Crank Pulley flew off!

[Tootall]

My son was driving the 1275 Minor on Sunday and called me from the side of the road, where he'd broken down.

Turns out the bottom pulley (crank pulley) had dropped off the car, at speed.

He was on a dual carriageway with a 60 limit but amazingly, found the pulley... and the bolt to hold it on was sitting on the panel under the radiator!

Do I just bolt it back on?

And, if so, how on earth did it manage to undo itself, in the first place?

My slight worry is that the collar (neck, whatever) of the pulley has split - would it work as a temporary fix or do I need a new one immediately?

This pulley looks different from the one on ESM (which is out of stock anyway - would a lightened, balanced 1275 engine have a special pulley (harmonic balancer or something?)

Pulley 1.jpg (3.79 MiB) Viewed 1212 times

Pulley 2.jpg (2.23 MiB) Viewed 1212 times

Pulley 3.jpg (4.96 MiB) Viewed 1212 times

[philthehill]

Do not refit the pulley - scrap it and put a new or S/H pulley on the engine.
I would replace the bolt at the same time make sure that you have the correct bolt for the pulley. There are two bolts, one with a dimple in its centre and one with a flat top. The one with the dimple should be used with the harmonic damper. You can also if preferred use the Minor starter dog instead of the bolt.
Instead of the standard bolt I use a cap headed bolt (as link below) loctited in place.
http://www.minispares.com/product/Class ... o%20search
Make sure the threads inside the nose of the crankshaft are o/k.
I would replace the woodruff key/
The cracked pulley shown is a harmonic damper. The only other harmonic damper is the two piece Cooper S two piece damper which has to be balanced as part of the crankshaft assy balance.
You could look on 'e' bay but make sure that the rubber insert of the damper is not cracked.
Here is what appears to be a reasonable pulley. You will have to remove the timing disc by drilling out the three rivets.
https://www.ebay.co.uk/itm/126019474551 ... R9jztt-xYg
Tap the holes and you can use a harmonic puller to remove the pulley.

Damper puller.JPG (873.97 KiB) Viewed 1192 times

[geoberni]

Excuse my ignorance on the subject, but why does that 1275 pulley not have a locking tab under the nut?

Does having a 'lightened, balanced 1275' do away with common sense locking systems?

Just curious.

I must admit I was surprised, when removing the pulley on my 1098 last week, to find the locking washer on the pulley was bent up on 2 sides to hold the starting dog Bolt, but the other parts of the washer hadn't been tapped into the 2 depressions on the pulley....

Heavens know how many years it's been like it, potentially around 25 since the engine was fitted...

[kevin s]

I'm probably missing something but where is the slot in the pulley for the woodruf key?

if there's no key I'm not suprised it's come undone.

[philthehill]

I suspect that the lock washer was there but got lost when the pulley became detached from the crankshaft.
There are two types of locking washer for the crankshaft bolt/starter dog. The flat type and the cupped type. Either can be used to secure the crankshaft bolt/starter dog. Both types require at least one knockdown into the pulley half-moon recesses and one knock up against the side of the bolt/starter dog..
Having a lightened and balanced 1275cc engine does not do away with common sense locking systems.
The Woodruff slot is there if you look carefully but is filled with crud. If the pulley is going to crack/split and in this case it did it will go from the root of the woodruff key slot.
The nose of the crankshaft needs to be checked for damage but the pulley metal is usually softer than the crankshaft metal and therefore usually survives unscathed. I had a similar thing happen soon after purchasing a S/H Landrover. I was able to purchase a NOS pulley and Woodruff key and when refitted was perfectly ok. The Landrover is still going strong.

[geoberni]

Thanks Phil, so presumably the lock washer can't have been correctly knocked into place.... a bit like I found mine.

[philthehill]

If the pulley cracked the lock washer would not save it.
Once cracked the fit of the pulley on the crankshaft nose would be lost and inevitably the bolt would become loose and then it is all down hill from then.
I think it has to be accepted that the pulley cracked and the above photos show the results.
There is very little thickness of metal from the root of the Woodruff key slot to the outer face of the part of the pulley on which the seal rubs.
The seal in the timing cover needs to be replaced as the lip passing over that cracked rubbing face will have done it no good.

[geoberni]

A detailed explanation of how such failures can happen. Thanks Phil.

[myoldjalopy]

Yes, I suspect the crack appeared first and the rest then followed
I have had a fan snap in half (the bit that flew off slightly denting the bonnet in the process) and also have had a chunk break off a bottom pulley.....the best one was a fan belt that broke, which slashed through a radiator hose and pulled a load of wiring out of the O/S front headlamp!

[kevin s]

I would suggest the bolt came loose then it cracked with the bolt torqued up it shouldn't see any great stess at the back face as it will effectively be a homogeneous part of the crank, lose the clamp force and all the bending load will then pass through the bore and be trying to open it up giving a peak stress exactly where it has cracked.

I'm not big fan of tab washers, they just soften the joint, hence why nobody uses them nowadays, I've used loctite and the correct torque on ours with no problems.

[Tootall]

The engine was professionally-built and has been in the car for over a quarter of a century... there certainly was a lock washer there originally but clearly it was lost in the road, when the balancer flew off... Amazingly, the bolt ended up on the panel below the radiator.

