# Riddle me this: broken valve spring



## DankNugz (May 19, 2007)

This is my sisters car. 05 golf with a 2.0 BEV engine code. 125k on the clock.

She broke down on the highway and I sent her over to a friend of mine because I was out of town. Here is what I know.

Low power during her drive home(60 miles), about 10 miles left, check engine light started flashing with a misfire code on cyl 2.

Upon arrival, he checked the obvious, fuel, spark, timing, all in line. He then moved to compression. Timing belt had just been done within 10k miles. 

1: 140 psi
2: 125 psi
3: 175 psi
4: 175 psi

We initally thought the low compression on 1 and 2 were rings, and ordered a head gasket set, ring set, and rod bearing set. 

Once he got the valve cover off, it told us a different story. Cyl 2 intake valve could be unseated by just pressing on it with 1 finger. We double checked timing, and it was perfect. The head also had plenty of oil getting to it (we had quite a puddle when flipping it upside down after removal) so it is not an oil supply issue. 

We then pulled the head, and upon inspection, we realized that the cylinders were in good shape, they still had a little cross hatch left, and there were no marks from valves hitting on piston no 2. 

The head gasket seemed to show a compression leak between cyl 2 and 3 and the head bolts around that area were questionably loose.

The cam looked in good shape, but upon closer inspection, we noticed that the cyl 2 intake lobe had a sharp edge on the top of the ramp. Once the cam was pulled we took a look at the lifters. All of them were fine but cyl 2 intake, which had a dimple on the top side (not as bad as you would find on a car that had slipped time and hit the piston) and had collapsed. The valve was not bent. 

We grabbed a valve, spring, and lifter he had laying around, and installed it in the head after cleaning up the seat and seating surface with rubbing compound. We hit the cam with a wire wheel to clean up the burr on the cyl 2 intake lobe and reinstalled it in the head. We then proceeded to check that the valves were sealing by dripping soapy water into the combustion chambers and blowing air through the intake and exhaust ports. All 4 exhaust valves were sealing fine, but all 4 intake valves had major issues seating (cyl 1 was better than the rest, but they all leaked). At that point we gave up for the night and decided to just order a reman head so we could be done with it. 

We already know what we need to do to fix the problem, but my question is, what could possibly cause a valve spring to break in a motor that is perfectly in time, and why it was only cyl 2 and not all 4?

The reason this is such a mystery is because my friend has been working on these cars for 20+years and has never seen a broken valve spring on any VW, let alone one that is perfectly in time. I have heard the possibility that the engine sucked up water and hydrolocking could have caused the spring to break, but I cannot fathom how that would happen at all or why it would only break number 2 and not the rest of the springs.

Any input is appreciated, I would really like to know what the hell happened here and if it was preventable. :banghead::banghead::banghead:

Sent from my DROID3 using Tapatalk 2


----------



## Anony00GT (Mar 6, 2002)

Could be just a bad spring. It's rare, but it does happen.

Is it a manual? Possible she overrevved it?


----------



## DankNugz (May 19, 2007)

Auto. I have heard that one also. Just like a defective part, it would be rare, but could happen. 

So far I have come up with this:

Over rev

Lack of oil pressure

Hydrolock

Timing failure

Defective Part

As I stated, it had plenty of oil pressure and the timing was perfect. She said she doesn't remember driving through any significant amount of water, and like I said, I cannot see that causing a broken spring anyway. Over rev is possible, but the chance is remote with an auto. That leaves a defective part (valve, spring, lifter, cam, etc.). I would like it to be something more than that, but it seems to be the most likely. Nobody else I have talked to has come up with anything feasible.


----------



## Anony00GT (Mar 6, 2002)

Hydrolock will break/bend valves, not springs. 

Lack of oil pressure will score cams and journals, not break springs. 

Timing failure will cause pistons and valves to smash into each other, not break springs. 

We're left with over rev or defective part. Since its an auto, I'm going with defective part.


----------



## PBWB (Sep 12, 2004)

I've revved my old ABAT jetta (auto trans at 258whp) to 8400rpm with stock valvetrain and never had an issue. I could have been lucky, but just throwing my experience out there.

This is one of those things that happens that just doesn't make much sense. I'm going with a defective part on this one.


----------



## DankNugz (May 19, 2007)

Wow abat with an auto? How long did that last?

I guess ill just have to accept that ill never know what happened and it was probably a defective part. 

On a side note, im putting the broken spring on a string and giving it to my sister for christmas. 

Sent from my DROID3 using Tapatalk 2


----------



## Anony00GT (Mar 6, 2002)

PBWB said:


> I've revved my old ABAT jetta (auto trans at 258whp) to 8400rpm with stock valvetrain and never had an issue.


:what:

Stock OBDII valve springs result in valve float below 7000. If OBDI, it can go a bit higher, but 8400 is a bit much I'd think...


----------



## PBWB (Sep 12, 2004)

DankNugz said:


> Wow abat with an auto? How long did that last?


 I honestly can't remember, it's been like 7 years now. When it was 258whp I was running only 15psi ([email protected]). I ran it like that for a bit and then turned it up to 17psi but it was too much for the torque converter. Pretty soon every time I got into boost it smelled like the trans was on fire. :laugh: My dyno plot is in the ABAT dyno thread under my name. Kept up with a stage 2 b5 s4 though at only 15psi! Here's the dyno where it made 258whp at only 15psi.....




Anony00GT said:


> :what:
> 
> Stock OBDII valve springs result in valve float below 7000. If OBDI, it can go a bit higher, but 8400 is a bit much I'd think...


 I'm pretty sure at that point in time I had switched to an obd1 head that I had ported with a TT266. I think that was the setup at that time. I just remember there not being a rev limiter on the c2 setup back then (before emissions compliant software, or as the new guys know it as the rear o2 delete/emissions delete software).....well there was, but for some reason not on my auto trans.

I've done a whole slew of things you're not "supposed" to do, to include a deramped TB on an obd2 car. I had one on my old turbo jetta, and I still have one on my all motor jetta daily. Mpg's drop a tad, but gobs of torque make up for it. I've pulled mk5's uphill in REVERSE with my all motor jetta.....Like I said, GOBS of torque!


----------



## Anony00GT (Mar 6, 2002)

PBWB said:


> I've done a whole slew of things you're not "supposed" to do


Haven't we all :laugh:




PBWB said:


> to include a deramped TB on an obd2 car. I had one on my old turbo jetta, and I still have one on my all motor jetta daily. Mpg's drop a tad, but gobs of torque make up for it. I've pulled mk5's uphill in REVERSE with my all motor jetta.....Like I said, GOBS of torque!


I hogged the heck out of my OBDII throttle body. It works properly with no faults, although I wouldn't say the result was "gobs" of torque. More like slightly better throttle response. I'm running N/A though, ported head, 276 cam, header, MKIV intake. It's the later DBW throttle bodies that hate being ported, like, at all.


----------



## PBWB (Sep 12, 2004)

Ask travis or anyone thats been around a while....its all obd2 platforms that dont like deramped throttles. And I guess I got the better end of my deal cause I can start in 3rd gear rather easily.....gobs for me.:beer:


----------

