Broken Cylinder Head Stud in 1987 3.2L 911 Carrera

[911T1972]

Thank you

[86Carrera]

That happened to me at 147k. Not sure about what you should do at 60k but at higher mileage it's best to replace all the head studs and do a valve job. I did rings too but had high oil consumption after that and am doing the pistons and cylinders now.

Your pistons, cylinders and rings should be fine. Since the 3.2s are known for valve guide wear I would do those now. Even with the low mileage I would replace all the head studs because if one of your old ones broke another might soon. The newer studs last longer.

It's funny on the head studs, they can break even on the best kept cars. Seems like their breaking or not is as dependent on time as it is mileage. I was not too happy when I broke mine and prior to that I would brag about my car's durability and low maintenance costs. If the value of the 3.2s hadn't gone up so much recently I would be pretty POed.

These kinds of costs to keep the cars in top shape are one of the major factors driving up values.

[Jcslocum]

With all the work required to replace a head stud, you will quickly see that replacing all of the lower Dilivar studs with regular steel. Or, make a good upgrade and go for the Supertec studs. Once you have it apart, the heads should be rebuilt as well, This will cure and prevent most of all other issues with the engine for many years to come.

Other things that add to the while you are in there list:

Sensors. All should be replaced while engine is out.
Clutch, while you are in there....at least a new disc.
seals on trans and staft fork upgrade
clutch slave

This list will get very long!!!

[Jesse16]

Since I have an 87 that lived its life in a rust free area (GA and northern FL) but was used reasonably frequently and has 240k miles now I was interested in this topic also. When my oil usage got too high and did the top end, I considered replacing the studs but upon tear-down they looked perfect! As I remember, reading on the topic said that later cars like the 87 are not normally in the same failure category as earlier cars and mine has zero corrosion. I left all my studs alone, knock wood. I think its a big job to go in and change a stud, but the stud cost is minimal compared to all else unless you're DIY. If I broke one, I'd do em all.
Did you break an upper or lower stud. Aren't the dilivar studs on one side only maybe exhaust side ?

[Koizumi]

I recommend you take the high road and install Supertec studs. And replace/upgrade everything else while apart. It won't be cheap but you'll have a nice "new" upgraded car, so to speak.

[kostya.lyt]

I had 2 head studs break on the same cylinder on a 40k mile 930. I replaced all of them with the ARP kit.

[Flat6pac]

Turbo has 24 dilivars.
The Carrera/SC has 12 bottom row dilivars. Street car, stock steel replacement should do without problem. Replace all 12 at once or you'll be back.
You have to pull the cylinder and piston on the broken one to get to the stub.
Do a valve job while apart.
Upgrade your cross pin on the clutch fingers
Bruce

[rattlsnak]

p.s. this will NOT be cheap.. !

[GH85Carrera]

On my 85 3.2 at 140,000 after a 4,000 mile road trip I noticed one head was "wet" looking. I dropped the engine for a closer look and no doubt that head was leaking. In the end one stud had somehow become loose. Not one broken stud. To fix the head it had to be milled. That means the other 5 need it as well so a full head rebuild. "While I was in there" with the cylinders pulled off it seemed like a good idea to open the case and check things out. I was glad I did. One rod bearing had a "hot spot" and the oil pump shaft was very worn.

"While I was in there" might as well clean it up and boat tail the case and go with new ARP rod bolts and ARP case bolts. A few other "While I was in theres" and everything was finished up and back in the car.

In the end I was glad I spent the time and money to do a full rebuild. I will roll 160,000 miles this summer.

[gerry100]

Had to have mine done on my '86 3.2 at 106,000.

Agree with other recommnedations, although at 60k it may be overkill.

[Bob Kontak]

Originally Posted by Flat6pac

Turbo has 24 dilivars.
The Carrera/SC has 12 bottom row dilivars. Street car, stock steel replacement should do without problem. Replace all 12 at once or you'll be back.
You have to pull the cylinder and piston on the broken one to get to the stub.
Do a valve job while apart.
Upgrade your cross pin on the clutch fingers
Bruce

You do not have to pull the piston. I am not sure why Bruce is saying this. I think he is pretty busy, which is a good thing.

You can pull the cam and extract the entire set of three heads coupled to the cam tower if you don't want to do any thing else except change lower studs.

Boat tailing the mains is a full rebuild. You need to eyebrow the pistons as well to gain full benefit of minimizing wind related restriction. For a 6,500 rpm street car? I say don't bother.

[Flat6pac]

I say you have to pull the cylinder to replace the broken stud because on a 3.0/3,2 the stud runs through the cylinder. A broken stud, you remove the cylinder, then extract the broken stud.
If the stud is broken flush or sub level, the engine has to be taken apart and a machinist needs to work on the broken stud as there will be grinding everywhere and you need a flat table.
Bruce

[Bob Kontak]

Originally Posted by Flat6pac

If the stud is broken flush or sub level, the engine has to be taken apart and a machinist needs to work on the broken stud as there will be grinding everywhere and you need a flat table.

Got it.

I don't know the stats on Dilivar studs as to where they break. I know that a weak point is in the center shaft due to corrosion pitting. They shear axially from heat cycling at the weak spot. A pit and then the pit turns into a tear across the diameter. Often plenty of meat to get your twist on.

Flush or sub level? Just hang me. A whole different ball game.

[neilschelly]

I'm going to be doing this work to my '88 soon in a week or two. I found a broken head stud (exhaust side also) a few weeks ago doing a valve adjustment. As for while-you're-in-there items, I am planning so far on oil thermostat/switch/seals stuff and the oil return tubes. I'm crossing my fingers that my heads are in good shape, but somewhat bracing for valve guides that need more love.

I'd love to hear what else you come up with for while-you're-in-there items, or how your own repairs go.
-N