I've sourced a second-hand pulley on eBay - exactly as in that link provided by @philthehill ... do I need to remove the inner-most metal part of the pulley? Presumably on a Mini (which is where I assume it originally came from) it doesn't cause harmonic problems, as it is...

Have removed the front of the car - the woodruff key is still in the crank - looks like it'll be quite tricky to remove/replace it... there's also what seems like a fairly solid washer which will butt up against the end of the pulley's 'shaft'... Presumably that should remain in situ?

Will clean up the 'new' pulley as much as possible and will probably use a new bolt... the engine builders didn't put on a starter dog, as they said the compression ratio would make it pretty hard to turn over on a handle... it's not a racing unit or anything too wild - anyone have a starter dog on their 1275?

[philthehill]

if the woodruff key looks to be ok I would leave well alone.
You need to remove the disc riveted to the back face of the damper pulley. Just drill of the heads of the three rivets and knock the rivets out. Doing this will not up set the balance of the pulley.
The large washer could be the oil thrower plate which is marked by a 'F' on its front face.
A close up photo of the dismantled front of the engine would be helpful.

[Tootall]

if the woodruff key looks to be ok I would leave well alone.
You need to remove the disc riveted to the back face of the damper pulley. Just drill of the heads of the three rivets and knock the rivets out. Doing this will not up set the balance of the pulley.
The large washer could be the oil thrower plate which is marked by a 'F' on its front face.
A close up photo of the dismantled front of the engine would be helpful.

Here are a couple of close-ups of the nose of the crank...

IMG_6296.jpg (3.1 MiB) Viewed 938 times

IMG_6297.jpg (3.52 MiB) Viewed 938 times

Looks likr the washer thingy has been damaged during the pulley's journey off the car... there doesn't seem to be a washer listed on the ESM website but I found this on SC parts's exploded diagram for Minis... an adjusting shim (47) - would that be it?

IMG_6319.jpg (1.55 MiB) Viewed 934 times

Why the need to remove the rearmost part of the pulley/balancer? Does it foul on the water pump?

Also, what's the name of the panel that the radiator mounts to, behind the front panel... mine is cracked and will beed replacement - eventually, if not imminently...

[svenedin]

Part 47 is definitely damaged there and it looks like the threads are damaged too unfortunately

[philthehill]

Firstly you will need to take off the timing chain cover to fully see what the damage is and to expose the 'washer'.
You do need to remove the timing disc on the rear of the damper pulley otherwise it will foul the timing chain cover. Later timing covers for use with the damper and later type ignition have a stepped front face to give clearance for the timing disc. The timing chain cover shown does not appear to be stepped. To remove the timing disc just requires the heads drilling off and the rivets knocking out.
The timing chain cover will need to be removed to replace the timing chain cover oil seal in any case.
Item No: 47 is the shim (various thicknesses) which sits to the rear of the crank timing gear on the nose of the crankshaft and to the rear of the Woodruff key. Those shims are fitted to adjust the alignment of the crank and camshaft gears.
This is the tap that you will need to clean up the threads inside the crankshaft nose.
https://www.ebay.co.uk/itm/363686649697 ... R6SfrJSqYg

[Tootall]

Firstly you will need to take off the timing chain cover to fully see what the damage is and to expose the 'washer'.
You do need to remove the timing disc on the rear of the damper pulley otherwise it will foul the timing chain cover. Later timing covers for use with the damper and later type ignition have a stepped front face to give clearance for the timing disc. The timing chain cover shown does not appear to be stepped. To remove the timing disc just requires the heads drilling off and the rivets knocking out.
The timing chain cover will need to be removed to replace the timing chain cover oil seal in any case.
Item No: 47 is the shim (various thicknesses) which sits to the rear of the crank timing gear on the nose of the crankshaft and to the rear of the Woodruff key. Those shims are fitted to adjust the alignment of the crank and camshaft gears.
This is the tap that you will need to clean up the threads inside the crankshaft nose.
https://www.ebay.co.uk/itm/363686649697 ... R6SfrJSqYg

Thanks for the advice Phil (and everyone else...)

As usual, looks like it's not just a case of 'bolt on the new bit'...

My replacement part is a little rusted, which I can smooth off with some emery paper - but how tight a fit should it be on the nose of the crank? I assume it won't just glide on easily but how much of an 'interference' fit is it? Should I be able to push it on or will it need a press of some kind?

[philthehill]

The damper pulley should fit onto the crankshaft nose with a firm push. At most use a hide faced hammer with gentle taps.
Tips:-
Fit the timing chain cover with just two or three loose bolts, fit the damper pulley so as to centralise the timing chain cover & lip seal, turn the engine over a couple of turns to ensure that it is central, fit and tighten all of the timing chain cover bolts. As well as fitting the lock washer I would use a drop of Loctite on the bolt/starter dog threads. I do not use any means of locking the damper bolt/starter dog other than some Loctite on the threads of the damper retaining bolt/starter dog and I have never had a bolt or starter dog come loose.

WDF engine 9.jpg (66.74 KiB) Viewed 862 times

[Tootall]

Thanks @PhiltheHill...