
Just enough - but maybe not enough to do real harm. I'll bring these to schimmel and see what he says. The scuffing worries me but then again, if Bill tells me they look fine I'll be happy and will slap 'em back in.
Thanks.
Later,


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## Stephen Webb (Apr 12, 2001)

*Re: I pulled my pistons...look at these pics and YOU tell me: (nater)*

How many miles on the engine?
The scuffing you see is not a good thing, but is pretty common/normal for higher mileage engines in my experience. The top picture shows scuffing that isn't so bad, but the second picture is cause for some concern -- just from looking at the picture, anyway. I'm no expert, but it wouldn't surprise me at all if detonation can accelerate the scuffing process...
Based on the amount of crud between the top ring and the crown, I'd say the engine has some miles on it, or you are burning a lot of oil. That first picture looks pretty nasty -- from the looks of it, though, there isn't much blowby, so at least the rings appear to be doing their job.
-Steve


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## sdezego (Apr 23, 2004)

*Re: (nater)*

The Scuffing in Pic 2 is not normal. That is caused by too much piston expansion, tolerances too small or a combination there of. It can also be caused by excessive heat, improper break in, improper warm up, improper head torque (cyl wall distortion), etc, etc. When this happens the piston skirts start to stick to the cyl wall a bit and drag the AL off of the piston. After a bit, the rings will smooth-en it out again, but by that time the oil rings are shot and usually the compression rings get worn badly as well.. This could have (best guess) happened during break in and is finally showing its ugly head.
I have seen piston "partial Seizing" happen during break in and not show signs until 2-4K mi afterward. Sometimes the person will have experienced an odd cough or stall, like it ran out of gas for a second. others would never know because it was under high rpm...
I would be curious to see/know the clearance in the piston/cyl that does not have much galling.
Hope that helps.
Shawn


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## RedDevil (Sep 21, 2001)

*Re: I pulled my pistons...look at these pics and YOU tell me: (Stephen Webb)*

Remember seeing a post few months back, with someone having the same problem. 
Scuffing on the pistons was caused by incorrect gaping of the rings, which removed crosshatching on the cylinder walls.


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## need_a_VR6 (May 19, 1999)

*Re: I pulled my pistons...look at these pics and YOU tell me: (RedDevil)*

How did the rod bearings look? I had a set of pistons out of low mile a 9A motor that looked just like that. Ran low on oil, munched the bearings, and the pistons did the same happy dance into the bores. Oil looked OK, oil pressure was OK?
Other then that, improper size or out of round bore would do it.


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## Vr6Fidelity (Oct 4, 2001)

*Re: I pulled my pistons...look at these pics and YOU tell me: (need_a_VR6)*

Important question:
Are the heavily scuffed pistons the same ones that are clean and golden? Its hard to put the pics together. Those pistons are indeed way too hot. I dont know the details of your motor setup. Although a too hot piston still wont fit in a properly sized bore. 
Are there matching bad spots in the cylinder bores?
How well do your oil squirters work on the golden pistons? are they clogged?


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## Gtibunny20v (May 19, 2005)

*Re: I pulled my pistons...look at these pics and YOU tell me: (Vr6Fidelity)*










See the white marks on the edges of the piston. Those are signs of denotation. Looks like the car is running rich and fuel is burning in the ring area causing that to happen. 
The scuffing is definately not normal on a low milage engine. VR6's do have that problem though, usually with 150k + miles.


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## Evolution Marine (Sep 18, 2003)

*Re: I pulled my pistons...look at these pics and YOU tell me: (nater)*

Nater - Your problem is detonation. When the coke is cleaned off or partially removed from the center of the piston, or any other part of the top of the piston, you have to much timing, not enough fuel, or a combination of the two. The heavy coking of the rings is caused by the ring temper going away and the rings loosing some of their tension, both symptoms being caused from the extreme heat created by the detonation process. The scuffing is basically caused by over heating the piston and it partially sticking in the cylinder bore and transferring aluminum onto the cylinder bore surface. This transfer will also affect the piston ring seal and allow oil past the rings, also contributing to the heavy coking around the rings. 

