Fan belt .. yummy :D

Post by **alainmoran** » Sun Aug 16, 2009 5:25 pm

My engine seems to have developed a taste for eating fan belts ... you put them in and it eats them, not quite literally but close.

When I first put the engine together there was quite a bit of corrosion on the pulleys which I've since filed off and made smooth (after it ate the first belt), I then put another on and a few weeks later (maybe 250 miles) it's close to having eaten that one too.

The fan belts go in as normal, however they seem to get thinner and more pointy, meaning I have to adjust the tension again until it completely eats the belt - where I have it maxed out on the adjustment and it's still slipping.

I'm hearing a fine hiss/whine, not quite a squeal but like it's about to let rip with a screech ... I'm not sure what I can do to solve it? ... Am I putting the belts on too tight, or too loose?

Should I have another go at the pulleys, they were mostly free of corrosion after the last go I had at them, but the surface could have been made smoother by using a less agressive file.

Post by **MarkyB** » Sun Aug 16, 2009 5:41 pm

Hiss/whine sounds like too tight.
There is supposed to be play (1/2 inch?)
in the long part.
It shouldn't be "bar tight" not only will it eat belts a taste for bearings will develop too

Post by **alainmoran** » Sun Aug 16, 2009 5:58 pm

Eeek ... thanks ... I figured I was doing something wrong, and yes last time I put it on I did make it pretty tight as I was sick of it slipping :s

Which bearings and how best to check their current state?

Post by **MarkyB** » Sun Aug 16, 2009 6:54 pm

Dynamo and water pump in that order.
Noise and water leaks would be the likely symptoms.
With the fan belt off look for play in the direction that the belt pulls them.
If it was screeching before then think about what load you are putting on it.
Lights, radio, heated screen and fan blower then start the engine is too much to ask.
Start the engine 1st then start adding load to the charging system.

Also, while you have the belt off make sure all the pulleys are in line with a straight edge.

Post by **bmcecosse** » Sun Aug 16, 2009 7:32 pm

Yes - it's essential the pulleys are perfectly lined up - sounds like they are not!

Post by **alainmoran** » Mon Aug 17, 2009 11:54 am

Hmm ... they 'look' like they are in-line however that's only by eye.

You say to check using a straight edge, I have one of these, however I'm unsure how to use it to check the pulley alignment ... to my mind I'd need to be checking all three pulleys against each other & I cant quite see how to do that.

It's quite likely that they are not inline as I replaced the original dynamo on this engine for an alternator.

Post by **bmcecosse** » Mon Aug 17, 2009 12:06 pm

You can 'assume' within small tolerance that the bottom pulley and the water pump will be fine - so look to the water pump/alternator alignment. Very often a thick washer is needed between water pump lug and alternator to make them align. Then slacken the rear bracket to allow it to re-align - and tighten all up.

Post by **rayofleamington** » Mon Aug 17, 2009 4:48 pm

There is supposed to be play (1/2 inch?)

They need to be tighter when using an alternator.
A tight belt often leads to a failed bottom pulley - which can often cause a failed radiator!

Overtensioning shouldn't cause the belt to wear away like that - when it's worn it should reach 'normal' tension and then be ok. Possibly your pulleys are too damaged and/or the alignment with the alternator is wrong.

Use the straight edge off the back face of the water pump pulley to check the alternator lines up properly.

Post by **MarkyB** » Mon Aug 17, 2009 6:01 pm

What alternator did you use?
"thinner and more pointy" suggests it has a different profile pulley to the water pump and bottom pulley.

Post by **alainmoran** » Tue Aug 18, 2009 1:53 am

Teh alternator came off my originally 'spare' engine that was in the car before I put my better quality engine in (which was originally on a dynamo) ... I'm pretty sure that it's the right alternator, but I'll check for a serial when it is light.

From what people are saying, along with the fact I was never entirely sure that I had the alternator lined up right (I took it off and put it back on a few times before I gave up and decided to just give it a go as the light was failing), then I think that the problem is likely to be my alternator alignment.

Post by **Peetee** » Mon Aug 24, 2009 10:55 am

The alternator I fitted wouldn't align properly so I removed the specific rear bracket, used the original one designed for the dynamo and replaced the two securing bolts with a single threaded rod. With a combination of washers and nuts I got the right fore-aft alignment for the belt.