Amazing Broken head stud removal story!

jtgith · 12-10-2002, 02:35 PM

On the final few days of a complete resoration/update of my 1984 Targa, I decided to check out an oil leak that just started after my engine rebuild. I had run the engine many hours (not driven because body is not finished being painted) without a drop of oil under the car. Last night it started leaking on the left bank towards the front. I removed the valve covers only to find bad news. The majority of the the leak was from a rocker shaft the had moved out of place. As I removed the valve cover gasket, a broken head stud and nut fell out of the head. It was on the exhaust side of the engine. I had lost one of the head washer during reassembly and used another type of washer in its place. Bad move. The thermal expansion properties must have been enough to break the bolt or finish off a fracture. Either way I dreaded removal and teardown of the engine since I just finished a rebuild.
Before jumping into engine removal, I tried an alternative. I bent the heat shield to expose the stud, heated the case, and use a hammer and punch to slowly turn the stud. It took about three hours, but it worked. I was able to replace the stud without engine removal.
If anyone has the problem let me know and I will lay out step-by-step how I did it.

CarreraS2 · 03:34 PM

Quote:

Originally posted by jtgith
Before jumping into engine removal, I tried an alternative. I bent the heat shield to expose the stud, heated the case, and use a hammer and punch to slowly turn the stud. It took about three hours, but it worked. I was able to replace the stud without engine removal.
If anyone has the problem let me know and I will lay out step-by-step how I did it.

OK, I totally don't understand what you are saying.

I don't see what "heat shield" you could bend that would give you access to a broken off head stud, I guess I am missing something. Do you have a pic?

Doug Zielke · 12-10-2002, 03:09 PM

Well, seeing as there is only about 3/8" of head stud exposed where the cylinder meets the case....that *is* amazing.
If you really did manage to turn the broken stud out with a hammer and punch, you should also go to Vegas this weekend.

yelcab1 · 12-10-2002, 03:49 PM

Replacing the washer with another "run of the mill" washer was a bad move, but I am glad you recovered.

jtgith · 12-10-2002, 04:01 PM

It is a true story. I don't have pics of the removal. It took a bunch of patience and I did not think to stop and get out the camera. If you are able to mark the stud (very difficult due to stud material) you can melt the Loctite with a torch and with a great deal of patience and determination it did unscrew from the case.
This removal would not have worked if A) it would have been a stud on the intake side of the cylinder, B) it would have broken off flush, or C) I didn't have 8 different types of punches to ruin.
Needle nose Vise-Grips played a big role after I reshaped them on the bench grinder.

I have tried Vegas before.....I have better luck with my 911!

Doug Zielke · 12-10-2002, 04:05 PM

jtgith......last year around this time, someone started a thread: "Pelican D-I-Y'er of the Year Award"

You get my vote for the '02 award.

jtgith · 12-10-2002, 04:31 PM

I post to this board to try and help people out. Not to brag. I was just amazed that it could be done. I am a true Porsche fanatic. Since it seems like some people doubt my accomplishment, here are some pics. Enjoy!

beepbeep · 12-10-2002, 04:39 PM

Jeeez...yepp. You get the "DIY-award of the year"

OT:
Now that reminds me when i changed timing belt in ex. girlfriends Volvo 740 w/o removing the fan and w/o using special flywheel-locking tool. (Despite Haynes saying otherwise) I locked the flywheel with clutch and e-brake in 4:th gear and marked all positions with Tip-X.

Sometime, there are some really non-orthodox ways of fixing things.

CarreraS2 · 12-10-2002, 04:39 PM

I certainly didn't doubt your accomplishment - I just couldn't visualize what you were describing.

I now see from the pics, though!

That seems pretty damn cool to me. It took you three hours, but what a huge amount of time and aggravation saved!

Apparently, the studs almost never break on the intake side, so this method may work a lot of the time. You should market a custom set of tools!

bell · bell's Garage

damn.........you get my vote too!!!!
nice work on saving the frustration of a re-drop

beepbeep · 12-10-2002, 04:51 PM

Hmm...darn, that could work pretty often!

How hard is it to band back those aircooling shields? Actually, you could even cut-out a piece of them where studs are as there are no cooling fins there, preventing bending in the first place!

Doug Zielke · 12-10-2002, 05:55 PM

When I removed the Dilavar studs on my motor, I needed a *lot* of concentrated heat from the oxy-ace torch before the Loctite melted, releasing the studs. Removing a stud using the "jtgith Method", might be tough if the studs are really glued in, like mine were. Certainly worth a try, though.

But I'm wondering.....in a complete rebuild of the motor, why wern't *all* the Dilavar studs replaced when it was apart?
From what we have learned about Dilavar studs, it's only a matter of time before another one lets go.

cowtown · 12-10-2002, 06:15 PM

As someone who just recently pulled 24 studs from a completely disassembled engine on a stand, I have to say WOW, you are patient. I was swearing enough with the things completely exposed and using a stud removal tool. I never would have thought to use / had the patience to do what you did. Nice one!

boyt911sc · boyt911sc's Garage

Mr. DIY of the Year Man

I recently replaced the 12 Dilavar studs after many hours of heating the case and a lot of patience to completely finish the job. Stud removal is not that easy!! I initially tried using all sort of tools to make the stud turn after heating (CH inplace) and finally went to the engine teardown.

I am not sure whether it was luck or talent for your success but I do respect your accomplishment. You've achieved something where most of us have given up or failed.

Congratulation!!!!

A Quiet Boom · A Quiet Boom's Garage

Just a thought, many years ago I encountered a car with a rounded oil drain plug that nothing could grip so I welded a bigger nut around the rounded hex hex and removed it that way. Could you possibly have cut the stud with a grinder and welded a small nut on? Anyway good job with the removal, you have more patience than most.

Mike the mechanic · 12-10-2002, 09:26 PM

Dilivar doesn't take well to welding.

Chuck Moreland · 12-10-2002, 10:17 PM

Interesting. Did you have to constantly heat the case throughout the extraction, or just to get it started?

Bobboloo · Bobboloo's Garage

You have my vote for DIY of the Year.

I've heard that you should treat dilivar like rod bolts. That is they shouldn't be re-torqued. If these were re-torqued and not new dilivar studs that probably has more to do with the breakage than the washer.

Bobby

911pcars · 12-10-2002, 10:39 PM

Nice job. I suspect you made yourself comfortable on your back if it took you 3 hours. Most techs would have given up after the first .... 15 minutes. You show persistence and, at the same time, restraint in not bashing the hell out of the engine from the frustration level created from this dilemma. You've got my vote as well. Congratulations.

Here's one. What kind of head stud will you use to replace? A matching replacement Dilavar or an odd-ball steel one?

BTW, I couldn't tell from the pics, but what color are the Dilavar studs on your engine? Silver, gold?

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

john70t · 12-11-2002, 01:16 AM

A thousand words. Thanks again for posting this time saver and you get my DIY vote as well for not stripping the threads or cracking the case.

One question of the same note: how much concentrated heat can one safely apply to mag/aluminum heads without consequenses? It seems the fins would bear the brunt before it soaks in around the threads.