It is not humanly possible to catch this scenario before it does damage. At 5500 RPMs the motor is firing 45 times a sec. out of tune and damaging itself each time it fires. Also. when it comes to tuning, a motor will loose more HP quicker going towards the lean side from optimum A/F mixture than going towards the rich side of optimum A/F mixture. So always richen up the motor 5% more than optimum A/F mixture for durability and very little lose of HP.
Also, I would run, maybe, 2% to 3% more fuel in the front cylinders than the rear cylinders because the front cylinders look like they are detonating more than the rear cylinders, which indicates the front cylinders need more fuel than the rear cylinders.
Detonation puts extreme pressure on the pistons and rattles them back and forth very violently in the cylinder bores when the pistons are very hot, and this combination of events can cause the piston skirts to collapse. So you should measure the piston diameter at the bottom of the skirts against a new piston and determine the difference if any. If the skirts have collapsed more than 2 to 3 thousands it would be advisable to replace the pistons that have collapsed. If this is not done the piston will rock in the cylinder bore to much and will not give the rings a stabile platform from which to do their sealing function from.
Sorry to see the damage to your 3.0L. I know you have a lot of work in it and it is not easy to look at the pictures of the damage to such a nice motor.







- Bob


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## nater (Apr 10, 2000)

Quick update (and posted pics later today when I get home from work)...
Saw Schimmel yesterday and showed him the pistons.
I also showed him the pics I took via email and he (as you guys are) was very concerned.
Once he saw them, cleaned them well, inspected them, etc...he said that they looked very good considering what had happened...
What happened was simply put as me running excessively rich (which I have been at idle for some time)...all of that isht on top of the piston and on the side was unburnt fuel.
Unburnt fuel "washed away" the oil on the cylinder walls which created a lack of lubrication which caused some loss of crosshatch.
No signs of detonation AT ALL. Rings were perfect, pistons perfect (slight scuffing not as bad as the pics made it out to be), and bearings are in such good shape that they could be interchanged with no negative affect.
The "burnt clean" or "steam-cleaned" appearance at the top of some of my pistons (I think two pics showed that) he said looked like that in the pic but in essence they weren't (must have been a flash/camera thing).
He lent me a flex hone, assembly lube, some tips, etc...and said to throw the pistons back in and everything would be fine.
He showed me quite a few other pistons with fairly low mileage (stock and forged) with similar scuffing.
Now is it completely normal? He said of course not, but nothing that would cause problems. All caused by nothing else but running excessively rich (and running rich at idle could easily cause that he said).
One thing some of you may know if you've followed my other posts at one time or another is that I had MAF sensor problems (both with sensor and with faulty wiring) along with a boost leak here or there.
That, along with the notion (in my mind) that running rich never really caused any problems but smoke out the back and cat converter problems (but I don't care about that







) I never rushed out to fix this stuff.
For an unknown reason I have been running rich at idle so I'll have to look into that more. but I've never been rich enough (consistently) at WOT or in high rpm areas.
Anyway, he cleaned them well but gave them back to me after I offered to finish the cleaning process...
Boy do I feel better now.
I did find out that my 3rd gear synchro failed as well as the 3/4 selector so I need that replaced and he is "looking into the head" further.
So the oil may be an issue to be discussed when he's done looking more into that.
Pics of pistons will be posted later today (and hopefully better pics).
Later,


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## nater (Apr 10, 2000)

*Re: I pulled my pistons...look at these pics and YOU tell me: (Evolution Marine)*


_Quote, originally posted by *Evolution Marine* »_ Also, I would run, maybe, 2% to 3% more fuel in the front cylinders than the rear cylinders because the front cylinders look like they are detonating more than the rear cylinders, which indicates the front cylinders need more fuel than the rear cylinders.

