Broken head stud on 1984 Carrera

[MIKE84]

Just bought a 1984 Carrera; love the car( my first porsche). Took the car in for service. (New rear calapers, new pads, new clutch cable, fixed oil leak over right valve cover but when the technician ( Rennwerke, Elmsford ,NY) was doing the valve ajustment I got the phone call. ) One broken head stud.

The car runs great and has 116,00 miles on it but had an engine rebuild at 75,000 miles: Top end, new valves and guides, gasket set, piston/liners, new clutch, cam oil line. (Rebuild done by Auto Sprint in Brewster, NY.). Car still needs new shocks, tires and came with 15" phone dials. I would like to up grade to 16" fuchs.

Tech at Rennwerke said drive the car for the summer and bring it back this winter and he will replace all 12 head studs on bottom for $3,500.

Questions:
- Will I damage the car driving it?
- Can it be properly fixed?
-Is $3,500 a far price?
- Why did this car need a rebuild and why did a stud break?
- Does any one known the best Porsche repair shop in NY?

Thank you for any help or advice any one has , Mike Cola

[porschenut]

I have limited mechanical knowledge, but a rebuild at 75k seems awfully premature for a 3.2. Unless it had significant defects it should have gone twice that.

I also think that for $3,500 you should be able to get a LOT more than just new head studs. That much should almost get another rebuild.

I don't know if it driving it that way will cause further damage, but yes it can be properly fixed. I'm sure you'll get plenty of knowledgeable replies to your other questions.

[masraum]

The car will probably be ok with a broken headstud for the summer.

It does happen to 3.2's as well.

[TonyG]

If your mechanic pulls the thing apart, you replace ALL the studs.

And you do a few more things once you're in there.

The bottom line, is that it's about $3,000 labor to pull everything from the cylinders and up apart on the engine. Given this, you rebuild all the parts "while you're in there" which you can buy for about $1500

Thus for another approximately $1000, you can buy and have installed:

new piston rings
cylinder heads rebuilt & new valve springs
24 new cylinder studs/barrel nuts
new exhaust studs/hardware
new timing chains/guides/tensioners
all new gaskets/seals/O rings


The total bill for all of the above work (including new clutch disk, resurface flywheel, and a few more things) was $4500 to have this done on my '82SC, and the work was done by a very reputable mechanic here in Los Angeles.


I suggest you shop around.

TonyG

[nostatic]

the engine was likely rebuilt due to premature valve guide wear (not uncommon for a 3.2, although it usually shows up in the 40-60K mile range). It is a shame that they didn't do the head studs at that time.

If you do a search you'll find people here who have driven with broken head studs. My hunch from reading is that with one you should be OK for the summer...but it is somewhat of a roll of the dice.

[Early_S_Man]

Mike ... and to Tony, and other misinformed neophytes ...

There is no need to replace all 24 head studs, as the upper rows are steel, and good for at least 1,000,000 miles ... the lower studs are Dilivar, and need to be replaced with the same OEM steel studs as the top row, details of which was either omitted by ignorance, or carelessness from the above post! You don't replace Dilivar studs with Dilivar studs these days ... unless an unscrupulous shop is involved, or incompetence is the Modus Operandi! The knowledge that Dilivar studs are/were a problem has been around for more than ten years, now, thanks to Bruce Anderson and Jerry Woods!

Yes, a 'top-end' job would be prudent, and my recommendation is to get Wayne's rebuild book, do some serious studying, and plan on doing the job yourself ... sending out parts for machine work to quality shops like CE or EBS.

[Doug E]

Definately a roll of the dice but I drove my SC last summer with 3 broken studs (even doing 2 DE track days) and then rebuilt it myself.

I agree that $3,500 is high for just 12 new studs so you should clarify (ie., get in writing) exactly what is included in that price and then shop around.

Check the Engine Rebuild Forum for inspiration if you are remotely considering doing the rebuild yourself.

[kach22i]

Originally posted by MIKE84
.................doing the valve ajustment I got the phone call. ) One broken head stud.

Interesting, this answers one of my long standing unanswered question that of: When doing valves will a shop/can a shop check for broken head studs.

I was wondering if a shop with good intentions but bad luck would check head studs by torqueing them to I believe 26 lbs and accidently snap a few. I suppose not all shops would tell you they messed up, and would dab a little lock-tight on them and give it back to you. Would not take long for the problem to show up, right?

So far, so good with mine, but I can't help feeling the Dilivar's are a time bomb waiting to go off.

[TonyG]

Early_S_Man

MisInformed?

Uhhh no. Not even close.

Your little snippet of info is old news.... It's been discussed on this board and others a zillion times.

But thanks for bringing it up for the zillion and first time....

Anybody that spends the money to pull everything apart, and just replaces the bottom 12, is a fool given the fact that the top 12 studs are almost trivial in cost with respect to the project.

