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MG MGB Technical - cylinder head stud

Hi, I am having a problem removing a damaged head stud from the engine block, its the center one on the spark plug side of the block. I have tried the double nut trick and also warming it and soaking it with penetrating oil but it refuses to unscrew. Any suggestions would be welcome.
Robert Lester

That's a bit scary. Sometimes you can start a stuck thread by tightening it then loosening. In this case the problem may be that the stud was bottomed in the hole so I wouldnt push it too hard. A a chunky Stiltson will get you more leverage, I've got an 18" one and its got me out of jail a few times. The thread would not survive this treatment though, possibly this could also shear off the stud. When you heated the block did you attempt to loosen it while it was still hot? I imagine the engine is still in the car, the ultimate way out would be a pillar drill and either re-tapping or a helicoil insert.
Stan Best

Try MIG welding a bead or two on the stud, close to the block. shield it with some 1/8 Masonite. This will get the heat deep down the hole. Then the bead will enable those Stilsons to grip.
Art Pearse

Hi Robert
When i could not get mine out without a lot of trouble I left it in and replaced the head and gasket
no problems in 3 years since
D DODDS

Robert, how damaged is this stud?
Art Pearse

Hi Art Pearse, the damage is to the top thread, the area where the nut fits to hold the head down. Even then its only to the top third of the thread that is slightly weak. I have eased a thread die down it with the die holder adjustment screw screwed right in and then reset it and screwed it back up which cleaned it up nicely. It looks good but I fear that when it comes to torquing it down it will finally slip. Unless it comes out soon I will probably just try it and see if it holds.
Bob Lester

Robert-
When working on an engine that is at least 30 years old, it is not uncommon to encounter a stud that refuses to come loose. Most owners simply douse the offending stud with penetrating fluid and let it soak in overnight. The following morning, two nuts are then placed on the stud and the bottom one used as a jam nut so that the stud can be turned. All too often, the tired old stud breaks off, usually at its juncture with the engine block. This unfortunate cause of much foul language can be avoided. An 'Ol-Timey-Mechanic’s little-known trick that works quite well is to heat the stud / engine block area as hot as you can get it with a torch, and then touch the junction of the stud and the engine block with candle wax (I use leftover little birthday cake candles for this) until you have a puddle of wax around the stud, then let the area cool a bit. The heat-thinned wax seems to seep down along the threads as the area cools and lubricates the stud so that you can back the studs out.
Stephen Strange

THIS SHOUKLD WORK.. HEAT THE STUD UP AND THEN APPLY THE HOMEMADE PENETRANT. ATF/ACETONE IS THE ANSWER

Here is a comparison of penetrating "oils". Hope this helps.


Machinist's Workshop magazine tested penetrants for break out torque on rusted nuts. They arranged a subjective test of all the popular penetrants with the control being the torque required to remove the nut from a "scientifically rusted" environment. The results are as follows;

Penetrating oil..... Average load
None ..................516 pounds
WD-40 ................238 pounds
PB Blaster ............214 pounds
Liquid Wrench ..... 127 pounds
Kano Kroil ............106 pounds
ATF-Acetone mix....53 pounds

The ATF-Acetone mix was a "home brew" mix of 50-50 automatic transmission fluid and acetone.

darnoc31

This thread was discussed between 25/02/2012 and 27/02/2012

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