Hey Bob,
Thanks for the notes (and everybody else too







)...
In regards to the front 3 vs rear 3...
Per what schimmel has mentioned to me in the past, the rear cylinders always burn hotter than the front (ask him, hopefully he chimes in here as I sent a link to him via email)...
With this in mind, I was very concerned and surprised when the most "damaged" seemed to occur in the front (i expected the rear).
But since the problem was an extremely RICH condition there was MORE unburnt fuel in the front three when it was running cooler. THe rear three were running hotter and therefore burning more fuel, so LESS damage (fuel washing away oil on the cylinder walls and losing cross-hatch).
So, in essence the leaner conditions in the rear were actually a good thing.
According to Bill, there was no signs of detonation or anything like that and that I just need to look into the rich condition a bit more (which I will do).
Looks like I may need a fine tune or may have some other type of problem at idle.
Later,


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## LSinLV (Nov 25, 2001)

*Re: I pulled my pistons...look at these pics and YOU tell me: (nater)*

http://****************.com/smile/emthup.gif Glad to hear it's not fatal!


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## vr6ofpain (Feb 5, 2004)

*Re: I pulled my pistons...look at these pics and YOU tell me: (lsinlv)*

(my car stock VR6, V1 blower, 30# injectors, C2 stage I software)
What should the tops of my pistons look like, ideally? I looked into a couple spark plug holes with a flashlight the last time i changed my plugs and the piston tops were quite black...is that normal/good?
oh ya, car has 83K miles on it, and about 35K have been with the SC.


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## AllCityDubs (Jan 5, 2004)

yes your piston are supposed to be black... http://****************.com/smile/emthup.gif


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## liquidtension (Mar 25, 2004)

im glad it worked out for you


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## nater (Apr 10, 2000)

*Re: (liquidtension)*

Thanks everybody for the input. I feel pretty good about the fact that my pistons are probably just fine.
I cleaned them up some more and threw them back into the car.
















Much cleaner than last time.
And may I add that they were EASY to put in and I don't think it's that easy to break a ring unless you really force things.
I didn't even need a tool besides my two hands.
As long as you dn't force anything and carefully compress the rings with your hands they go in easy. Just wanted to throw that out there b/c I was so worried about how they were going to go in (used the search too much







).
Thanks again!!! Now on to the head and tranny (which I'm awaiting).
EDIT: Ps, I know I have to clean up the surface where the head meets







. 
Any special tool for that???
Later,


_Modified by nater at 11:21 AM 7-10-2005_


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## gvr6t (Jul 31, 2004)

*Re: (nater)*

bah issue with mister B.S. funny how those two letters fit him


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## AlwaysInBoost (Sep 4, 2001)

*Re: (nater)*

Nate did you make sure you put the gaps in the rings 120* apart? 
Give us your compression test results when your finished.
Nice job BTW. http://****************.com/smile/emthup.gif


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## nater (Apr 10, 2000)

*Re: (AlwaysInBoost)*


_Quote, originally posted by *AlwaysInBoost* »_Nate did you make sure you put the gaps in the rings 120* apart? 
Give us your compression test results when your finished.
Nice job BTW. http://****************.com/smile/emthup.gif 

Yea, I put the rings exactly as far apart as it shows in the bentley. 
Thanks man!








Later,


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## mikebobelak (Apr 9, 2002)

*Re: (nater)*

So ,I guess I should unbox the ring compresser?


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## Vdubin474 (Jun 2, 2003)

*Re: (mikebobelak)*

The scuffing may be from not letting ur motor warm up enough before u rip it. Forged pistons will swell faster then the cylinder walls causeing the scuffing if not warmed up properly. Do u here a bit of knocking when u first start the motor? If so thats just ur pistons slappin cause they haven't warmed up and expanded yet. 
Ur deffinetly detonating also by looking at the top of those pistons. How long were those spark plugs in? Sorry this had to happen to ya thats some hard ass work down the tubes. Good luck with everything!!


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## mrkrad (Nov 9, 2000)

*Re: (Vdubin474)*

too rich?


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## nater (Apr 10, 2000)

*Re: (mikebobelak)*


_Quote, originally posted by *mikebobelak* »_So ,I guess I should unbox the ring compresser?









