Does the catalytic converter cause head studs to break?

[curlesw]

A Porsche mechanic told me that I should replace the catalytic converter with a test pipe for two reasons: 1) better (i.e. very noticeable) performance and sound and 2) the heat caused by the cat increases the likelihood of causing the head studs on that side of the engine to fail. Is there truth to the second claim? The first claim does not seem consistent with other information I have read. Thanks.

V/r
Wayne C.
83 SC

[Doug Steinel]

I do not think the heads studs "break" because of the heat of the cat. The studs which break are dilavar and this is due to corrosion and the brittleness of dilavar. Head studs might well pull out of a mag case because of heat but not break. That seems more reasonable.

[aigel]

I'm with Doug.

Another thought is: That cat is quite far away from the head studs. I am positive that the temp of the driver's side of the engine (heads, and cylinders) isn't significantly higher than the passenger's side. After all, the engine is oil and air cooled. I'd go find another mechanic.

George

[Jadams1]

Your mechanic is wrong. They fail due to corosion. I 2'nd George, find another mechanic. Mine never had a CAT and I had two broken headstuds.

[ChrisBennet]

I doubt the cat it makes the studs more likely to break. (I've seen more broken head studs on the right side than the left.) I do think that side gets a lot hotter. The cat is really hot. So hot that Porsche puts a shield between it an the tire. It's still hot enough to make the tire rear pressure higher on that side than the non cat side.
It wouldn't surprise me if the valve guides wore out earlier on that side but I've never heard of that happening. I send my heads out so I wouldn't have any evidence one way or the other.
-Chris

[Bill Verburg]

the heat caused by the cat increases the likelihood of causing the head studs on that side of the engine to fail. Is there truth to the second claim?

No, general engine heat, age, corrosion, metalurgy and mechanical stress risers from installation cause head studs to break.

[jdowty3]

Definately replace the cat with a test pipe, but not because of the heat. I thought I had a broken stud for a while but it turned out to be a small exhaust leak from 1 missing bolt on the cat that could only be heard when the engine was hot and under load.

[curlesw]

Thanks for the responses...seemed a bit much for me. There was another instance that occurred which causes me to shed doubt on his truthfulness...think I'll find another mechanic.

V/r
Wayne C.
83 SC

[vash]

Originally posted by curlesw
Thanks for the responses...seemed a bit much for me. There was another instance that occurred which causes me to shed doubt on his truthfulness...think I'll find another mechanic.

V/r
Wayne C.
83 SC

was it that time, he opened the front hood of the car and went, "damn! your motor is gone!"

[aigel]

Wayne:

I do not think that your mechanic is untruthful. He might just not be the sharpest tool in the chest, and having learned from the wrong folks, he may just repeat questionable theories.

Even if he's honest, I'd still not want him to work on my car, of course.

George

[curlesw]

George, thanks, the comment re: the cat is not what concerns me, it's what else happens (which I prefer not to get into). He said he did something, I disagreed because things didn't seem right, he said he would recheck it, he did, said it was correct yet the problem goes away when I get the car back. Given that situation (which is vague, I know) I doubt his honesty. On the cat thing, his comment seemed strange and made in an attempt to impress me with his knowledge, I don’t need that. I already know I know less about these cars than everyone on this board…but I can smell a rat.

Wayne C.
83 SC

[ubiquity0]

I wouldn't expect much of an increase in hp by adding a test pipe either. Unless your cat is clogged up now.

[aigel]

I agree. Why increase emissions on a street car for a few horsepower? These cars run nice and clean.

George