I have this harmonic balancer bolt giving me tremendous amounts of grief...

[4th surf]

Make that with a spare spanner and pipe

I have broken those on crank bolts esp on 1UZs, JZs plus KZ and KD diesels which all use a high torque setting on the bolt. Never got one undone with a rattle gun unless it hadn't been properly tightened in the first place and this does include getting the "Fleet service tyre guy" around with his "Big arse rattle gun and compressor". A good quality breaker bar with impact socket on the end of it with the bar about 100mm from a chassis rail in direction of engine rotation and a "Flick" of the starter has never failed me but with one exception which was where some "Numpty" had butchered the bolt before it was bought into my shop. In that case the bolt had to be drilled out and replaced. Do not apply any heat no matter the circumstances. In the very worst case which I have dealt with which was on a Honda (engine turns in opposite direction) I had to remove the sump and lock the crank with a block of wood as a replacement crank bolt was not readily available. This was on a 5 cylinder Accord

[JadeEstevez]

Why no heat?

Also, Whats the chances of breaking teeth on either the flywheel or the starter motor?

[dnegative]

Never got one undone with a rattle gun unless it hadn't been properly tightened in the first place

Its a 22mm bolt done up to 300Nm, if your 3/4" gun cant get it undone toss the fucker in the bin because its rubbish, even my 1/2" one handles them.
I've got one of those titanium cased Chicago Pneumatic ones and it undoes 700Nm 30mm wheel nuts.

[dnegative]

Why no heat?

Use heat, your mainly heating the bolt and you don't need to get it cherry red.
Little bit goes to the pulley and crank but its not enough to damage or hurt it.

I've seen teeth snapped off ring gears and alloy bell housings cracked around the starter from where a bar has been left on the pulley and the motor cranked...... and every second Cummins engine also seems to of had a timing pin snapped in it too

[LittleRedSpirit]

What temp do crank bearings melt at?

[JadeEstevez]

Damn... I'm getting so many conflicting answers... Well, I'm not keen on cranking the engine over with the bar on it, In my opinion, Its just as dumb as undoing the nut retaining a spring on a strut without a compressor and hoping for the best.
I'll try heating and freezing the bolt. I won't get the thing red hot, Just enough to make it expand and shrink that little bit to crack it easier. Doesn't matter about the seal in the timing cover melting, I have two brand new ones

[JadeEstevez]

What temp do crank bearings melt at?

The heat won't be near a crank bearing anyway, It'll be concentrated on the bolt which is quite a distance from the front bearing

[dnegative]

What temp do crank bearings melt at?

The babit probably goes at 400+
Your not going to damage the crank or the bearings with some isolated heat on a bolt head. It doesn't get hot enough. You would have to have the entire front of the engine alight with a big oxy rosebud to get the crank hot enough to melt bearing shells. You would replace the seal and timing belt as a precaution though.

[JadeEstevez]

18RG = Timing chain I'm safe.

[4th surf]

Use heat, your mainly heating the bolt and you don't need to get it cherry red.
Little bit goes to the pulley and crank but its not enough to damage or hurt it.

I've seen teeth snapped off ring gears and alloy bell housings cracked around the starter from where a bar has been left on the pulley and the motor cranked...... and every second Cummins engine also seems to of had a timing pin snapped in it too

Yes and I've seen the "nose" snapped off of a crank as heat has been applied. More so on marine diesels but also in automotive applications

[JadeEstevez]

Well I'm more inclined to altering the temperature of the bolt then cranking the motor over with a break-out bar on the bolt...

I'll let everyone know how it goes today

[Dazza]

Make a tool to stop the harmonic balancer turning. I made one for my 3SGE engine in my celica. I used a bit of 10mm plate about 80mm wide by about 120mm long and welded a bit of square tube to it for a handle. Drill two holes in the plate to line up with the threaded holes in the balancer and a big hole in the middle to alllow your socket to go through onto the bolt on the end of the crankshaft. Bolt the tool up so the handle hits the ground when you try to undo the bolt in the center and then use a breaker bar with a bit of pipe over it to undo the bolt.

[GT1978]

Damn that bolt sounds pretty fixed. I have the opposite problem in that my 18RG crank pulley bolt keeps coming loose.
For stuck bolts heat is your friend. And maybe the freeze spray stuff also. Just try and keep the heat on the bolt and not all the surrounding ancillaries. The temp change expands / contracts the bolt at different rate to the crank threads helping to break the bond.

Glen

[maj]

My 1/2" SCA spec air impact driver couldn't do it

Got a bigass screwdriver I didn't care about bending, stuffed it in the flywheel teeth, then just used a breaker bar with a bit of WD40 on the bolt, and got it undone once I had a good hold on it.

[JadeEstevez]

My 1/2" SCA spec air impact driver couldn't do it

'SCA' as in SuperCheapAuto??

If so, There's your issue