Yea, for sure man!!!








Thanks...
I figured it was safe because I don't think you have my address?? Or do you?








Keep it.
Later,


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## nater (Apr 10, 2000)

*Re: (mrkrad)*


_Quote, originally posted by *mrkrad* »_too rich?


Well, with due respect this thread was titled about my pistons. But just so you know, as I mentioned a bit earlier Schimmel still has my head and is disassembling to take a look.
So, as far as my piston "problem" it was running rich. There is another problem which I have posted before (and maybe even on this thread at some point) where oil was sitting on top of the pistons. That is a seperate 'problem'.
As for vdubin474...there was no detonation. The earlier pics of the pistons make it look like that but there isn't a bit of detonation. 
Oh, and no I've NEVER ripped it before the oil hits 180* (on occasion I've ripped it but barely and that was at 160*)...
Never before they have hit "temp".
Later,


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## mikebobelak (Apr 9, 2002)

*Re: (nater)*


_Quote, originally posted by *nater* »_
Yea, for sure man!!!








Thanks...
I figured it was safe because I don't think you have my address?? Or do you?








Keep it.
Later,

It was all ready to go ,address and all,but I'm lazy,and kids soak up all my time before work. No biggy, . Mikey B.


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## larsonscorrado (Nov 20, 2003)

just to let you know i pulled apart my corrados vr it had 220000 miles on it still ran great no problems with it but i pulled to to put in a built turbo motor. when i pulled it (the motor was only running with intake exhust and a chip) i took it apart and found the same scoreing and 3 broken rings but only the top ring on 3 different pistons i never had any problem with the motor no smoking or los of power. in my opinion i think it is normal for a vr6 to do this as normal as the rings wearing on the cylender wall i just think that is they way they were designed


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## edot (Dec 27, 2004)

looks like to much fuel good luck


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## SoFarKingFast (Jul 9, 2003)

Did you ever get that turbo looked at?
Ryan


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## Reqiuem (Jul 8, 2005)

*Re: I pulled my pistons...look at these pics and YOU tell me: (nater)*

looks like you have a problem in your hands


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## nater (Apr 10, 2000)

*Re: (SoFarKingFast)*


_Quote, originally posted by *SoFarKingFast* »_Did you ever get that turbo looked at?
Ryan

I looked at it... I mean, no oil or signs of it on either the compressor or turbine side.
Just the normal stuff.
Nothing felt "outta wack" either. 
I'm not really worried about that to be honest...I'm still awaiting Schimmel to let me know what he found out about the head. Coming soon.
Later,


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## nater (Apr 10, 2000)

*Re: I pulled my pistons...look at these pics and YOU tell me: (Reqiuem)*


_Quote, originally posted by *Reqiuem* »_looks like you have a problem in your hands









What's the problem? I mean, besides me not having the boost turned up to 19psi and turning out about 375 whp on c2 tuning







.
Oh, anybody know if it's normal that 5 out of my 6 plugs are missing their tips? It almost looks like they all melted?









Later,


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## 2kjettaguy (Dec 24, 2000)

*Re: I pulled my pistons...look at these pics and YOU tell me: (nater)*

Show some marco shots of the plugs Nate...
melted electrodes = detonation and pre-ignition. I smoked a set once







Twice actually. I was a total noob at one point


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## nater (Apr 10, 2000)

*Re: I pulled my pistons...look at these pics and YOU tell me: (2kjettaguy)*


_Quote, originally posted by *2kjettaguy* »_Show some marco shots of the plugs Nate...
melted electrodes = detonation and pre-ignition. I smoked a set once







Twice actually. I was a total noob at one point









Evan,
That was a total joke...