Why risk it? To save $100 bucks on a $4500 rebuild?

Imagine how STUPID one would feel after spending that kind of money, to have a top stud fail...

All the studs are over 20 years old... (20 years of heat cycling)

TonyG

[Early_S_Man]

TonyG,

In spite of your 'attitude' otherwise ... you are still quite, quite misinformed!!!

Where in all of the world, pray tell, have you ever seen a case of an upper row steel 911 stud failing ... except in YOUR IMAGINATION???

John Walker has never seen one in over 30 years of experience with 911 engines ... and has posted that 'tidbit' here ... that you apparently missed in your thorough search!

Your ill-advised recommendation ... is, and was, in your case, a waste of over $100 ... for a worry about a problem that DOES NOT EXIST!!!

YOU haven't seen A ZILLION of anything, ever, in your life, much less posts on Pelican, and your exaggeration bespeaks volumes about you, and your MTV/Simpson's- inspired existence, and tendency to rant, Beavis!!!

ps,

You still haven't stated what kind of studs you had 24 of installed in the SC ... details, details ...

[nostatic]

the only reason I could imagine for swapping out *all* of the studs would be if you wanted to go to a higher compression engine (swapping out P/C). In that case, going to all Racewear would be a good idea, no? Or would the factory steel be OK in that case? Or would it depend on what c/r you ran?

And on a semi-related note, does anyone know of a dry-climate car that has failed studs? Is it in fact corrosion related?

[FenderGuy]

so which is better the SC or Carrera?

[TonyG]

Early_S_Man

My attitude is a direct response to your attitude.

And, I quote my advice on what I've personally seen.. not other people's opinions. Big difference.

The facts are pretty simple... 20 - 25 years of heat cycling is starting to take its toll on these cylinder head studs.

$100 is a small price to pay in the big scheme of things to ensure that there is no problem. The penalty should there be a problem is about $3000 and at least 2-3 months of downtime.


So when you rebuild your engine next time... use 20 year old fastners. I'll be using new ones (and I just did).

TonyG

[TonyG]

nostatic

Yes. I saw a 3.2 engine with broken top and bottom studs here in Los Angeles. (although where the car was located/used could vary considerably... ocean to desert)

TonyG

[ChrisBennet]

Originally posted by kach22i
Interesting, this answers one of my long standing unanswered question that of: When doing valves will a shop/can a shop check for broken head studs.

I was wondering if a shop with good intentions but bad luck would check head studs by torqueing them to I believe 26 lbs and accidently snap a few. I suppose not all shops would tell you they messed up, and would dab a little lock-tight on them and give it back to you. Would not take long for the problem to show up, right?

So far, so good with mine, but I can't help feeling the Dilivar's are a time bomb waiting to go off.

I don't think any shop familiar with 911's is going to retorque head studs on a motor that hasn't been recently rebuilt. They know that "retorquing" an old rusty head stud is a recipe for breaking studs and they will let sleeping dogs lie. If anything, they'll give them a little twist to check that they aren't broken already. Usually the stud with a attached nut is just lying there when you remove the valve cover. (The last one I saw had an extra head stud washer lying with it. What the ???)

I think torquing a dry rusty fastener will yield a quite different bolt stretch value than what you'd get torquing them under rebuilt conditions.

Does anyone even use the simple torque method anymore? I use the later torque+angle any method as specified in the '84-'89 Carrera manual.

Perhaps Henry will weigh in and correct me?

-Chris

[MIKE84]

Thank you for all the help and advice. Mike Cola

[ken_xman]

Mike,
Cheech at Renworks is very good, but pricey. If you have not joined the local NY PCA... you should.....admitidly I still need to also. I work in westchester and know several routes for repairs. There is a guy in Newburgh that is suppose to be very good also. I am having him align and drop my 87 in the fall. I have met several porsche guys in the area, all quality people and PCA members.
Ken

[sammyg2]

I'm with Warren on this one. I'm in the process of replacing only the lower 12 studs with steel studs. I see no logical reason whatsoever to replace the top ones. The only top stud I have ever known of breaking was on a 930 with all 24 dilivar studs.
I have never been one to replace something for no logical reason, must be the mechanical engineer coming out.

My car has one broken lower stud on the #5 cylinder. It has been a California car all it's life, first in the Ventura area and then in north orange county for the past 15 years.

[john walker's workshop]

nope, never seen a top steel stud break. a waste of time and money to replace them with new steel studs.

[kach22i]

I had this filled in my folder on the subject, so it must be good.

Quick fix:
Intermediate stud pulled
remove the stud and tap the hole 10x1.25 about 1" deep. install a short bolt with an aluminum sealing ring and don't worry about it until you eventually rebuild it. the hole takes the tap without further drilling, and there's really no damage done where you can't go back to a 8mm stud/washer/nut.