So this is what they mean by a head stud problem?

[expernet]

Surprise , surprise, look what I found (or didn't find) when i broke down my 3.0 project engine. The guy i bought it from said it was runnng a little rough when he parked it in '89. Right bank 3 gone, Left bank ALL GONE! Question is what to do next? Any comments /help appreciated.

[Weissach911]

Looks like a classic failure.

If I PayPal you the postage can you send me a broken stud so we can have a detailed look at the fracture surfaces.

I have access to a Scanning Electron Mircroscope and it would be good to try to gain some better data.

[tom1394racing]

You will need to replace ALL the lower studs with steel.

[Flat6pac]

I hope there is plenty of end to get them all out with..machine shop doesnt like that work.
Bruce

[berni29]

Hi

Wow, that is brutal. I really hope that the remains come out without too much of a fight. You would want to change the top studs after such an event surely? They must have taken an extra beating when the bottom ones let go?

Berni

[expernet]

Thanks for your comments , I don't think the PO had a clue what was going on, the engine could not have had any power. The tops of the cylinders and and head mating surfaces are pretty beaten up, the first head gasket I attempted to remove is coming out in pieces. Weissach I will gladly mail you a complete stud once one is extracted. PM your address no paypal needed.

Questions:
What extent of machining should I expect to clean up the mating surfaces?
Are there head gaskets made for flat mating surfaces? The OEM ones seem to fit into a groove.
What kind of damage could have been done to the bottom end?
Cylinder walls seem to be in excellent condition.
only 65k miles on it.

My plan is to hone cylinders, add new rings, get heads rebuilt professionally
add carrera tensioners , a modified street exaust and drive it.

It is an awsome survivor, very original and everything works.

[expernet]

So far so good

I got 8 studs out so far by heating and turning with vice grips, i think the teeth on my vice grips are shot. I am going to get a new pair and work on the last 4. Only 1 has me scare. Only about 1/2 inch to grab onto. I am going to soak this on in PB blaster for a couple of days and then heat and give it a try with new vice grips.




Heads and cam trains are broken down everything labeled and set aside

Spoke to Bob at Anchor Atlantic, Heads will be $750 , having cam bodies and cylinders cleaned. Also replacing all exhaust studs.



Note butcher marks on exhaust ports , not my work! may need to me welded and refaced.

[Brown747]

Check out my thread for a very similar situation I just had.
Broken head stud defeated

Good luck! Thor

[Henry Schmidt]

Before you invest too much time in those cylinders make sure that the sealing surfaces are in good shape.
The CE ring is not designed the seal in combustion so any damage to the inner and outer sealing surfaces will need to be addressed before refitting to your engine.

[boyt911sc]

If I saw your post earlier last month, I could have loaned you my cylinder head stud extractor. The last 2 engine rebuilds I did, took me less than 30 mins. per engine to remove all 12 dilavar head studs. Learned the trick from Tom Butler. PM me if you need some tools for the engine rebuild. Good luck.

Tony

[tom1394racing]

I remove broken head studs by tapping 8 mm threads onto the broken stud end and then using the Snap-on 8 mm collet to remove the stud.

[boyt911sc]

Originally Posted by tom1394racing

I remove broken head studs by tapping 8 mm threads onto the broken stud end and then using the Snap-on 8 mm collet to remove the stud.

Tom,

I was able to removed all the 12 dilavar head studs including the snapped ones without any heat. And this was my second motor in 2011. I'm doing another one this winter. The very first engine rebuild I did in 1998 took me a day to get off the dilavar head studs using heat and all sort of vise grips. After learning your method, removal of these undesirable studs is just a piece of cake. Thanks for sharing your technique. BTW, save me a dozen good cylinder head studs for me. I would need them soon.


Tony

[euro911sc]

Pay attention to Henry's post above. I suspect that the CE ring escaped and damaged the sealing surfaces of both banks making the cyls useless. In theory.

There was a guy on here from some European country that was able to have his machinist grind such a minute amount of material off the top to make them 'usable'. The problem is the plating wraps up the wall and over the top of the sealing surface (I believe, correct me if I am wrong). so you can't just machine the cyl tops and be done with it...

LN Engineering can re-plate for you though. Might be cheaper than finding replacements. If you are replacing pay very close attention to cyl height groups and piston diameter groups.Regardless, you have to measure them and the clearances to be sure they match well.

-Michael

[euro911sc]

BTW, I'd replace ALL the studs... too much to question on the ones that did not break.

[VitoV]

A pipe wrench (aka Stillson) also works well on head studs. Lots more leverage and grip than a pair of vice grips, so you can turn with more precision and have a smaller chance of busting one off at the root...

I like the die-and-collet idea too, but I'm too cheap to buy a Snap-On collet when a Craftsman pipe wrench will do the job.

[911pcars]

You may want to inspect and remachine the 6 cylinder-to-crankcase mounting surfaces (actually 12). Part of the "should dos" on top of the slippery slope.

Sherwood

[dshepp806]

I'd make use of Krol for the penetrant,..that stuff works!

BEST!

Doyle

[wnewbold]

Thanks for pics of your head stud problem. I'm in middle of reseal job on my 1990
911 c4. I am trying to find out if similar problems have occurred on these 3.6L engines. The studs on my motor look like new and engine was running like a top prior to disassembly for oil leak problem.

[porterdog]

Originally Posted by wnewbold

I am trying to find out if similar problems have occurred on these 3.6L engines.

When I pulled apart my then new-to-me '90 C4 to do the first valve adjust I found one popped lower stud, so... yes.

[expernet]

So here is what I learned:

The $19.95 screw /stud extractor from Sears is a must have. Makes the job simple

Some studs must still be heated, I heated on the inside of the cylinder barrel along the base of the stud with a good old bernzomatic.

Since the stud is supposed to match the expansion of the case you have to be quick and make sure you are not heating the stud too. I had my helper put torque on the stud and at the right temp it will give, turn fast or it will lock up again.

I am only replacing the lower studs , Mainly because of the stress to the threads (not because I am cheap even though my kids say I am)

Stay tuned for reassembly!