Fan belt has come off

wrote:

Pheaton
Crank pully failure is quite common on the M series engine 
These have a bonded rubber that deteriorate allowing the pully to wobble 
This can make belts jump off

I wasn't aware of that, but unless it's happening on more than 1 occasion you wouldn't do it that way surely?

Personally if mine chucked a belt 1 time the crank pully would be the first thing I changed 
 

Two possibilities.

1) the alternator.  They rust inside (especially if a previous owner has been driving through water- I suspect mine had...) and the rust flakes drop into the works. When you first start up the alternator runs full field, and the magnetism attracts the flakes into a lump that seizes the alternator. When you turn the ignition off, you can move the alternator by hand, redistributing the rust and it will be fine for a couple of days before doing it again.

This doesn't fling the belt off, it just tries to set fire to it (the alternator pulley will burn your fingers), but if the crank pulley is starting to go it might flip off.

2) the crank pulley.  This is a very poor design, the alternator grooves are in fresh air, and the fan belt tension acts to rip the rim of the pulley off the hub, it is only held on by the bond between the rubber and the hub.  Grab the outer pulley and try and rip it off the car, if there is any movement, change it.

You might have both problems at the same time!


I struggled on & off for 3 days to get the crank bolt undone on mine, I made a tool to screw into the holes on the pulley, and had the 6 foot scaffold pole to the bolt, I was sure the engine mountings would break. I even bought the most extreme powered 1/2" drive windy gun that Machine Mart had and rattled it until I was sure I'd get that vibration white finger thing.

Eventually, I got a slitting saw to it and cut the integral flange off the bolt in pieces, and it undid with my fingers.

Here is a section through the pulley showing how the poor design makes it literally fall apart when you are going along.

 

And some pics of the changing process

 

 

     

 

Lots of useful info there @facade

I did wonder about the alternator, but the fact I could turn it after the belt popped off made me think it was okay ... after what you've said maybe not.
The fact the power steering belt is coming off too though makes me think crank pulley.
I do have a new pulley, tensioner and radiator on the way. My rad is very old and I don't think it will survive the removal and refitting.
Looks like I might have to add a pulley bolt to my shopping list.
Cheers. I will report back when I get time to tackle it.

Facade, your crank bolt was well and truly stuck and a bit extreme to have to cut the pullt off.

I made a similar jig to yours and a 1m long breaker bar with six sided impact socket got my bolt out, with a bit of help from a friend. It never occured to me to buy a new bolt, but after seeing yours I wish I had done.

I hope the pully isn't a bi-annual service item, never had to do one on a car before.

Robin

I suspect a previous owner had been driving through water- just look how corroded the pulley was. The flange on the bolt had rusted solid to the pulley, once the flange was off it lost its tension and there was nothing holding it so I undid it with my fingers.


Checking the date on the picture it was 2016, my Jimny was a 2000 plate, so it lasted 16 years. (I can vouch for 6 of them, I got it in 2010).


It took me 3 days to think to cut the flange off and just get a new bolt, I should have done it as soon as the scaffold pole didn't work