Bongo Fury

Neigh, don't encourage him........................

I'd be amazed, neigh flabergasted, if the rubber belt vee would cause a cast iron pulley to break

Just a thought from a 'non mechanic'. If there was a small crack in the cast iron pulley, and there was a little water egress - could a very cold frost cause the crack to become a break.
ian G

dandywarhol wrote:Neigh, don't encourage him........................

I'd be amazed, neigh flabergasted, if the rubber belt vee would cause a cast iron pulley to break

I think it's the rubber joint that has broken up - the Bongo pulley doesn't seem to be a failsafe one like others I've seen.

Thats how I see it too - it's an iron pulley rubber bonded to a hub which keys to the crankshaft - the secondary vibrations (mainly caused by the pistons travelling further in the 1st half of their stroke than the second half) cause the outer part of the pulley to oscillate and cancel out some of the vibes.
If the bonding fails then the 2 parts seperate
I still don't get the bit about the belt causing problems...........

dandywarhol wrote:Neigh, don't encourage him........................

I'd be amazed, neigh flabergasted, if the rubber belt vee would cause a cast iron pulley to break

I'm amazed you're amazed Dandy

Seriously though, I recall this being stated (and accepted as plausible cause) during a debate about it some time ago. It would be interesting to dig up and re-read the thread in question. So apologies, but I'm only trying to re-state what was said way back then. I must admit, it seemed to me at the time the statement was made, that a mismatched belt / pulley profile could put abnormal stress on pulley faces, though not having seen how the pulley is (over)engineered I couldn't have a view on whether it would cope with the stress. But I would think it prudent whatever the finer points of the argument, to ensure the recommended belts are fitted wouldn't you?

Bloody ell Mike please don't use the 'P' word you will give me nightmares of the son of the Manse.

mikeonb4c wrote:

dandywarhol wrote:Neigh, don't encourage him........................

I'd be amazed, neigh flabergasted, if the rubber belt vee would cause a cast iron pulley to break

I'm amazed you're amazed Dandy

Seriously though, I recall this being stated (and accepted as plausible cause) during a debate about it some time ago. It would be interesting to dig up and re-read the thread in question. So apologies, but I'm only trying to re-state what was said way back then. I must admit, it seemed to me at the time the statement was made, that a mismatched belt / pulley profile could put abnormal stress on pulley faces, though not having seen how the pulley is (over)engineered I couldn't have a view on whether it would cope with the stress. But I would think it prudent whatever the finer points of the argument, to ensure the recommended belts are fitted wouldn't you?

Yep, agreed - when I changed the water pump on mine I found the belts were the wrong profile - all they did was wear faster until the cords were exposed - didn't fracture the pulley

Hi All

I thought I would update every one on this problem and its fix. As you recall some of you did offer a good explanation so:-

The Crankshaft pulley is made in two parts, these parts are bonded together with rubber. Their is a gap between each belt pulley on this unit so all the drive belts(aircon, alternator and power steering) stay apart.

In my case this rubber bonding broke down causing firstly the two parts of the pulley to become loose and moving out of alignment and catching on the engine casing. The smell I reported is due to the belts coming into contact with each other as the alignment on the pulleys is now all over the place.

fix: remove all belts, remove crankshaft pulley( its just held on with a large nut and washer) replace with either a new one £150.00 app or a used one £50.00. The shaft on the pulley is splined so you can only fit one way. Replace all drive belts and tighten. Its impossible for you to do unless you can lift the whole van of the ground to gain access and remove the nut(it needs a great deal of torque- welly to remove it)

So its not the end of the world as we know it but a word of CAUTION, if this happens to you, YOU MUST NOT DRIVE THE VAN as you risk serious damage to the engine casing and also alternator, aircon bearings etc. I hope this may help someone else if they suffer this problem and again thanks to all concerned.

al
(happy man now)

That's fab news - I bet you're mightily relieved?!

But, £150 for a crankshaft pulley?!!! Jeepers...

Glad its fixed. Just to return to the 'wrong belts' issue, I think it was the fact that they could drive the two halves of the pulley apart that was the point made by someone a long time ago. But I'm not going to argue the point as I really don't know!!!

Good write up al...............

Have a look at the pulley (11-371) in the pic Mike - it's a cast iron pulley, the pulley sides don't "open up" where the belts operate, it's the centre part which is keyed to the crankshaft and the "outer" part (the pulley vees) which separate at the rubber bonding. In al's case it sounds like the outer part then became misaligned which allowed the belts to try to "crossover" each other and rub together.
I just cannot see the pulley sides separating on this setup, whereas they could do on a steel alternator pulley...................

http://www.lushprojects.com/bongoparts/ ... R26031.gif

dandywarhol wrote:Good write up al...............

Have a look at the pulley (11-371) in the pic Mike - it's a cast iron pulley, the pulley sides don't "open up" where the belts operate, it's the centre part which is keyed to the crankshaft and the "outer" part (the pulley vees) which separate at the rubber bonding. In al's case it sounds like the outer part then became misaligned which allowed the belts to try to "crossover" each other and rub together.
I just cannot see the pulley sides separating on this setup, whereas they could do on a steel alternator pulley...................

http://www.lushprojects.com/bongoparts/ ... R26031.gif

I'm outa here - only the messenger etc. and not taking Dandy on over mechanicals, with his pedigree. I'm nuts, but I'm not that nuts

mikeonb4c wrote:

dandywarhol wrote:Good write up al...............

Have a look at the pulley (11-371) in the pic Mike - it's a cast iron pulley, the pulley sides don't "open up" where the belts operate, it's the centre part which is keyed to the crankshaft and the "outer" part (the pulley vees) which separate at the rubber bonding. In al's case it sounds like the outer part then became misaligned which allowed the belts to try to "crossover" each other and rub together.
I just cannot see the pulley sides separating on this setup, whereas they could do on a steel alternator pulley...................

http://www.lushprojects.com/bongoparts/ ... R26031.gif

I'm outa here - only the messenger etc. and not taking Dandy on over mechanicals, with his pedigree. I'm nuts, but I'm not that nuts