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Crank pulley bolt problem

Posted: Sun Oct 07, 2018 11:26 am
by Doggy
Attempting a cambelt change, I've undone the crank pulley bolt, turned it 3 or 4 revolutions but it feels like the thread's picked up. It won't re-tighten without excessive force either. Letting some WD40 soak in while I ponder.
Feels like it will snap before it comes out, so now I have a dilema - I could:

1. Carry on regardless, but if it snaps or strips the thread so it won't go back in that's probably game over for a car I rather like.

2. Attempt to re-tighten it, outcome probably as above.

3. Try to slot some washers to fill the gap twixt bolt head and the pulley so it only needs say one turn to lock the pulley in place. Might work as a short term fix, but what then?

Guess I don't absolutely need to do the timing belt this minute, but it's 94k / 3 years since I did it last and I'm hoping to prove/eliminate the water pump as the cause of my minor fluid loss.

Any suggestions?

Re: Crank pulley bolt problem

Posted: Sun Oct 07, 2018 12:43 pm
by steve_earwig
Lord knows! :shock: I reckon jasper's your best bet. It's another one of them "whatever I do will be wrong" situations but, without resolving it one way or t'other, you'll be driving a car that could go pop! at any moment. I reckon I'd try rocking the bolt back and forth, try and work it out bit by bit and hope it's not damaged the crank too much.

Re: Crank pulley bolt problem

Posted: Sun Oct 07, 2018 1:07 pm
by Doggy
steve_earwig wrote:
Sun Oct 07, 2018 12:43 pm
without resolving it one way or t'other, you'll be driving a car that could go pop! at any moment
Worse than that, the crank pulley's loose so it ain't a goin nowhere.

---or wasn't. I took the semi cowardly way out and tightened it back up v e r y c a r e f u l l y.
The last turn or so was almost free, so I naturally tried undoing it again and again and then resisted adding to 40-odd years of not quite learning when to give up. So it's done up for now and therefore derivable, while I work on Plan B.

Re: Crank pulley bolt problem

Posted: Sun Oct 07, 2018 7:16 pm
by caprixpack
Balls to the wall, get a windy gun on it :twisted:

Re: Crank pulley bolt problem

Posted: Sun Oct 07, 2018 9:37 pm
by grasmere59
In my experience once a thread has picked up it's game over,it's a weird phenomena no amount of force will undo it but it will do up again,not really a feesable option but the only way i can see to save the threads in the crank is to drill the bolt out.

Re: Crank pulley bolt problem

Posted: Sun Oct 07, 2018 10:15 pm
by PeterN
Put a socket on it with a long bar that will reach the ground at the front of the engine and just 'blip' the starter, that usually gets them off.

Peter

Re: Crank pulley bolt problem

Posted: Sun Oct 07, 2018 11:14 pm
by Doggy
Don't fancy my chances of drilling the bolt accurately enough to save the thread in the crank - not the easiest place to ensure you get it dead centre and the drill constantly on the right axis, but may have to try it if all else fails.

Impact wrench may be an option, half the problem is the inability to prevent the engine turning with a wheel off. I shall think about an effective way of locking it.

Least it's up and running again while I ponder my next move.

Re: Crank pulley bolt problem

Posted: Mon Oct 08, 2018 10:09 pm
by dirtydirtydiesel
Eric,
When it was last done, did it have a new bolt installed ?
The reason I ask is I've done mine twice now each time with a new bolt from the main steelers.
These bolts come with locking paste already on them, this can make them feel as though there picking up
as you wind them out.
I have always done it John's way with the breaker bar on the floor & wind it out on the starter,
The last time I had already disconnected the ecu, so just kept it on the starter until if fell out :supafrisk:

As long as you don't, didn't re-use the old pulley bolt you should be golden 8)

Re: Crank pulley bolt problem

Posted: Mon Oct 08, 2018 11:15 pm
by Doggy
New bolt fitted along with timing belt kit last time, 8)

..but then I changed the crank pulley last year and re-used the same one, since only normally get a new one with a belt kit. :oops:
came out easily last time, went back in easily and was torqued up correctly.

Didn't risk forcing it yesterday, I was having to use the breaker bar to turn it so the more it unscrewed the greater the sideways force/risk of snapping it. Going to have another go probably with a battery impact wrench so I can ease it back and forth without any load in the wrong axis.
Also plan to gather a set of cobalt drills, taps etc
ServiceBox describes the Crankshaft Pulley Screw as M14x150-70, which I suspect means a 70mm long M14x1.5 part-threaded screw, (M14 fine is 1.5mm pitch). A bit like this:
Image

If it does shear off, I'm hoping it might leave at least a little thread protruding from the crank. This would allow me to fit a s/s capped nut with a pre-drilled pilot hole spot-on centre, so even I can start drilling in the right place for once. We'll see.

Re: Crank pulley bolt problem

Posted: Tue Oct 09, 2018 10:15 am
by PeterN
If it should break off, even if its flush you could weld an nut onto the stub through the hole, not only will that give you something to grip but the heating will expand the hole more than the bolt which also helps.

Peter

Re: Crank pulley bolt problem

Posted: Thu Oct 11, 2018 4:13 pm
by jasper5
I don't know if you have already sorted this problem, I've been away so didn't see the post.

My solution to this problem is this...
If you have got the bolt moving carry on with the WD40 into the threads and moving the bolt in and out gradually.
I usually use the starter motor trick but that might not be a good idea in the circumstances, but if you are brave enough....

If the bolt was similar to the one in the pic with thread lock on it's possible that it is jamming on the thread lock (99% of the time that is the case)...applying heat to the bolt would soften the thread lock then hitting the end of the bolt will free it up.
To lock the engine there are crank locking tools which slide into the teeth of the flywheel and then bolt into a bolt hole around the gearbox casing which is exposed where a tin plate might be....they aren't expensive...in fact the Peugeot locking kit has one of these in it.

If all else fails and the bolt breaks there is a foolproof method of drilling straight into the centre of the bolt...it requires a bit of engineering but it works....

Make up a round piece of metal that fits snugly into the bolt hole with a small diameter hole for a pilot then drill a pilot hole.
Gradually increase the hole with bigger drill bits until you get to the size of the bolt or intervene with an easy out somewhere in the process.
Hopefully you can get a tap in and clean up the thread.
If you can get hold of some left handed drill bits then the process could be easier if you think about it.

Re: Crank pulley bolt problem

Posted: Thu Oct 11, 2018 10:04 pm
by Doggy
Not resolved as yet, waiting for a window when I can afford to have it off the road for a few days if necessary. There's no compelling rush to get it done, I'm hoping to confirm or eliminate the water pump as the cause of the minor coolant loss I've had on & off for a few months.

That's a good suggestion for getting the drill on centre, I may well try that. I'll look for a crank locking gubbins too.
Many thanks for your help, always appreciated.