Heads off... Now what? Hrmmmm

[neghsmoke]

Soooo here's the story.
I've got a 95 Talon TSI turbo that was purchased a few months ago. Engine would turn over, but not start. Compression was showing about 30-40 PSI on each cylinder, and of course adding oil to the pistons to try and seal the rings didn't help.

I've struggled through removing the head, and finally have it off. Now for the newbie question of the year: now what.

Should I try to remove the Cams and inspect the valves to see if they're bent? Should I take it to a machine shop and see if the head is warped? Should I put it back on and pretend this never happened?

Also, #2 and 3 pistons have some surface rust on the top, and there is some surface rust on the cylinder walls. Is this an extremely bad finding?

Also, if I take it to a machine shop, in what state will they expect to recieve it? Should I try and remove all the valves, cams, rockers, etc, etc or just ship it off in it's current state?

If I should take it to a machine shop, what should I have done to it

 

[Injected]

can you post a few pics of the cylinder head (top and bottom), the pistons etc. There may be something that someone recognizes as a symptom that you are not aware of. Sounds like you have a project on your hands, neghsmoke. Good luck to you.

 

[neghsmoke]

I will definitely do that in a couple hours. Gotta charge up the camera battery

 

[psychlow]

If you've got the head off, usually looking at the bottom of the head will tell you if the valves are bent. If they don't seat flush to the head, they're screwed.

 

[neghsmoke]

These aren't the best pictures ever, but they're the best I can do

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[neghsmoke]

I ran my finger over the valves where they seal, and i could feel a small bump like they're protruding a tiny bit. Visually they look to be sealing, but are they supposed to be PERFECTLY flush?

 

[Prez]

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Thats wrong.

Take it into a machine shop and have them look it over. Pistons show marks from valves hitting them??

Sorry but those pics suck bad...

 

[neghsmoke]

the cam bearings were removed for that photo so the rockers were loose. Not much else I can do except eyeball it and answer questions. The pistons all have four small dents on top, but I assumed it was just part of the casting.

 

[psychlow]

the cam bearings were removed for that photo so the rockers were loose. Not much else I can do except eyeball it and answer questions. The pistons all have four small dents on top, but I assumed it was just part of the casting.

Yeah, the pistons have valve reliefs cast into them.

It's hard to tell from the pics, but it looks like something's going on with the air/fuel. The exhaust valves having those white splotches on them look as if they may be getting burned. It could be just the picture quality, though.

How did the timing look before you disassembled it? Did you check the marks? It could have been that the belt slipped just enough teeth to cause consistent low compression without bending valves.

In hindsight, before tearing down an engine, a leakdown test can be incredibly helpful. You can listen to where the air is escaping, and that tells you where to check for leaks when you open it up.

I'd take it to a qualified mechanic/machine shop and have them look it over.... but that's just me.

 

[neghsmoke]

Other than Head Gasket, Valves, and Piston rings, where else can it be losing compression at? I added oil to the pistons and the compression did not improve at all. The valves look like they're sealing atleast decently. The head gasket however had oil on the top / bottom of it where it's supposed to be sealed. That shouldn't really happen should it?

Just from my observations and logical thinking, it would seem to me that either the head is warped, or the head gasket is bad. Without having too much experience with this subject, it looked like the head gasket was one of those 4 layer metal gaskets that i'm assuming don't do much to help seal a head that is possibly warped?

Maybe i'm just going out on a limb, and someone with more experience can correct me, but after seeing the oil on the top and bottom of the head gasket, seeing oil on the exterior of the engine, and having consistenly low compression in all 4 cylinders, it would seem to me that the head needs to be checked for warp (maybe milled) at the very least, and a new composite head gasket should replace the old one.

am I on the right track?

 

[neghsmoke]

Also, is there a trick to checking the piston rings with the head off? I don't have any compressed air, but i'm sure I could find a way if necesarry to get some.

 

[oldman]

You should have done a leak down before you pull the head, if it wasn't been mentioned already.

 

[neghsmoke]

not much I can do about it now except put the head back on and hope for the best