Major Problem With Crankshaft Pulley

Hi , a fortnight ago whilst on holiday somehow i lost the main crankshaft pulley bolt ???????????, which as you can imagine caused pulley to wobble about and also affect power steering and alternator.
After many phone calls was able to find a garage that refurbs landies etc. He replaced the bolt , added lock thread and torqued it up. All was well until now. I went to use it for work today drove about half a mile and then there was an almighty noise from under bonnet, stopped had a look and once again pulley all lose, bolt gone !!!!!!!!!!!!!!!!. I used last monday with no probs, use it today nackered.
Can someone tell me what the cause is or what the problem is.
Thanks

Only thing I can think of is that your crank is bent or main bearings knackered so it's shaking the bolt loose. I'd have thought you'd have noticed other symptoms though.

HI, I have not had any other problems. My landy has been running as sweet as a nut .

crankshaft pulley is cracked through the keyway, the key will also be worn thin and not fitting the keyway, enabling the pulley to move about, replace asap or you will find yourself with a worn crank and new pulley will come loose on it, it might be best to fit new parts with loctite compound.

if it's a 200tdi the only real fix is new crank and woodruff key as it will be shagged, any other repair won't work (been there)

peters877 said:

Hi , a fortnight ago whilst on holiday somehow i lost the main crankshaft pulley bolt ???????????, which as you can imagine caused pulley to wobble about and also affect power steering and alternator.
After many phone calls was able to find a garage that refurbs landies etc. He replaced the bolt , added lock thread and torqued it up. All was well until now. I went to use it for work today drove about half a mile and then there was an almighty noise from under bonnet, stopped had a look and once again pulley all lose, bolt gone !!!!!!!!!!!!!!!!. I used last monday with no probs, use it today nackered.
Can someone tell me what the cause is or what the problem is.
Thanks

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grab the crank pulley with the bolt off and see if you can rotate it back and forwards, if you can then take it off and look at the slot in it, the woodruff key "the little metal bit that sits in the crank", asuming its there that is and not lost, sits in there and holds the pulley still.

The key only sits in part of the groove so you should be able to see if that part is worn by comparing it to the good bit, normally when it gets worn it allows the crank pulley to rotate back and forwards slackening off the bolt and the pulley will never stay tight.

The key is made of softer stuff than the crank and pulley so it should be the key that has worn or snapped off at the pulley end. You need to be careful here because this key also keeps the pulley behind driving the chain for the timing in place and if the pulley is slack chances are that it will fook up the timing.

If the pulley is worn get another one and a new key, if the crank is worn then grind it out to a size up and fit a bigger key, filling out both the pulley slots, a dremmel will just about do the crank for you, I have used small grinders.

To remove the key get a small centre punch and catch the front edge of it trying to rock it upwards, not sure if it will come out with the timing gear on tho on that engine, might be able to move it and grab it with a pair of vice grips.