Broken headstuds. Inevitable?
 

Will all 3.0 and 3.2's eventually suffer a dilivar headstud break, or are there tales of high mileage cars, or worn out motors that never had a headstud break?

I've had the lower VC's off my 83K mile '80 SC and, knock on wood, no broken headstuds. I haven't, however, determined if they had maybe been replaced by a PO.

Just curious if the broken headstud plague is just possible, or inevitable.

Nothing is inevitable, other then death and taxes.

I have rebuilt or worked on dozens of motors and have yet to actually see a broken stud. Guess I have been lucky because I have never seen a Dilivar stud on a motor either. I don't think it as common (anymore) as some would have you believe.

Cars coming around for a follow-up rebuild may surprise some people. For a while i'm told the "hot setup" was to install all Dilivars upon improving them. I found just that in my '79 engine during my current rebuild- all Dilivar, none broken. However the engine was weepy in a LOT of places and seems like the head clamping & sealing was poor.

So I have 24 Dilivars (the painted standard type, not the super duper 993 all-thread) that are now going in the scrap metal pile. No way i'm reinstalling those buggers. Plain steel will suit me just fine for my fairly tame 3.2L short stroke race engine.

And metal fatigue. Entropy will get you down every time.

Inevitable, no, likely, yes. And I'd say more likely with the old school dilavars than the steels.

My 81 had the non-coated dilivar studs. The broken stud sheared radially but remained together by a thread. Nut vibrated off as there was no torque remaining. There was some pitting on the shafts and I assume this is what originated the shear point.

Does humidity cause the corrosion? My car spent time in Dallas, Atlanta and Houston before I bought it in 1996. Could the humidity in Houston have accelerated the break vs. a lifelong AZ location which I think has less humidity?

BTW, I had a broken head stud on my SC. If that matters, I think their are a lot of factors that make it hard to determine inevitability.

Thanks,

Chuck

Something to consider when doing a rebuild. Happy thoughts and peace of mind.

Mine went at 100K, unfortunately I think the odds are stacked against you.

My 80SC went 190,000 miles without breaking studs. Then, I replaced the lower 12 with used steel studs for the hell of it. Nothing broke.

my 84 3.2 had a broken steel one at 69K, so I assume they had been replaced at some time. While I had engine out and doing all the "while it's out" I heard a "PING" and another one broke. I replaced all with SUPERTEC, there is more to it than just real strong steel.

Are you sure you did not have Dilivar head studs?
In my 30+ years of working on Porsche I have never, I repeat NEVER seen a broken STEEL cly. head stud. No matter how rusty.
OEM a Dilivar head studs in my opinion will fail sooner or later. With the exception of the lasted fully threaded versions. Haven't seen or herd of them braking.
I'll put rust free used steel head studs in any,air cooled 911 engine, except 2.7's and garrenty not to brake OR pull for life.
2.7 should have Dilivar's, [ preferably the fully threaded ], and case savers! Still no garrenty.

No need for SUPERTEC or any expensiveness, over kill, head studs. Save your money.

Both my SCs had broken studs. More to do with the heat cycling than the miles I suspect.
Alan

Had 3 broken studs on my '84 3.2 engine :(

I'm rebuilt with Supertecs now and I was very pleased :D

I purchased my '80SC with 58k miles, ran fine but had a bad clutch, (good PPI overall). Pulled motor and trans to replace the clutch and fix a few leaks. When I removed the bottom VC's to replace the gaskets, a total of 5 (five) broken studs fell out!
Like they said...no guarantees!

87 with 200K miles, one complete rebuild, no broken studs and did not replace them at the rebuild. They looked great, clean as a whistle. I understand that the breakage is related to corrosion. My car has lived a non-corrosive life. I'm a tightwad and didn't want to spend the $$ at the time, it was a DIY rebuild and had to watch the "while you're in there's".
The definately don't all break, period.

Dick Shift, I stand corrected, the exhaust side were Devilar, but for a $100.00 difference why not go with SUPERTEC with life time warranty. There is no doubt Porsche has had issues with them or they wouldn't have changed them so many times. I put a lot on experince, if you have had no failures on building many engines over 30 years then I say go with what you know.

I ve retorqued heads with the dilivars in place..dont put the valve covers on so you can pick up the pieces in the morning.
Bruce

So you wouldn't retorque dilavars.