No compression #1 cylinder

apbiii · May 18, 2017

2002 5spd Jetta wagon with 255k mi. Lost power coming up hill and there is no compression in #1 cylinder. I got the car used with 165xx miles and have been running Malone 1.5 with 1019 injectors set up by Drivebywire for about 75k mi.

Had timing belt replaced at 250k.

Car just lost power, no bad noise, was dark so I could not see if smoke. Car runs with no smoke, just major miss. Compression test shows very low, 20psi? or so. Just enough to move the gauge.

I expect bad valve or piston. Anyone have a prediction and a suggested course of action? What am I looking at cost wise? Any help appreciated.

Thanks

Archie

oilhammer · May 18, 2017

Take the head off and look. You may find something along the way, after the valve cover is off.

steve6 · May 18, 2017

Was there any damage to the glow plug when you removed it? If you remove the valve cover is there any evidence of issues from the top? Chances are you dropped a valve and its lodged in the piston, you could be looking at top and bottom end but you'll never know until its further looked into. I have never seen one of these engines just randomly blow a hole in the piston.

Cost.. depends on the issue and if you're having a shop do the work.. $1000-$2500 or more.

Hate to see this so close to a timing belt job.. makes me think there was something not done right. Did you do the timing belt as maintenance or because of an issue?

apbiii · May 18, 2017

The glow plug and the injector look fine. No odd deposits or damage. The timing belt was normal maintenance. I am curious how the timing belt might be involved. I have vagcom but have not checked the timing.

I am a little nervous about running on the off chance something falls apart.

vanbcguy · May 18, 2017

I wouldn't be inclined to run it either.

Even a broken ring or blown head gasket wouldn't put compression to near zero. You're likely looking at something more catastrophic. Best case scenario is a bit of carbon or something hung up in the exhaust valve or something, but that's not all that likely.

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maxmoo · May 18, 2017

I would be suspicious of what may have happened when the belt was changed 5,000 miles ago.

Is it possible the timming was set wrong when the new belt was first installed and one of the valves kissed a piston and then the timming was corrected without checking for damage?

Just playing devils advocate here.....who did the belt....are they experienced on tdi"s?

apbiii · May 18, 2017

Interesting possibility. The shop, who shall remain nameless for now, has a good reputation and has done extensive work for me in the past. They are not a known tdi guru but I have experience with them going back 30 or so years. They have done tdi belts but I don't know how many.

Nothing is easy. Trying to remove the valve cover but there is an allen in the back that won't budge. I hope I can avoid drilling it out. I just anointed it with my favorite penetrating oil (ATF and Acetone) so I'll give it a bit and try it again.

Any suggestions on removing this appreciated.

maxmoo · May 18, 2017

Those little stripped allen bolts on the valve cover often come out very easily if you use a small hammer and a small chisel to make a small notch in the bolt head while tapping the bolt out backwards to loosen it.
I've never had to drill one out yet.

....did I explain that well enough?

BobnOH · May 18, 2017

1/4" drive socket. They're not very tight. Max's method works.

apbiii · May 18, 2017

Thanks I understand the chisel idea. The front allens were to my way of thinking really tight and broke loose with a pretty loud pop. Someone has been in there before me because there is a hex head in the left rear instead of an allen. I will let it sit for a bit and maybe the penetrant will help before I try again.

I was taught not to crank down really tight on valve covers because you just deform the cover and increase the chance for leaks.

turbocharged798 · May 18, 2017

Put compressed air in the glow plug hole and see where it come out. If it really has no compression, it should be obvious where the leak is.

maxmoo · May 18, 2017

apbiii said:
Thanks I understand the chisel idea. The front allens were to my way of thinking really tight and broke loose with a pretty loud pop. Someone has been in there before me because there is a hex head in the left rear instead of an allen. I will let it sit for a bit and maybe the penetrant will help before I try again.

I was taught not to crank down really tight on valve covers because you just deform the cover and increase the chance for leaks.

valve cover bolts should be only 7 ft/lbs

apbiii · May 18, 2017

I have a leakdown tester that I may try to adapt to fit the compression tester fitting. I'll play with that after the valve cover is off.

It is not beyond me to make a fitting that will work with the leakdown tester but probably easier to adapt. It may be as easy as changing the output hose from the compression tester to the leakdown.

For diversion I am fitting the neck on a fiddle at the moment, making progress where I can.

BobnOH · May 18, 2017

I think you'll find some obvious stuff once you open it up.

apbiii · May 18, 2017

I would guess they were more like 25 or 30 ft#. There was no sign of loctite so I'm not sure how they got them that tight without stripping something.

flee · May 19, 2017

Lifters have been known to stick in the bore, hanging the valve a bit open.

apbiii · May 21, 2017

Finally got time and motivation to get the valve cover off. Every thing looks fine to me. I did not turn it over.

