Belt Squeal

Hi all

About a month ago my fan belt snapped after several weeks of it squealing. I've recently replaced it but it still squeals. I had a mechanic check that it is tight enough and he seems to think that it is.

It seems to squeal mainly while the engine is cold, and particularly at night when the headlights are on. It squeals for a long time and sometimes the only way to stop it is to turn the headlights off and on again, although sometimes this doesn't work.

While it was squealing this morning I lowered the window and noticed that it was very slow to open.

Could there be a problem with the alternator that would case the belt to squeal?

It could be a number of things.

It could be that the battery is on its way out and the alternator is doing overtime to keep up or some twin cams have crank shaft pulley failure issues that make the belt squeal a bit.

It could be an issue with the alternator.

A bit more investigation is required I think.

Kirkynut

Thanks for the reply and suggestions - at least I have somewhere to start now

Check the crankshaft pulley although the damage is not always obvious to the eye without getting to both sides of it. I am assuming from earlier comments that it is the m13a dual cam motor by the way.

Hi mickt

Thanks for oyur reply. Yes it's the DOHC. The crankshaft pulley is a lot cheaper than an alternator so will check that if the battery tests out okay. Thanks again

Just had a closer look and I noticed black residue on the front of the alternator (see pic). Could it be that the alternator pulley is seizing and damaging the belt?

2013gary wrote: Just had a closer look and I noticed black residue on the front of the alternator (see pic). Could it be that the alternator pulley is seizing and damaging the belt?

Sure looks like it. the bearings in the alternator could be broken.
You can try to onhook or loosen the belt and spin the alternator pulley with your fingers. should be easy to turn around with little or no resistance.

I doubt that any electric resistance from charging can do that.

You get that as the belt is starting to disintegrate because it is running out of kilter. When my daughters car ran the belt I just assumed that the belt had worn due old age. After cleaning and checking everything whilst replacing it (I took the radiator out as I find it does not take that much longer and access is a lot better as it is easy to damage a radiator) and after not too long it ran another. I changed the pulley this time as well as two new belts, and although there was no obvious damage to the pulley the fault has been cured. So take the belt off and spin the alternator as well as pulling the shaft checking for rotational and end float play. My bet is the pulley. There is a wright up for how to do it on the forum ,the biggest challenge is undoing the pulley nut. I made up the spanner mentioned but a good impact driver or flicking the starter are other options.

I have the identical problem as your self, I bought the car a year ago and had belt squeal when I bought it, alternator belt broke not long after and I replaced both belts, squealing has returned and I've just bought another pair of belts, I do very few miles in the jimny, I've only done 2500 in the year of ownership so the belts have less than that on them. Mot tomorrow evening so I'll check out the crankshaft pulley after that.

Thanks for the replies. I do now think it's the pulley on the alternator. As yakuza said that this should spin freely, and when I changed the belt I remember there being some resistance but thought nothing of it at the time. When I changed the belt it was such a faff (I broke the crankshaft sensor while prying the alternator along its bracket), that I think I will just get a trusted mechanic to do it this time. In which case I might as well get him to change the crankshaft pulley at the same time.

weecorey sounds like a pulley could be seizing somewhere (if you're sure that there is enough tension in the belt). On both occasions my squeal was accompanied with a slight smell of burning rubber if that helps.

I've had my Jimny over 3 years now and it has always squealed a little bit - particularly when it's been very wet, which I assumed was normal. It was only when I had to start turning headlights on and off to stop the squeal that I thought it might be a bit more of a serious problem!

Hey guys, I’m getting the same problem annoyingly. One of the belts on my jimny has began to squeal on start up and predominately at night when the lights come on. I’ve put a multi meter to the battery and it’s reading below 12v which is stupidly low - so assuming it’s the alternator working hard to charge it up, because the noise soon stops after a minute of driving.

The belt was replaced about 2 months ago by a garage and they seem tight enough to me. Would you suggest it’s the battery that needs replacing ?