Head stud poll

nostatic · nostatic's Garage

All this talk about head studs (looking at previous threads) makes me think we need data. Post away...if you had your broken head studs fixed, if you could say how much it cost to fix (and indicate if you had any other work done at the same time that affects the amount) that would be great.

This is mostly an SC poll, but if Carrera owners have experienced a broken stud, post away.

Jim T · 07-22-2002, 10:11 AM

I checked all of mine when I adjusted the valves on my '78 SC a couple of months ago. All OK (never been changed).

osidak · 07-22-2002, 10:40 AM

I had 7 broken studs. Cost to repair was ~$2200. This included fly cutting the heads as they got pretty beat up. Also replaced some seals and sensors.

ChrisBennet · ChrisBennet's Garage

I've seen/fixed broken head studs on an '86 Carrera (1 stud) and an '81 SC (2 studs). A friend had a broken head stud on his '79 SC. These are all New England cars if that helps.
-Chris

widebody911 · widebody911's Garage

I had 2 broken studs on my 3.6L, ended up rebuilding the whole damn engine. I replaced the stock studs and rod bolts with RaceWare. I even used their $pecial washer$ and nut$.

Jadams1 · Jadams1's Garage

I found two broken lower studs (one on #1, the other on #6) and repaired it right away. Replaced all 12 lower dilivar studs with steel ones and reassembled the engine with new gaskets. Cost to repair was around $300.

ChrisBennet · ChrisBennet's Garage

To loosen the Loctite on the old studs you heat them up quite hot. What effect does this have on the very nearby through-bolt O-rings?
-Chris

Jim Savage · 07-22-2002, 01:08 PM

I found a 2.7 with one broken stud. Wants $500 for it torn down. Is this a good deal?

I have a 76 roller for it. I have an upgraded 2.4 to go in it but thought I should put in a period correct engine instead. What do you guys think????

Jim

rstoll · 07-22-2002, 02:05 PM

No broken studs on my 140,000 mile 83 SC. Yet!

Doug Zielke · 07-22-2002, 03:10 PM

Quote:

Originally posted by rstoll
No broken studs on my 140,000 mile 83 SC. Yet!

And continued good luck to you, Robert!
I was feeling pretty smug with all of my 24 head studs in one piece, then S-N-A-P!
Not that you can hear it happen, but when it does occur it's like flicking on a light-switch...there is no warning.
(Oh yeah.....Carrera 3.2's are *not* immune from this problem either.)

Drago · Drago's Garage

Quote:

Originally posted by Doug Zielke

(Oh yeah.....Carrera 3.2's are *not* immune from this problem either.)

Count me as still smug at 174K and counting

speeder · 07-22-2002, 05:49 PM

John, So were you able to get the old ones out yourself? Heat 'em up and turn? I assume that you did not do/need any other machine work. I'm wondering about this since I have a broken one on what seems to be an otherwise excellent motor. I think that some guys pull the heads for stud-fix job and wind up rebuilding whole thing whether it really needs it or not. How is it now? No leaks? TIA.

86Carrera · 07-22-2002, 08:14 PM

I have a question... what causes broken head studs and other than checking how can you tell if you might have one (e.g sound, lack of performance)?

Pete
86 Coupe

07-22-2002, 09:16 PM

only one, cyl 6, everything is tight and watching it closely. would have done a complete rebuild but needed trany and a few other things first, but now I have the 3.6 idea planted in my brain and it won't go away...

Wayne 962 · Wayne 962's Garage

I've never seen a broken stud on a 2.7 - only pulled studs, which are a much bigger problem...

-Wayne

Jadams1 · Jadams1's Garage

Speeder,

Yes, I pulled out the old studs myself. John Walker posted a pic of where tho heat the case with an oxygen/acetylene torch. I had an assistant apply constant force with vise-grips while I heated. After about 1 minute of heating, the locktite melts and the stud will begin to turn. I did not have any machining done (re-used rings too). I agree that some of the engines out there get a top end or total rebuild just because of the "while I'm in there" syndrome. I opted not to do any rebuilding based on how everything looked, valve seats, seals, rings, cylinders, etc. When a rebuild is required, I'll do a total rebuid. If you are going to pay to have the studs repaired, you may want to do a rebuild. There is a lot of labor involved to replace the studs. The engine is almost torn all the way down.

The engine runs great, doesn't smoke or leak and I have peace of mind that I'm not driving around with broken head studs and beating up my heads.

ChrisBennet · ChrisBennet's Garage

Quote:

Originally posted by sammyg2
Just over 100,000 miles on my SC with no broken studs as of last month.
Question: What symptoms indicate a broken stud? If one were to suddenly break how would you know? I imagine a noise similar ro an exhaust leak, is that close?

They can fail silently. A friend had a PPI done and they didn't pull the valve covers. Compression and sounds were all good but it turned out to have a broken head stud.
-Chris

Doug Zielke · 07-23-2002, 07:36 AM

Quote:

Originally posted by 86Carrera
I have a question... what causes broken head studs and other than checking how can you tell if you might have one (e.g sound, lack of performance)?

Pete
86 Coupe

A very good question, Pete, and one I can now answer with some authority. Here's the (long) story......

Our PCA club has a monthly breakfast run (hi, Bob), and it can be fairly spirited to say the least. During the run, the car performed flawlessly. After the drive, I parked the car and went into the cafe for breakfast with all the other guys. An hour later I started the car and drove off for a few errands. It was then, I noticed something different about the car......

Not a *feel*, as all the power was still there, but rather a *noise* that I would have sworn was pinging....just like detonation from bad gasoline.

I spent the next few days re-filling the tank with fresh fuel, dosing the fuel with Techron, checking the ignition timing, looking for vacuum leaks, all the while convincing myself the noise was due to detonation.

The noise never went away with all my fiddling, *except* when I *retarded* the timing at least 5 degrees. This made me *sure* I had an ignition/distributor problem, so I took the distributor apart and cleaned it. That didn't solve the problem.

I was frustrated, so took the car to my favorite wrench.
He took just one little trip up and down the alley behind the shop, and proclaimed: Head stud...lower right side!

I protested, saying it was not a "clapping" sound, but a "pinging" sound. He said the clapping sound is what you may hear when you have more than one broken stud per cylinder, or if the heads are really loose and beat-up.

And why, I asked him, did retarding the timing stop the noise (just like you'd stop detonation with a timing adjustment)?
He said, all I was doing was reducing the pressure of combustion in the cylinders, especially the weak cylinder.

No longer so sure of my personal diagnostic skills, I went home and pulled the lower right valve cover. The #6 stud fell out on the floor....snapped neatly in the middle.

Moral of the story:
No warning, no real loss of power, nothing much of anything, just a little tinkling from the engine room.
Keep your stereo off now and then, and listen to your motor. It may be trying to tell you something.

911pcars · 07-23-2002, 10:19 AM

Are all Dilavar studs equal? B. Anderson cites 3 different versions of Dilavar studs used throughout the years (up to the last 911 anyway).

It'd be interesting to know the frequency of failure for each type

Silver
Gold
Black epoxy coated

During my rebuild, I installed the black ones (upgraded to 2.7). Knock on wood.

Sherwood Lee
http://members.rennlist.org.911pcars