Stuck cylinder head stud

[ssplant]

OK so after several week of freeing agent, broken stud extractors and a sprained wrist I give up. I have one cylinder head stud that won't come out, one of the two deep ones with the thread 4" down in the casting. even with 3ft or tubing on my t bar and a 7lb lump hammer it won't shift. I would appreciate any ideas or secret spells that I might use - to late for tearing the hair out though! Cheers Simon

[barkerwilliams]

Simon,

 

Have you seen this site?

 

http://www.sparkeroding.co.uk/

 

 

Alan

[RogerH]

Hi Simon,

what engine are you working on?

Which stud is it?

How much stud is showing/remaining - good description please

 

Are the broken stud extractors (easyout etc) still stuck in the stud.

 

If it is just a stud down the hole then how about drilling out as much of the remains as possible.

Then either trying to put another extractor into it, or unpick the remnants with a pointy thing, or put a tap down the hole.

 

If the thread gets damaged then we are into 'helicoil' territory - not a major disaster.

 

Roger

Edited November 24, 2016 by RogerH

[DaveR]

 

If the thread gets damaged then we are into 'helicoil' territory - not a major disaster.

 

Roger

 

Had to helcoil the stud threads in the block on a Standard Triumph engine 2.5 six. No problems. It still around 20 years on. Not good for your state of mind when it happens, but the helcoil fixed it.

 

Thanks,

Dave

[Motorsport Mickey]

You don't say what you've been doing with the lump hammer ! If you been beating on the T bar nope that won't work, if you've been belting down on the top of the stud well it's a better idea but if you have an air chisel and blunt the end and try bearing down on the stud with a few Bbrruupp Bruupp after further treatment on the stud it may loosen it.

 

Have you got the stud cherry red with a welding torch and then tried 2 locked nuts or another turning tool on the stud ? Then try again with air chisel. You say releasing agent has been used but not what it is, my experience is very little is as good as diesel, if you've not tried build up a reservoir around the stud and flood it with diesel, if it all stands on top try a couple of applications of the air chisel, once you've got it to start searching it's way through diesel doesn't stop and it remains lubricating surfaces for weeks afterwards. You've got to break the corrosion seal, time is on your side if you can stand it.

 

Mick Richards

[ssplant]

A bit more information for Roger. It's the 2nd stud back from the front on the off side of the engine. It is still intact and full length. It's one of the two really long ones where the actual thread is well down in the casting. The stud extractors I have broken are the cam type ones that slip over the top of the stud that get progressively tighten as the knurled wheel rotates as a cam. Hope this helps. Its a TR4 engine, new to me and sump still on so haven't tried to look if you can get at this stud from the bottom inside the crankcase, can you? Cheers

Simon

[john.r.davies]

+1 for heating the stud, but not for double nutting.

WELD a nut to the top of the stud, getting it really hot, glowing.

Then turn this fabricated bolt out with a sockst and breaker bar, by tightening it first, working it both ways as you take it out.

it will need replacing anyway!

 

John

[RogerH]

Hi Simon,

welded nut on top is a good one to get purchase.

If you do heat to cherry red do not turn the stud whilst still red - it will simply twist.

 

No access from beneath.

 

Definitely try tightening a touch before undoing.

 

If everything fails - but before the stud snaps - you could cut the stud down to apprx 1/2" or so then weld the nut back on.

This will help remove any spring from the long stud and may help break the grip.

Or before the welded nut you could drill all the way down the centre (use a centring guide) - open the hole to 3/'8 or 7/16 and try to undo.

 

Roger

[littlejim]

In amongst the other stuff you could try Dave Connitt's suggestion of melting candle wax down the thread.

It worked for me on a couple of reclcitrant studs, - sounds like you've got a ripper though.

Might have to use one of the 'heroic' solutions above if the wax doesn't do the job.

Edited November 25, 2016 by littlejim

[Motorsport Mickey]

HHhmmmmm I've heard of the hot wax system but as I remember it involved a disproportionate amount of pain and suffering before it achieved "release".

