: cylinder head damage



alvarofue
02-10-06, 07:20 PM
The authorized technical service, suposed my car engine was over heated during operation because they found cylinder head contact face (with engine block), wasn't flat enough. They decided to rectificate it some milimeters. Then they explained me that for mounting it was imperative to use a self made liner between the cylinder head contact face and the standard gasket, and they did it so.

After 12 month, the engine had a big leakage of water trough the copper liner. I have three technical doubts about the procedure applied:

1) Is or not usual to find some deformation (not marmol flat) on Cateras engine cylinder heads?
2) Small deformations are able to be absobed by the standard gasket and the normal cylinder head screw tension?
3) Is the use of a liner with same shape of the standard gasket an acceptable solution in case of cylinder head rectification?

alvarofue
02-12-06, 07:18 PM
Any idea?

guardian
02-12-06, 09:19 PM
The Catera has a cast iron block with aluminum alloy heads. It is a dual overhead cam engine, and it is an interference engine.

If my heads were diagnosed as being warped I would want to know why, for certain, first and foremost. What gave rise to the warping and has that problem been addressed, is what I would ask. In your case, if it was overheating, has the possibility of reoccurance been minimized/eliminated? If there is no other evidence or symptom of overheating, then why did the heads warp . . . . if indeed they warped at all.

Also, were it my engine, I would have considered the possibility of improper sequencing and/or procedure when the head bolts were last tightened. Torque wrenches can go out of calibration, head bolts can lose temper and stretch, head bolt threads can be improperly prepared, and more.

In general though, aluminum heads running on a cast iron block are more vulnerable to warping than the older, heavier, cast iron heads. Overheating can cause this. Aluminum has a higher coefficient of expansion than cast iron. Aluminum heads tend to rise up at the center when the overheating becomes too great.

A key question I would pose to you:

Did you have OTHER evidence of the overheating which supposedly happened to cause this trouble with your heads??

If you are saying they shaved the heads and then compensated by increasing head gasket thickness, well, that's machine shop stuff in my view, and I pick my machine shops with great care. (To be honest I do some of my own head and block machining, but NOT all.) When a head is shaved there is a lot of follow up, clean up machining, e.g., chamfering. It is easy to bypass this stuff on a cheap job and doing so can lead to trouble, leaks, down the line.

I have to tell you your whole story sort of worries me some. It's not possible to know, doing this over the internet. But I hope you were in good, competent, hands and being treated fairly.

Was the work done under warranty or did you have to pay? And, again, did you have OTHER evidence of the overheating??

dachew
02-13-06, 03:38 PM
Let me add: Yes, machining the heads and then compensating by rebuilding using a copper gasket of exact thickness is a standard practice. You'll find additional information on that exact question here: http://www.headgasket.com/faq.html#q3

It is very important use precisely the right thickness of gasket. Too little thickness increases the compression and causes detonation which might lead to overheating and other bad things.

There is an excellent article on head gasket failure here: http://www.babcox.com/editorial/us/us80222.htm that I think many will find interesting.

alvarofue
02-13-06, 05:38 PM
Thank you very much both for high lever advises. I never found any evidence explaining the overheating. Engine always has run between normal gauge temperature (never in red), but during hot days around 100 C (+).

I lost confidence on the official technical service (Kovacs Valparaiso-Chile). For the repair I paid more than US$ 3.500 (Including some new spares like water pump, timing belt and tensors, oil intercooler), they extended me a 6 month warranty (now ended), but now, after 1 year, I have to stop the car once again. Probably they are waiting for new profits because of me.

My idea is to do the work by myself, replacing head gaskets and bolts. I will take all your advises in account

guardian
02-13-06, 07:41 PM
Yours is a very difficult situation and there's not much more I can add.

I can tell you what I would do, but that does not make it right or proper; this is just my gut reaction:

I would jettison the shaved heads and go with standard Catera parts throughout. If buying used heads I would check carefully with a surface plate and do much more checking beyond that. I would go with the standard Catera head gasket. I would not buy heads, even if flat, which had been shaved.

I would go over the cooling system very carefully, replace the thermostat (they are cheap), be certain all radiator tubes are fully open, all fans 100% operational, etc. .

Finally, if it were my car I would do the heat exchanger conversion, replacing the factory exchanger with a forward mounted stand alone oil cooler. This would, in effect, add cooling capacity which might help during extreme circumstances. It would also improve the reliability of your car. The Catera factory heat exchangers give trouble sometimes.

You are in a very tough situation and I wish you good luck.

alvarofue
04-29-06, 07:27 PM
I should update this post before, but it is never too late.

Finally the problem with the coolant near the head gasket, wasn't a problem with the Cylinder head job...luckilly
It was that stupid heating valve that always break.
The coolant escaped from this valve and wet the space between the V of the engine. This is the second time this valve has problems.
Is there a final solution for this problem?

The car is now running strong :)