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MG MGB Technical - Head studs

What tips to get recalcitrant head studs out of the block?

The head gasket failed a couple of years ago and after failing to shift all the ones I tried with double nuts I gave up. Torquing back down I felt that a couple of them were starting to stretch as I approached the required torque, so kept it to a minimum.

While doing that job I found No.2 exhaust valve leaking, only fine marks on the surfaces but fuel seeped out, lapped them in for no seeping and everything seemed OK until the last couple of months when it started sounding a bit rough and a bit down on power.

The same valve is leaking again - head gasket itself seems fine, compression down to about 120 dry. So the head has to come off again, and I'll send it away for crack-testing and unleaded conversion this time, but I really don't want to use those same studs again.

So, how to get them out?
paulh4

I find that the double nut method usually works.

I have some Metro (A+) flanged head nuts, which lock together tighter than standard nuts. You are more than welcome to try them.

Failing that, stilsons will also get them out. They will obviously mark the shanks, but that shouldn't be an issue if you're replacing them.
Dave O'Neill 2

Thanks but these are flanged nuts, possibly because it's a Gold Seal. They locked together OK, but both turned on the stud. In fact I'm wondering if the friction between the flanges was preventing them tightening together as much as plain nuts would have, so gripping the threads less tightly. I'm pondering deep nuts, but obviously my ultimate concern is shearing one or more studs!
paulh4

I had a similar issue a couple of years ago when I wanted to get a rebore, I had 2 or 3 studs I couldn’t remove whatever I tried. The old boy who was doing the work felt confident he could remove them but if not he’d work around them, needless to say he got them out.

I’d tried various things including an extractor that fitted over the stud and used a knurled wheel that tightened onto the stud, they all failed. I prefer something that applies a rotational force without a sideways force unlike the typical locking spanners, molegrips etc. I also like to make conditions as favourable as possible. I’d get the block reasonably warm, nice warm garage in front of a fan heater and then try one of the freezer release sprays on the stud to try and shrink it.

http://www.screwfix.com/p/arctic-products-crack-it-shock-release-spray-400ml/83415

Failing that it might the justification I’d need to buy one of these.

http://www.bolt-buster.co.uk/#1
R.A Davis

What's locking the stud in? I assume its just been tightened to the bottom of the thread in the block.
To minimise twisting the stud, the application of the turning force needs to be as close to the block as possible so probably cannot use the 2 nut method to do this.
I don't know how much use heat would be but I tend to head any thread that is reluctant to move!
AdrianS

1/2 in drive stud extractor tool, located right down at the bottom of the stud.
If it doesnt work then you will need heat, and freeze spray.
if still no success then it is down to the machine shop, because you will probably have broken the stud.

It happens!
Colin Parkinson

If there's still some stud showing one can sometimes file a couple of flats on opposite sides - enough to get some grip with a Stilson, if not a small spanner. Of course the next scenario is the stud sheared off level with block - presumably only method here is to drill out with increasingly larger drill bits and then clean out threads with a tap, or next stage on, utilise thread insert.
Peter Allen

Paul if you can borrow one of these it will do the trick, the snap on one is the best, I have seen other cheap one and they are not a patch on this one, it will only heat up the part you want and it wont heat up the block, I have used it with great success on turbo studs and head suds, suspension bolts stuck in bushes,


Andy Tilney

I have yet to meet a stud that resists a 3 foot long stilson ...

and they tend to snap on torquing down not twisting out.

The length of thread in the block is only about 3/4 inch and coarse threaded, they won't have bottomed out.

Either they have been overtightened fitting them ( they should only be finger tight), they have rusted or they have been fitted with thread locker.

Just get a firm grip on the stud and apply steady force with the longest stilson, it needs to be self tightening, mole grips are useless.
Chris at Octarine Services

The stud removal tool that work well are
https://www.ebay.com.au/i/291811837274?chn=ps
the Japanese brand Koken are better
http://www.frankstools.com/koken-stud-puller-set--44211.html
They use three hardened rollers that lock against the stud like an overdrive sprag clutch, doesn't damage stud - 1/2" drive with sliding tee handle (plus pipe extensions if needed)


For sealing the head studs Wurth Flange Sealant orange (DOS system) is recommended.
Mike
Mike Ellsmore

Thanks, all thought-provoking. I wasn't planning on removing the engine so their wouldn't be enough room to wield a 3-foot Stillsons, and if it was out I presume it would need to be half-buried in the ground to stop it turning! Maybe just enough room for 2-ft. I can see drilling and re-tapping on the horizon - left-handed bits in case that helps get the remains out.

Or just replace the engine ...
paulh4

Best of luck Paul.

