Turbo gaskets

**steveG** · 9th February 2014, 06:48 PM

When I did my Isuzu + turbo conversion 3 years ago I used some sheet copper gaskets (made from some flattened copper water pipe). Thought it was a reasonable idea since I'd used copper crush washers on aircraft exhausts many years ago in a past life. Unfortunately it wasn't

I've just had to replace them as they were leaking after around 45K km's.
I'm using some of Dougal's design T3-T2 adapter plates.
The other issue that I had, was that 4 of the 6 M6 cap screws that hold the 2 adapter plates together sheared off as I tried to undo them. I think this was mainly due to them being too long. When I fitted the new ones I shortened them so they only went about 10mm into the threaded plate.

Here's some photos showing how they failed:
Firstly, a shot of turbo and one adapter plate removed. You can see the leak between the remaining adapter plate and manifold

You can see in this one how the much the gasket has oxidised and flaked into the counterbores on the adapter plate. You can see the sheared M6 bolts too:

Here's one of the adapter plate and gasket that sits against the manifold. This is the one that was leaking and you can see how much the gasket has moved where the scriber is pointing:

Finally, this is the gasket between the two adapter plates. Note the elongated holes where its stretched and moved:

The stainless gaskets that I used between the dump pipe and turbo, and adapter plate to turbo were fine, and showed no signs of wear or damage so I reused them.
Fitted the whole lot back together with VHT Copper gasket cement, including fitting a T3 stainless gasket between the manifold and first adapter plate. Will see how it goes.....

Steve

**Judo** · 10th February 2014, 10:31 AM

How thick was the copper you used as gaskets?

**Judo** · 10th February 2014, 10:43 AM

Just thinking about this some more....EGT's would get relatively close to raw copper melting point of 1000*C. It would go soft and gooey (obviously I'm not a metallurgist) long before that temp I imagine. I think of brazing/soldering copper pipes, and I don't picture a lot of heat going into that pipe before it's malleable. Stainless would need to be much higher and definitely higher than any EGT before it would become malleable.

Edit: Google says stainless melts at roughly 1800*C, but it would depend on the grade.

Obviously I'm conveniently concluding all this after the fact, but I always like it when science agrees.

Thoughts people?

**steveG** · 10th February 2014, 12:03 PM

Originally Posted by Judo

Just thinking about this some more....EGT's would get relatively close to raw copper melting point of 1000*C. It would go soft and gooey (obviously I'm not a metallurgist) long before that temp I imagine. I think of brazing/soldering copper pipes, and I don't picture a lot of heat going into that pipe before it's malleable. Stainless would need to be much higher and definitely higher than any EGT before it would become malleable.

Edit: Google says stainless melts at roughly 1800*C, but it would depend on the grade.

Obviously I'm conveniently concluding all this after the fact, but I always like it when science agrees.

Thoughts people?

Thickness was about 1.6mm. Whatever the thickness of 50mm plumbing tube is...

I agree - copper isn't going to have any strength at EGT temperatures. I'm starting to doubt my memory now, but assuming I recall correctly and it was solid copper gaskets we used to use on aircraft piston engine exhaust headers, the temperature would have been a lot lower being against the aluminium head. Probably only a couple of hundred degC, and definitely less than 550C or whatever aluminium melts at.

In hindsight, it was a less than brilliant idea, but on the positive side - it did last 45K kms - so if anyone gets stuck for a temporary gasket.......

Steve

**Ancient Mariner** · 10th February 2014, 01:19 PM

Very interesting as I have done exactly the same .Used to make copper gaskets for the boys with distorted extractors many years ago with no probs but lower temps involved. As my turbo and manifold are stainless will be interested to see how they go

. If they see 45000k they will probably see me out anyway

If those are all I have to replace in that time I will be pleasantly suprised

Good time to reaply never seize anyway
AM

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