 

Mick Richards

[RogerH]

Hi LJ,

The stud threads down inside the block are always covered in crud when removed I don't think you will get wax into them.

Also there is a massive heatsink - the wax would set pretty quickly.

 

I still like the shortened stud/ welded nut - apply release force and whack the stud vertically hard with a hammer

 

Roger

[littlejim]

Hi LJ,

The stud threads down inside the block are always covered in crud when removed I don't think you will get wax into them.

Also there is a massive heatsink - the wax would set pretty quickly.

 

 

Roger

Theory is one thing, doing it sometimes gets a different result to the guru's prediction.

The beauty of it the technique is it is so simple to try, and if it fails you can stil do all the heroic stuff later with no ill effect.

Worked for me.

[RogerH]

Hi LJ,

yes, you are quite right. If all else fails then go for it.

 

Roger

[boxofbits]

I'd be suprised if you could get the stud cherry red with heat, and certainly not uniformly all the way down the stud where it's needed as the block is a huge heat sink. I think you'd just end up twisting off the top of the stud.

 

It will probably be constant vibration from tapping with a hammer and plenty of releasing fluid that will eventually shift it. Failing that, a machine shop will have to drill it out and as has been suggested, a helicoil thread, though if it's a long thread that's going to be some helicoil. If you tighten a nut on the stud to 'pull it' and then hit it to 'push it' you may eventually have some luck, but it's definitely a difficult one!

 

Kevin

[Hamish]

Fuzz Townsend did something like this on a car SOS episode (just the stud not the block as well as in this clip ?!,!?)

Guess it won't be cheap. But may be able to hire something ?

 

I hired an impact wrench for one stubborn nut and job done in 20 seconds. But that was after trying every lever bar and extreme methods without success

Worth every penny !!

Edited November 26, 2016 by Hamish

[stillp]

I'd be suprised if you could get the stud cherry red with heat, and certainly not uniformly all the way down the stud where it's needed as the block is a huge heat sink. I think you'd just end up twisting off the top of the stud.

 

 

Easy to get the stud cherry red, just use an arc welder to weld a big nut onto it.

 

Pete

[RogerH]

Hi Kevin,

the longest Helicoil (generally) is 3xDiameter. But there is nothing to stop you puttin gmore than one helicoil down the hole.

 

Roger

[Chilliman]

 

 

But there is nothing to stop you puttin gmore than one helicoil down the hole.

you sure about that Roger?

[foster461]

I would go for the shortened stud, welded nut and an impact wrench. The electric impact wrench that I have would not put a lot of torque into the stud but it would break the bond in the thread with the constant frigging hammering.

 

Stan

[RogerH]

Hi John,

when you break off the tang at the bottom of the helicoil (for tightening into the hole) it leaves a clean spiral.

The next coil will sit nicely next to it. A small gap will make no difference

 

Roger

[stillp]

Yes Roger, but will the threads be continuous?

 

Pete

[RogerH]

Hi Pete,

they do not have to be. As long as the thread allows the stud to run down the odd small gaps make no difference.

The extra gripping effect of a helicoil more than compensates for any small gap.

 

Roger

[stillp]

I understand about the gaps, but unless the threads line up, a screw in the upper Heli-Coil will not engage the thread in the second one?

 

Ah, I've just realised they'll be constrained by the external thread.

 

Pete

[ChrisR-4A]

Studs that I have seen helicoiled have only had or needed the one helicoil fitted at the top. You only need the mechanical retention to equal that of the nut at the other end of the stud.

 

More to the point, where are you, there must be someone not too far away with an impact wrench. If not take the block down to your local friendly tyre fitter and use theirs.

Chris

[Paul J]

Personally I see no reason not to fit two helicoils in a tapped hole for a better fix as the coils will follow the TPI of the helicoil tap, I have done it many times. A well proven repair method, and theoretically stronger than original.

Best of luck

Paul