Duke

Turned out that my extreme exhaust poppings and flames were because cyl. 1 was waterfilled and the fuel for that cyl. went straight out the exhaust!!

It's multi layer steel headgasket from Guru Racing.
I used copper spray gasket during assembly.
The head was done 5000 km ago so it should be straight.

It leaks in cylinder 1 so I guess is it's leaking from the front water passage.

I forgot to put oil on the head bolts before torque down and the 2 allen bolts on the water passage was reused. One of those bolts was in really bad shape but I reused it anyway (don't ask me why).

So what do you think? Is it possible a re-torque can solve this leak? Or should I also lift the head and make the whole procedure once again but with a bit more copper spray?

I spent 34 hours in the garage the last couple of days and now this.... I'm about to break down!
Thanks for any advice

Perry 951

Why not re-torque and find out? It won't cost you anything but part of your Sunday afternoon.

Let us know how it goes.

NZ951

Duke, I feel your pain, seriously. I have been through some late nights with mine in the last few days... there is a pot of gold at the end of the rainbow though. Go have a sit down for 30mins, beer, and then get back into it. I cant give you advice on what to do, others will have better knowledge than me. A re-torque seems like step one though.

Mike S

The first time I used that headgasket I used copper spray and I had a 2 coolant leaks, both of which were external. I just redid my head and did NOT use the spray this time.....no leaks at all. I know Tony G had similar results as well. You may give it a shot without the copper spray. When I pulled mine it was a slimy mess.

AlexE

When were the head studs last changed?

Dave E

Take a day off first!

Laust Pedersen

Attached from a discussion on another list are some torque number relationships with different treatments and surface finishes.
If the numbers are in the ballpark, you will gain significant clamping force by oiling the nuts as prescribed in the manual.
So my vote is for oiling the nuts and re-torque.
I also had a "self-sealing" experience on another car. Oil was seeping out under the head gasket, but after a few months (of heat cycling?) the seepage disappeared.

Laust


Date: Tue, 23 Mar 2004 12:22:47 -0500
Subject: RE: road wheel mounting nut
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I was just routing around in a reference manual, and found an interesting table of the "Effect of Lubrication on Torque". It reminded me of the recent discussion on torquing alloy wheel nuts. I was amazed at the decrease in the torque required when a lubricant is used. The table is as follows:
- No lube, steel 0%
- Plated and cleaned 34% decrease
- SAE 20 oil 38%
- SAE 40 oil 41%
- Plated and SAE 30 45%
- White grease 45%
- Dry moly film 52%
- Graphite and oil 55%

It really makes you think when you tighten bolts - put graphite on and you torque to less than half the specs?!

Chris Pyne '72 INT Mk III 133/5771 Thunder Bay, Canada

PS. I had personal experience recently when I was replacing the water connection on a porcelain toilet tank and put some Vaseline on the threads - I lightly hand tightened it, and the damn thing split right open......but that's another story!

Chris

Duke

Thanks guys!
I'll leave the car in the garage for a week and clear my (own) head by continue to build my kitchen..

Very interesting regarding the decrease in torque with lubricants!

How do I perform the retorque? Just loosen the headbolts in the correct order and then torque then down again?

Eyal 951

i find that copper spray to be crap. But i can't prove it to myself yet, so i stilluse it. I just did today on my intake manifold gaskets.
~Eyal

Peckster

Heads on some makes need to be retorqued as a matter of course. In those cases, you don't back off, you just set the wrench at the required max and follow the pattern once.

Duke

Unfortunatly that cannot be done with the standard procedure since it used degrees in the last 2 steps and not a specfic torque number.

Duke

Here's a broken man besides his broken car...

Tom M'Guinn

The stock studs are so-called stretch-to-yield and are not designed with a re-torque in mind. Re-usable studs like Raceware are designed to be re-torqued after the first heat-cycle, and so those studs come with a specific torque spec.

dand86951

I don't really know if the factory studs are in fact a "torque to yield" design. The original manual instructions for torquing the head studs was a three step process to a torque of 65 ft-lbs. This is taken straight out of the manual. Later in the years Porsche changed to the three step process to an initial torque to 15 ft-lbs and then two 90 degree steps. The head stud itself did not change. My theory is that Porsche decided that the 90 degree method gave a more certain preload of stress in the stud regardless of condition of threads or whether oil was used or not.

As shown above the effects of different lubricants on clamping force derived from a given torque is dramatic. I don't think the 90 degree method results in a high enough stress to stretch the stud to yield. Once a bolt goes to yield it looses a lot of strength and I don't believe Porsche would design a torque spec that would leave the stud in a weakened state.

Duke if you followed the 90 degree method you most likely got the clamping force needed even if you didn't use lubricant.

Peckster

I'd just take them up to 70 then. Worth a try I guess, although I doubt it will work.