Badly seized engine bolt

[hawkeyefxr]

That was the first thing I did, I then welded a 4mm bit of metal onto a 10mm nut. Ground it down the the shape of the 10mm nut I can no use my air gun to hammer on the end of the 10mm stud without damaging the threads on the stud.
But no good, the actual engine lugs are quite small and have heard of broken cases, I do not want to go there !!!!!!

Like i said I will keep on trying the penetrating fluid and air gun but think it will need to be cut pff then drill out the seized part, but thats a winter job, plus we are in the throes of moving to Kent and I want to set up my new workshop (garage) as it will be a dual purpose place.
I do a bit of wood turning and make pens out of AK47 bullets.

[E-bmw]

Still not 100% sure what you mean.

Is the nut seized on the stud?

Is the stud seized to the bracket?

Is the spacer seized on the stud?

Is the stud seized into the engine casting.

[Krikkit]

E-bmw said:

Is the stud seized into the engine casting

This is the problem I think.

FWIW OP I've had very poor results trying to remove this kind of stuck fastener - the worst was an Alfa 159 front suspension knuckle, in the end the steel bolt was so stuck, and I'd heated the casting up enough that it simply fell apart.

It's an expensive option, but as you've tried pretty much everything you can I'd cut the bolt between the frame and the spacers, then get the casting down to a machine shop to have it drilled out.

Then on reassembly some proper anti-seize (not just copperslip) and a regular removal at service time, perhaps one to put on a little checklist for your annual oil change?

[njw1]

I've had exactly this issue when removing a diff from a Ford Sierra, there's a long through bolt that passes through the front of the diff to secure it to the sub frame. My solution was to cut the bolt to get the diff off the car and then with a bit of heat, various penetrating oils and tapping what was left of the seized bolt in both directions it eventually came out.

[hawkeyefxr]

Diffs are made of cast iron and can put up with a bit of knocking, this is a cast aluminium casing so knocking side ways is not a good idea.. The mountings are surprisingly small, later bike the cases were beefed up and two bolts were not one long stud.

Been for a run today got the engine good and hot then gave it a good squirt of penetrating fluid, tightened the nut on the on the seized side leaving it under tension.

[njw1]

The diff casing on a Sierra is aluminium, the through bolt is steel, hence it getting stuck. I didn't go mad with the hammering either, just a few light taps either way with a small(ish) hammer, I can understand why you wouldn't want to do it with an engine casing to be fair.
Anyway, good luck with it!

[hawkeyefxr]

njw1 said:

The diff casing on a Sierra is aluminium, the through bolt is steel, hence it getting stuck. I didn't go mad with the hammering either, just a few light taps either way with a small(ish) hammer, I can understand why you wouldn't want to do it with an engine casing to be fair.
Anyway, good luck with it!

Cheers mate, you know my reluctance for the hammering.