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MG MGB Technical - &&B stud broken off in exhaust mainifold

I have 77 B and while replacing the gasket between the exhaust manifold and converter I decided to replace the three studs in the manifold as they were worn. I got the first two out no problem with a socket stud extactor but the third closest to the engine has snapped off in the manifold. There is about a 1/4" of the stud protruding from the manifold front side closest to the radiator. Any chance of getting this thing out without removing the carb and manifold? I would be working from the front side of the engine as that is the side there is some protrusion on. Any hints, thoughts, suggestions and directions would be deeply appreciated. I have been having quite a go around with the converter gasket blowing and was refreshing everything front to back to eliminate the problem and now this. Thanks for your ideas in advance.
JCH Hibbard

Not sure I am picturing it properly in my head but could you make a small metal plate maybe 1/4 thick with a hole in the middle that the stud fits into. Put the plate over the stud and MIG weld the stud to the plate. Then just turn the plate to extract the stud. The heat from the welding should also help break the threads loose.

Simon
Simon Jansen

The protruding part of the stud is on the backside of the manifold facing the radiator and out of the three studs that anchor the converter to the manifold it is the one closest to the engine. Whoever fit the studs into the manifold previously must have used a slightly longer stud screwing it all the way thru leaving about a 1/4" protrusion on the backside. That's what I'm hoping to be able to work with without having to remove the entire manifold. Welding a nut on might work but I do not have welding tools unfortuneately.
JCH Hibbard

Oh yes JCH, this is a job that is a lot of fun! The ONLY way that I will try this is the way the old, old man showed me years ago. I had the same problem you do to the T. I put heat on it & still no go. Went to my buddy Teds & showed this 65 year old man the mess I was in, he looked at it & said no problem. I had a new set of vice grips & had not rounded off the stud sticking out the other end of the manifold (raid. side), He got his torch out & put a lot of heat to the aera around the stud & got it RED, thin droped it in a 5 gal. pail of water! I knew that the cast iron had shattered, with it that hot! He left it in the water for 4-5 min, pulled it out of the water & spun it out with a pair of plyers! I said TED WHAT DID YOU JUST DO????? He said, just heat will not do it, you have to hit it hard with cool water & sometimes you can take the stud out with your fingers, & he said he has been doing it for years! Well I have been doing this for 36 + years & have not cracked a cast iron manifold yet! Every now & thin I might have to heat it up twice & put it in the water twice & one time I did it 3 times, but I got it out! Thanks to the BEST TEACHER I have ever had! Ted Wallace 1902-1991
Glenn Towery

I think removing it on the car may be a bit ambitiuos. I sheared one off once (correct lenght) and took the manifold off and drilled through the centre then turned it out with mole grips on the stub, plus some penetrating oil.
Stan Best

I agree, space is pretty limited for getting at some of the studs in situ. At the very least the rest of the exhaust will need to be dropped and moved out of the way. Once the manifold is off the car it is a relatively easy job to drill and retap. I had to do this to one stud during a recent clutch change. I drilled a small hole through the remains of the stud to check the alignment at both ends, opening out the hole as required to get it centralised. Then drill to the size for the tap, then taper tap then plug tap. Because you have a stub the heat from drilling the first hole may allow you to screw it out with grips. Personally I think stud extactors are dangerous when used on siezed studs or stubs of bolts, I have heard of too many snapping off in the hole, then whatever the stud is siezed into is scrap, pending spark erosion anyway.
Paul Hunt

I tend to agree that the manifold will probably have to come off. In the next couple of days I am going to try a couple things first with it on then when I have a few hours to spend get it off if I have no success.
JCH Hibbard

Well.

Go to an old experienced muffler shop. They will heat that stud until it almost melt away and cast iron will be unaffected.

Cheers,

JGC
Jean Guy Catford

Just wanted to thank everyone for your ideas. After heating, drilling, failed easy out attempts and even trying Glens heating and cooling in water it came down to drilling out the stud and retapping the hole. The old stud is out the new one is in and tomorrow is re-assembly. Thanks again for all of your help.
JCH Hibbard

This thread was discussed between 06/07/2008 and 13/07/2008

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