head studs
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Joined: Feb 2003
Posts: 78
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From: Edinburgh/UK
head studs
Following dropping the engine and pulling it to pieces to repair 3 snapped (lower) head studs, I find I'm really fighting to get the studs out. I've tried all the normal tricks, and broken 2 extractor tools already. I've bought a heavy duty stud extactor and am using a 3 foot power bar, but the b****rs just don't want to budge. I've tried heating them, tapping them, soaking them in penetrating oil, but about half of them are refsung to turn. And this is before trying to remove the one that are snapped close to the block.
Any bright ideas, or is it time to visit the local machine shop?
cheers
Matt
1980 3.0 SC
Any bright ideas, or is it time to visit the local machine shop?
cheers
Matt
1980 3.0 SC
Instructor
Joined: Apr 2002
Posts: 126
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From: SCWDP Bunker
I hope John Walker will chime in here, but you must use plenty of concentrated heat. You are attempting to melt the Loctite that is on the stud threads. The case is a big heat sink, so you have to apply a lot of heat. The correct place is right where the stud goes into the case, *inside* the spiggot. Do not heat the stud. And really, only an Oxy-Ace torch (with a mild tip) can supply enough heat to do the job. It sounds frightening to use the torch, but it works.
On studs that are broken flush, you may have to rely on a Porsche specialist machine shop. The Dilavar studs are very hard, and will resist drilling.
On studs that are broken flush, you may have to rely on a Porsche specialist machine shop. The Dilavar studs are very hard, and will resist drilling.
AutoX
Joined: Jun 2002
Posts: 13
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From: Sydney, Australia
I had this problem on my 3.0 SC engine, and needed to have the broken stud removed by a process known here in Aussie as 'spark erosion'.
Basically the broken stud can be spark eroded away, and the case being aluminium is not damaged. It is a safe alternative and was fairly cheap.
Maybe just find an engine shop who can do this. Commonly needed in Aluminium engine blocks I was told.
Good luck.
Bruce
Basically the broken stud can be spark eroded away, and the case being aluminium is not damaged. It is a safe alternative and was fairly cheap.
Maybe just find an engine shop who can do this. Commonly needed in Aluminium engine blocks I was told.
Good luck.
Bruce
Instructor
Joined: Jul 2003
Posts: 117
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From: North of Boston, MA
"spark erosion" is called EDM or Electrical Discharge Machining in the states. It uses an electrical spark to vaporize the metal. It is not too expensive to have done but not every shop has the equipment.
IMHO I would go with the heat first before you look into EDM.
IMHO I would go with the heat first before you look into EDM.
RL Technical Advisor
Joined: May 2001
Posts: 11,870
Likes: 75
From: Portland Oregon
Hi Matt:
Lots of heat applied at the base of the stud and into the cylinder spigot will do the job every time. Patience is a virtue, here,....
We use an oxycetylene torch but a Mapp gas torch will do the job if you are patient. Don't forget, the case acts as a big heat sink and its takes time to get the metal hot enough to melt the loctite holding the threads of the stud.
Lots of heat applied at the base of the stud and into the cylinder spigot will do the job every time. Patience is a virtue, here,....
We use an oxycetylene torch but a Mapp gas torch will do the job if you are patient. Don't forget, the case acts as a big heat sink and its takes time to get the metal hot enough to melt the loctite holding the threads of the stud.