. I actually think you helped me when I first pulled the head off of my stock unbuilt motor back late last year when I plug may have melted and fallen into the cylinder...I'll find that thread if anybody actually thinks that statement was real







.
But yes, I know for sure that if I had 5 out of 6 plugs that were melted that it wouldn't be good...and of course, my pistons wouldn't have looked as good as they do.
Just inserting some humor into this thread b/c I was in a good mood.
Later,


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## 2kjettaguy (Dec 24, 2000)

*Re: I pulled my pistons...look at these pics and YOU tell me: (nater)*

lol good one








Melted plugs rule


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## nater (Apr 10, 2000)

*Re: I pulled my pistons...look at these pics and YOU tell me: (2kjettaguy)*


_Quote, originally posted by *2kjettaguy* »_lol good one








Melted plugs rule

Hey,
Did we see you in the c2 booth this weekend, Evan?


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## edot (Dec 27, 2004)

maybe its time to switch to a standalone.


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## nater (Apr 10, 2000)

*Re: (edot)*


_Quote, originally posted by *edot* »_maybe its time to switch to a standalone.

What?
I don't know what your knowledge is of the situation but I think I'm fine the way I am.







Why standalone?
My a/f is perfect...and I'll say this again, the rich conditions I have had were due to bad maf sensor and then bad maf sensor wiring. 
I've had multiple threads in regards to this...and also it's been mentioned here.
Later,


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## 2kjettaguy (Dec 24, 2000)

*Re: I pulled my pistons...look at these pics and YOU tell me: (nater)*


_Quote, originally posted by *nater* »_
Hey,
Did we see you in the c2 booth this weekend, Evan? 


You may have... I was hanging out waiting to talk to Chris, but he was too busy selling stuff







No worries, I'd rather let him sell stuff than shoot the crap with me. We're you at the booth?


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## nater (Apr 10, 2000)

*Re: I pulled my pistons...look at these pics and YOU tell me: (2kjettaguy)*


_Quote, originally posted by *2kjettaguy* »_
You may have... I was hanging out waiting to talk to Chris, but he was too busy selling stuff







No worries, I'd rather let him sell stuff than shoot the crap with me. We're you at the booth? 

Yea, in the back right by the quick flow manifolds where the oem hids were...
my 'other' screenname is '[email protected]'...Heading up their new lighting division...good things to come







.
So, you probably saw me and v.v.
Later,


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## edot (Dec 27, 2004)

i didn't notice that, i was just speaking from my experiences.


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## nater (Apr 10, 2000)

*Re: I pulled my pistons...look at these pics and YOU tell me: (nater)*

UPDATE:
Car is running fine. 
Just put my first 100 miles on it today. 
Smooth.
Just thought I'd put a true close to this thread.
Feels good to have that thing put back together again. Whew!








Later,


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## VR6rocks (Jun 5, 2004)

*Re: I pulled my pistons...look at these pics and YOU tell me: (nater)*

good job nater http://****************.com/smile/emthup.gif and congrats on the baby


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## tekstepvr6 (Aug 15, 2001)

*Re: I pulled my pistons...look at these pics and YOU tell me: (nater)*

Nice to hear Nate. http://****************.com/smile/emthup.gif


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## nater (Apr 10, 2000)

Thanks guys!


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## zarman (Apr 7, 2000)

*Re: (nater)*

Hey Nate, did you just rehoned the cylinder(s) which lost the cross hatching and used the same rings or did you use new rings?
I also have a built 3.1 and I think maybe I may have the same problem as you. It is running rich at idle. Has been for awhile. Recently the #6 cylinder is fouling up brand a new plug within 1 hour of driving. The plug is completely black and it will cause misfiring. Once a new plug is used the same thing will repeat itself. Compression on 1-5 cylinders is perfect at 200, but #6 is at 175 at best. My engine builder is suspecting that the cylinder wall is loosing the cross hatch (due to fuel washing oil away) and the ring is now dragging the oil into the combustion chamber. The threads on the bad plug is oily while the other plugs aren't like this. We haven't opened the motor yet, but i think this is what's happening. Well it doesn't sound too bad. Just rehone and reinstall eh. 


_Modified by zarman at 10:00 AM 9-30-2005_


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## MarcoVR6SC (May 3, 2003)

*Re: (zarman)*

Could also be a exhaust valve (carbon buildup)) that is leaking. Do a leakdown test and you'll know.


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