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After a fun project of replacing a leaking oil housing, we replaced all the exhaust studs (of course). Everything was torqued according to factory spec, with a high quality torque wrench.
While idling in the garage - two of the studs snapped, closest to the firewall. Photos below.
I have snapped a couple of the original studs off. Both were the bottom most studs on an S2, one being the dreaded aft stud of cylinder 2 that can’t really be attacked because of the curvature of the manifold. Ultimately I took the head off, which is a bold task on the S2. But once the head was off I was able to back the broken studs out with careful application of a small pick and a tap hammer. Easy, only took 3 minutes (not counting the 2 hours to get the head off and 2 hours to put it back on, plus the oil and coolant mess. Possibly the worst “time to get at versus the time to fix” repair I have done on an 944. Except maybe replacing the steering shaft on my turbo. That one might be worse… yep, it’s worse.
FYI fellas the allen head intake bolts are the perfect size and length for the exhaust studs. Pull the studs and replace with the German hardware. Butter them up with anti seize and it makes it so much easier when you have to remove the headers never have to fight getting around the studs when removing the headers.
An update - after being told by a machine shop to remove the head to pull a broken stud, a neighbor recommended a metal fab shop to weld a nut on what little of the broken stud was left.
I was skeptical but rented a u-haul trailer to haul the 944 to the shop. 15 minutes later the broken stud was out.
I had the same thing happen to me with the 944online “studs”. I love 944online and their customer service is unmatched. However the kits for the exhaust studs is poor as they are actually low grade set screws, not “studs”. Studs are almost always stronger inYield strength.
Long story short, after the second stud broke I pulled the headers off and am now waiting for the Rennbay billet stainless exhaust studs. These are stainless so I can only assume they won’t be as strong as stock steel studs, but I’m going to give them a try.
I have *never* had a factory stud break or fail on me.
I have had several of the aftermarket stainless/copper nut kits fail even during initial installation. Pure garbage.
V2, yeah just did some more research and with you your input decided to ditch the stainless studs and get the factory studs, straight from the dealer. It is a guarantee that stainless steel will be weaker than the stock studs. Also, at 7$ a piece I think the factory studs are made of a specific material to cope with the heat and thermal expansion. Porsche engineers know their stuff!!!
It is also worth noting that the stainless studs may corrode to the aluminum and make them HARDER to remove than the stock steel studs with antisieze
In this case I don't think its a metallurgy thing - I think the stud kits sold by 944 vendors are just very low quality.
If you came up with your own SS studs/copper nuts from a fastener store you could probably do fine.
Maybe a little bit pricy. And they might not even be good for exhaust hardware as the exact material is not stated. I just felt like posting something.
Just got the Porsche OEM studs and nuts installed. Studs appeared to be a soft steel with zinc plating. Nuts looked to be stainless lock nuts but they could have been inconel? Anyways each stud was 8$ and each nut was 11$ without the discount. In total added up to be about 150$
I’ll keep you all posted how long these last without cracking, hope it’s forever! However I still recommend factory hardware for the exhaust manifold.
03-28-2023, 06:56 PM
Broken Exhaust Studs
