Removing broken head studs

[Doug Zielke]

I recall SCWDP Founder, Leland Pate, wrote in his excellent engine rebuild overview, that he **didn't** use an oxy-ace torch to remove the studs. He used only brute strength on the end of a ratchet, if my recollection is correct.

I cannot believe he was able to do this.
And if he did (can't doubt our esteemed Founder...can we??) all I can say is he was $hit-house lucky!
I say this, because I have just extracted my first broken stud.
So far, this has been one of the scariest parts of the 'Bombers top-end job.

Thanks to red loctite, those suckers are in there for keeps!
Only with several minutes of concentrated heating from the oxy-ace torch, did the stud (grudgingly) begin to move.

Forget (Mr. Pates "Method" not withstanding) trying to turn these out without heat. And forget about using propane...the alloy case sucks up heat like a sponge does water. Oxy-Ace is the only way to do this.
If you're going to replace head studs yourself, don't mess around...or you'll be seeing that guy with the EDM machine.

Thanks (yet again) to John Walker for all his advice. Without it, I and many others would have surely f'ed up our head stud jobs.

[island911]

Excellent, Doug -- So you followed John Walkers advice on pulling the studs, eh? I guess we could say you "pulled a John Walker" . . .no doubt successful; but I hear it's not polite.

[Superman]

I tried doing it with propane first. All I can say is "You gotta be kiddin'!" Five minutes of concentrated, sharp propane flame on that case was barely able to warm it up. Seriously, it was not as warm as a cup of coffee. That case sinks heat very well.

I guess that working on 911's exclusively 8+ hours per day for thirty years has taught JW some things. A minute or so of oxy/acetylene heat and those things just turn right out.

After that, I tapped the threads and test-fit them with the new studs. When satisfied, I put a piece of tape around a machinist's ruler at the proper installation height so I could install them all quickly and easily. Installation is not done with tools...you spin them in with your fingers.

The 'Bomber will be reassembled soon, as it sounds like Doug can't keep his hands off her.

[HawgRyder]

Doug:
Does this mean we have a "engine in" bash?
LOL
Seriously...you know I'm available on short notice for assistance (gotta get a life).
Are you installing the new studs with red loctite....or is there something better?
Bob

[Doug Zielke]

FOR SALE:
11 & 1/2 Dilavar head studs. Slightly used, but very useless.
Best offer or will trade for a roll of paper towels.

[dtw]

Stick cotton balls on the ends of them and use them as Pelican-grade q-tips?

Though I would not want to use an oxy torch if one got stuck in my ear...

[HawgRyder]

Doug...you looking for a WHOLE roll of paper towels?
And I thought you were an OK guy...geeez...talk about inflating the price of things...LOL
I see you got them all out....great job...now just have to get new ones in.
Bob

[Doug Zielke]

Originally posted by HawgRyder
I see you got them all out.....now just have to get new ones in.

That will be the e-z part, Bob.
I just finished chasing the threads with a nice, new tap.
Already to go!
Now, where's that tube of red Loctite??

[pkfrdh]

Is this a year specific problem for 911 motors? Did the manufacturer of the bolts allow a quality control issue to cause this problem and is it a cylinder specific or "side of motor" specific problem? Has anyone seen a trend above which cylinder a bolt would tend to break or on a specific side of the motor?

If it is random...could it be that the bolts have a high lemon factor to the quality control?

Anything to do to try to make sure it doesn't happen to a motor as far as driving/rpms or?

Just wondering what's up and if I can minimize the chance of it happening.

Thanks for any input.

JGL

[ChrisBennet]

I just heat the stud itself up. It's getting thrown out anyway. Never had a problem but I've only done 50-60 studs and they were all in aluminum cases.
-Chris

[Superman]

JGL, nobody answered your questions. Porsche used Dilivar studs on the exhaust side of their engines from the mid-seventies all the way into the '90s, I think. These studs did not have a QA problem. They had a thermal expansion rate similar to the aluminum cylinder, so they were considered ideal. Now what we're finding is that they corrode and break after 15-20 years. Just about all 911s made during that time are vulnerable to this.

[RAM]

Should have used A286. It's a high temp alloy that is also corrosion resistant up to about 1300F.

That was my nerd input for the day.

[RAM]

Should have used A286. It's a high temp alloy that is also corrosion resistant up to about 1300F.

That was my nerd input for the day.