I've got a passenger side exhaust leak at the manifold. Its very noticeable. What kind of harm would I cause driving it 90 miles, autocrossing the hell out of it, and driving it 90 miles home???

Cold air could leak in and crack the valve/seat. Or you could be lucky.

Or it can leak into the cabin if you run with your top on and windows up......and then kill you.....

it is my understanding the escaping hot gases are not exhaust port friendly.

kevin

Don't use the heater; exhaust gas might blow into the cabin. Otherwise, no panic. Your car will run, but due to reduced back pressure (leak) the engine might not perform as you are used to.

When replacing the heat exchangers, go for SS; it will cost you, but after 5 years mine are still in perfectly good shape.

Drive it like that for long enough, and you will erode away the exhaust port where the leak is.

Is 90 miles + autoXing + 90 miles "long enough"? Don't know. You're risking needing a new cylinder head. How big is that risk to you?

--DD

It turned out that 3 out of the 4 heat exchanger / studs were loose on one side. After tightening it all up, the leak was fixed. Is there a better long term fix? After the leak should I get a new "O" ring? Or just leave it alone..

You might want to consider changing the gaskets.....probably a little toasted from the blow by.

What he said, and if you don't have the stock nuts, try to find some. They don't back off as easily, AFAIK.

What do you do to keep from stripping the bolts? Do you use anything on the re-install?

so the nuts are frozen on the studs, and when you try to tighten the stud turns as well, is that correct? atleast you know you can get the studs out with ease if that's the case. just replace the studs. penetrating fluid, repeat over and over. then do it again. be very patient, just try to wiggle the nuts at first. use as little torque as you can get away with, spray em again. get the correct size copper rings for your exchangers. i attempted to reuse the nuts 1 time. i got new ones at the same time i went out to get a step up stud, didn't need the new stud til i tried to use the old nuts. got a tap at the same time. lucky for me i didn't go too deep when drilling out the old threads. did i mention penetrating fluid?

kevin

The worst problem is snapping the studs off....if they are turning and not tightening, it is likey they are stripped in the head.

Remove them and either get the over sized stepdown studs or helicoil them....replace all studs and nuts, use the copper shouldered nuts and anti sieze.

snaping a stud is the start of the worst part mike. now drilling the remaining stud is when is when it starts to get interesting. buy a hand full of bits save yourself one trip to the store, you can return what you don't use. figure out the deepest you can go. mark all bits with masking tape with that demension. be patient. did i mention penetrating fluid?

kevin