Cant undo my crank nut

ok i got the hint my air gun wont shift it and me bar on the nut with some scaff bar while some one had there foot on the brakes and still couldnt undo it.

unplug the stop solenoid, get the bar wedged under the offside chassis rail, then touch the starter.
it'll bang like a gun when it goes!

thats just sounds so rough

'Appen so, but it works.

ok ill go for it. ill let you know

We had the same probs on a disco. We had a 4 foot scaffold tube on the end of a bar and still would't budge. We broke a cheapo bar half inch bar and a snapon half inch bar doing it the way Treworgey says but it works. (The difference in strength was not much at all IMO) In the end we had to get the 3/4 set out and use the same process. LR cannot afford for the crank to fall off. It happened alot on the old 2.5Na and 2.5TD's from the factory and wrecked many many cars and LR had to call them all back in to do them all again. Jai

Treworgey 90 said:

unplug the stop solenoid, get the bar wedged under the offside chassis rail, then touch the starter.
it'll bang like a gun when it goes!

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This is the way to go .... with great care.

Make sure the lever is firmly wedged against (UNDER) the DRIVER's side chassis else it will give something a Hell of a whack.

Make sure the engine WILL NOT START!

Good plan is to take out the glow plugs (you need new ones anyway) thus killing the compression, making it easier for the starter motor to work its magic, and making very sure the engine will not fire up.

The starter motor alone can apply a HUGE torque for a short time, and when its little pinion meets the big ring gear that multiplies its torque about 40 times. The nut really should come loose for you.

If you can get at it, giving the pulley bolt half a dozen good smacks straight back with a two pound hammer might help it to be less stubborn.

CharlesY

i,m a bit interested in this thread,with a camshaft job on the way i,ll be tackling the dreaded crankshaft nut myself but what about tightening the nut up afterwards i believe it has to be about about the 240nm mark(is it a good socket and lump hammer job)

bart2181 said:

i,m a bit interested in this thread,with a camshaft job on the way i,ll be tackling the dreaded crankshaft nut myself but what about tightening the nut up afterwards i believe it has to be about about the 240nm mark(is it a good socket and lump hammer job)

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Re-tightening is never the problem.

It's cracking the bugger loose that causes all the trouble.

NEVER tighten things with a hammer to tighten them, that's my advice.

Undoing things is quite different. If you can't shift a tight one, get as much loosening torque on it as you can, and while holding that "off" torque give it a good smack in the off direction with a two-pound hammer. Just take care not to smash anything to bits.

240 nm is about 180 foot-pounds - easy enough with a two foot bar and a good steady pull, especially if the threads are CLEAN and lightly greased. Remember, the actual TORQUE is not what you are trying to achieve here. Torque is only a method of setting the TENSION of the bolt or stud LONGWAYS, like trying to stretch it. If the threads are greased with molygrease, the same torque will produce nearly TWICE the tension as dry threads. This is almost always good.

CharlesY.

CharlesY said:

Remember, the actual TORQUE is not what you are trying to achieve here. Torque is only a method of setting the TENSION of the bolt or stud LONGWAYS, like trying to stretch it. If the threads are greased with molygrease, the same torque will produce nearly TWICE the tension as dry threads. This is almost always good.

CharlesY.

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Incorrect.

A torque setting (ie: 240 nm) is the rotational force applied to the bolt, the bolts longitudinal force is controled by the pitch of the thread and the rotational force of torque applied to it .

If the threads are lubricated before assembly, when they should in fact be assembled/tightened in a dry state, the frictional force between the threads (crankshaft/pulley bolt) will be greatly reduce allowing the bolt to rotate further, allowing the bolt to apply a much higher longitundinal force.

Some manuals will state two torque setting for the same bolt, a dry torque figure and a lubricated figure, the dry figure is always higher due to no lubrication...

The torque setting plus thread pitch allows the designer to control the longitundinal stretch of the bolt, if a bolt passes it mechanical optimum stretch point, it looses it ability to apply the longitundinal force required. Hence stretch bolts that are a one use item..

well now you,ve lost me,all i want to know is a good simple method of re-tightening the crankshaft pulley bolt,anyone out there with a good non-scientific answer please reply.cheers

bart2181 said:

well now you,ve lost me,all i want to know is a good simple method of re-tightening the crankshaft pulley bolt,anyone out there with a good non-scientific answer please reply.cheers

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Hire or borrow a torque wrench...or do it up F.T.

zzr1200 said:

Incorrect.

A torque setting (ie: 240 nm) is the rotational force applied to the bolt, the bolts longitudinal force is controled by the pitch of the thread and the rotational force of torque applied to it .

If the threads are lubricated before assembly, when they should in fact be assembled/tightened in a dry state, the frictional force between the threads (crankshaft/pulley bolt) will be greatly reduce allowing the bolt to rotate further, allowing the bolt to apply a much higher longitundinal force.

And in't that EXACTLY what In just said?

Some manuals will state two torque setting for the same bolt, a dry torque figure and a lubricated figure, the dry figure is always higher due to no lubrication...

The torque setting plus thread pitch allows the designer to control the longitundinal stretch of the bolt, if a bolt passes it mechanical optimum stretch point, it looses it ability to apply the longitundinal force required. Hence stretch bolts that are a one use item..

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So having writ all that what is wrong with what I wrote?

I can tell you for almost every sort of oil and lube by how much TENSION is increased for the eame torque in the same appliaction.

DRY threaded bolts COME LOOSE SOONER, because there always is a risk that between the threaded end and the head there remains TORSION in an UNLOOSENING direction. The longer they are the WORSE the risk is.

PLEASE BE TOLD. This can be very dangerous indeed.

In general principle, ALWAYS apply coppergrease or similar AND do NOT exceed the stated torque settings unless you have a good reason to do so.

CharlesY

Didn't the cleaver man from LR apply copper grease to the oil pump bolt (that had locktite already applied) as it was hard to get the bolt in, Lots of TD5's now with loose oil pumps moral of the story Things are made for a purpose don't feck with them!

I have a torque wrench that goes up to 400Nm, if anyone local needs to borrow it.
It's nearly 6ft long though!

CharlesY said:

DRY threaded bolts COME LOOSE SOONER, because there always is a risk that between the threaded end and the head there remains TORSION in an UNLOOSENING direction. The longer they are the WORSE the risk is.

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In almost 40 years as a trained commercial vehicle mechanic, I've never known a head bolt/main bearing cap bolt/big end cap bolt come loose because it been installed dry, I have used oil/copper-slip but only where the manual has stated its use.

I have known, bolts strip/pulled threads in engine blocks because the bolt has been done up to tight as probably have you also.

Lock-tight sealant is also stated in a number of manuals on other bolts and should be classed as a lubricant.

CharlesY said:

PLEASE BE TOLD. This can be very dangerous indeed.

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Yes, I agree not following the manufacturers stated procedure is dangerous

CharlesY said:

In general principle, ALWAYS apply copper-grease or similar AND do NOT exceed the stated torque settings unless you have a good reason to do so.

CharlesY

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So what do you do if the manufacturer states that "All torque figures are for dry threads"...???

Plus when I was an apprentice we were told that all torque figures were dry unless otherwise stated, which I've always found to be true as manuals will usual state, lubricated thread before instaling...

well iv got the nuts of now thanks to knowing the meaning of torque and dry and lubed bolts

It would be time for the Snap-on book to come out and a multiplier purchased to be attached to the end of your 3/4 bar if you were still stuck but well done how did you finally do it?