Be careful with left handed bits - if the stud is too tight to turn and snaps then there will be a very high chance that the left handed easy out bit will snap too! Never had much luck with them.
AdrianS

Paul
I don't know how good a shot you are with a hammer but this is how I get them out----
Thread your first nut down the stud ,then the second one till it is dead flush with the end of the stud, then while holding the top/second nut ,screw the first one up against it and tighten them against each other making sure the top one is still flush with the end of the stud. Then give the stud and nuts a good whack on the end, retighten the nuts against each other and screw the stud out.
If it doesn't loosen, give it another whack and try again--it will give in--
If you're not such a good shot with the hammer you can use a punch and hammer, but if you go that way make sure it's a decent diameter punch like 3/4" dia. or more--
willy
William Revit

Adrian - not an easy-out which I know can snap in seized studs, then it really is game over. I meant a left-handed twist drill bit - which can still snap of course, but more through poor manipulation than anything else. leaning into the engine compartment with a drill wouldn't be easy, could do with bolting down a pillar drill to the block ... which needs studs ...

William - that's a good one, I've used the same method for removing steering wheels. I'm not a good shot with a hammer where parting steering arms and track-rod ends is concerned, which is why I always use a scissors tool, but I should be able to manage with studs.
paulh4

Paul, I've had the head bolt snap INSIDE the block below deck level,as well as a head shear right off the the top during a head gasket exchange. It was on a 1975 Chevy straight 6.I discovered the broken bolt by comparing the length of the others.

Removed the broken piece by filling the threaded hole with pentrating oil (Liquid Wrench) over a period of several days. Was able to drill into the broken bolt far enough to get an easy out inserted into the drilled cavity. Worked the bolt counter-clockwise and clockwise to free it up. It took a lot of time to do this, but got it freed up and out.

Replaced all the bolts with a higher grade rating.

Cheers

Gary
79 MGB
gary hansen

2 1/2 hours from starting to drain the coolant to getting all the studs out. I doubt that would have happened without the £20 Laser extractor and the air-gun (or an impact wrench), but some needed quite a bit of chattering before they moved.

Next step head check, and if that's OK unleaded conversion.
paulh4

Paul.I've never seen a laser retractor. Do you have a pix of it?

The bolt in the straight 6 Chevy that snapped off inside the block was "in there" tight. Again, after much dousing with pentrating oil and air blasting, it loosend up enough to be worked slowly out with plenty of counter-clockwise and clockiwise movement. It took several days of prep to get the bolt to move at all. That bolt was recalcitrant in every noun, adverb and adjective form.

Oddly, it had a torque spec of 105 lb/ft. A few inquiries confirmed it was indeed true. Replaced all the bolts with grade 8's and spread a light film of Permatex anti-sieze compound on the threads.

Cheers

Gary
79 MGB
gary hansen

Paul, are these the extractors you used
http://www.lasertools.co.uk/product/3734
Mike
Mike Ellsmore

'Laser' is probably a bit misleading, not something really sophisticated and electronics based, just a trade name :o)

https://tinyurl.com/y7p8omhw Similar to a drill chuck, tighten by hand, then apply impacts.
paulh4

Ok. I thought is was some latest innovation using laser to "do something" to a recalcitrant bolt. From the https:// you,ve posted, those tools would not have helped my situation at all. The bolts in question were, IIRC,had a 5/8" head. The broken piece was in the block approximately a good 1" to 1-1/2"+ deep. The broken piece when finally extracted was about 1/4" long.

Cheers

Gary
79 MGB
gary hansen

Indeed, although I'm aware of a spark erosion or metal disintegration process where pieces are left inside holes. Primarily for removing broken taps or EeziOuts (!) where drilling is not possible due to the hardened nature of the offending piece https://www.youtube.com/watch?v=YbeKxFBZrF8 Goes on a bit but a good description.
paulh4

I have successfully removed broken easy outs by just mig welding down the hole - the easy out remnants shatter under the heat and come out in bits, the heat also loosens the jammed stud end.

I find it much easier to just drill out a broken stud and retap or fit a helicoil.
Chris at Octarine Services

I use heat=expansion, cool=contraction to remove stubborn bolts/studs. Soak with a good penetrating oil for a day or two. Heat the stud to a dull red with a welding torch; give it a sharp, but not too hard, crack on the top with a hammer. Let it slowly cool completely then give it another crack. Now heat the block until it just too hot to touch and then spray freeze the bolt. Use a good extractor and it should come out, if not repeat. Works for me . . .
Jc
John Crawley

The double nut method almost always works, but in some cases the hammering of an air wrench on the double nuts can shock the stud enough to get it moving when a constant pressure wasn't working.
Bill Spohn

This thread was discussed between 03/01/2018 and 28/01/2018

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