Thanks for the tip on the chisel and punch. I needed that on three allens.

I'll get it back to the shop tomorrow and they can pull the head.

whitedog · May 21, 2017

No need for any fancy leak down tools. Just shoot air to it and see where the air comes out. Since it's #1, just roll it over until the locking hole in the injection pump is lined up. This will close both valves. Now shoot air to it and listen.

apbiii · Jun 1, 2017

Verdict is in: Cracked piston in #1

Did something happen to cause this or just bad luck?

Suggested fix is hone cylinders replace pistons and rod bearings.

Could this be related to power increase (Malone 1.5 and 1019 injectors) or timing belt change?

IndigoBlueWagon · Jun 1, 2017

A streaming injector can cause a cracked or melted piston. Check those before reinstalling them.

eddieleephd · Jun 1, 2017

I recommend an impact. A typical dewalt or something, not an auto impact.
This has become a part of my go bag!
They're great for screws and small bolts you don't want to strip.

Genesis · Jun 1, 2017

IndigoBlueWagon said:
A streaming injector can cause a cracked or melted piston. Check those before reinstalling them.

Yep. Do NOT treat this as a random failure. It probably wasn't.

apbiii · Jun 1, 2017

I need to know where to look, I am aware that the injector could cause and will get that tested or use other injectors but not sure what else to look for.

oilhammer · Jun 2, 2017

Pull the engine apart, see what you are dealing with.

I would send those injectors out for proper testing.

apbiii · Jun 2, 2017

Pull the engine apart more than removing the pistons and rods? And what would we be looking for that can't be seen now?

UhOh · Jun 2, 2017

You know, I'm hung up on the fact that the valve cover bolts were horribly over-torqued. Yeah, it's like getting distracted by a squirrel, BUT...

If the shop that did the TB didn't have a cam "lock" tool that doesn't require removing the valve cover then that means that the shop over-torqued the valve cover. If this is the case I'd question EVERYTHING that they did.

I'm a newcomer here compared to most folks. I may have heard of one other instance of a cracked piston. And it might have been from high performance mods. So, just what can crack a piston if not really bad fueling? (seems one should have noticed such poor fueling) It's possible, though not very probable (yes, even the best have bad days), that the injectors were botched.

Timing? Bad rod which caused undue stress on the piston? Bad head gasket (causing a thermal imbalance)? These questions are based on the apparent fact that there was no loud bang which would have indicated the cylinder ingesting a valve.

BobnOH · Jun 2, 2017

apbiii said:
Pull the engine apart more than removing the pistons and rods? And what would we be looking for that can't be seen now?

Valves and appurtenances, off with the head (you may have already done this)

apbiii · Jun 2, 2017

The head is off and apparently the valves are fine.

The shop wants to blame the failure on the Malone 1.5 tune and 1019 injectors and therefore see no need to look further.

The comment on the valve cover is interesting. I had not thought about that. Just how did they lock the cam without taking off the valve cover? I can't say for sure but it seems like it was not removed.

Heading down there now to have a talk and take a couple of pictures.

vanbcguy · Jun 2, 2017

Pistons crack due to heat (or more specifically due to heat cycling). You have larger injectors and a tune. Do you run an EGT gauge?

I would have a very hard time blaming this on the timing belt. If we were talking about bent valves, a torn belt, a bad water pump or any they like that sure.

I assume the car has been starting fine? No CEL? Static timing is pretty hard to mess up on an ALH. Even if it were hideously advanced you'd probably have been aware of that already.

Who installed your nozzles?

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jokila · Jun 2, 2017

UhOh said:
You know, I'm hung up on the fact that the valve cover bolts were horribly over-torqued. Yeah, it's like getting distracted by a squirrel, BUT...

If the shop that did the TB didn't have a cam "lock" tool that doesn't require removing the valve cover then that means that the shop over-torqued the valve cover. If this is the case I'd question EVERYTHING that they did.

I'm a newcomer here compared to most folks. I may have heard of one other instance of a cracked piston. And it might have been from high performance mods. So, just what can crack a piston if not really bad fueling? (seems one should have noticed such poor fueling) It's possible, though not very probable (yes, even the best have bad days), that the injectors were botched.

Timing? Bad rod which caused undue stress on the piston? Bad head gasket (causing a thermal imbalance)? These questions are based on the apparent fact that there was no loud bang which would have indicated the cylinder ingesting a valve.

I've done enough timing belt jobs to see this is often the case, even on the crank pulley bolts. Too tight. Unnecessarily hard later.

No compression #1 cylinder

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