When I start my Nissan Primera 2.0 petrol there's a screeching noise which sounds like it's coming from the alternator area It disappears after about 5 minutes and there are no obvious problems - anyone an idea what this is?
An easy check. Open the bonnet, start the car, then spray the alternator belt with a little water. If the screech stops, the belt is slipping. Either tighten or replace the belt. If the screech remains, chances are that it's a bearing problem. Aternator, pump, WHY. Mike.
I've seen that suggested quite seriously. Not a good idea IMO as WD40 remains on the belt, and has slight lubricating properties, so if it turns out the belt is not slipping, you're left with a more slippery belt.
OTH using water is just as effective at diagnosing whether a belt is slipping or not, with the advantage that it has no harmful effect on the belt at all. Usually within minutes the noise comes back, so if the belt is OK it can be tightened without the problem of cleaning WD40 off the belt, or overtightening to compensate for it's effect. Mike.
Or even better, spray with "belt spray" which does not need cleaning off and may even stop a very mild squeak as it makes the belt a bit stickier and conditions the rubber.
DO NOT put WD40 anywhere near an alternator. Are you a complete fool or do you never read labels, or know the first thing about cars. Incase you don't know, WD40 strips the varnish from the windings in the alternator and also eats into rubber. So what do you think will happen?
I have an aerosol of that stuff somewhere in the toolroom at work, but using water is still more convenient. At least I know where to find it :-) Mike.
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I know it's not relevant in this case, but sometimes serpentine belts develop a sort of squishing swishy sound which can be sodding annoying. A very light spray of WD40 or equivalent on the /back/ of the belt (which runs on various idlers etc.) can be very effecting and last for tens of thousands of miles.
As a long time Primera owner, I bet it's the steering pump belt squeaking although it could be the alternator belt. The belts rarely slip at all, what makes them squeak is that the rubber on the sides of the belt has hardened, and as the belt continuously sits into the pulley edges it rubs, making a noise. A very fine wipe of silicone grease along just the edges of the belt is an instant fix. The only belt dressing I ever sprayed on was a disaster, making the noise a 100 times worse.
It was the front belt driving the altenator. My local garage put some special (silicone?) grease on and it disappeared for now Not sure how long belts last this is from 1998 but only 44k miles so wouldn't expect it to be going yet
It's not just the mileage, they deteriorate due to heat/cold, mechanical stresses and environmental contamination. If it's the original belt it's 8 years old and bound to have deteriorated to some degree. These are consumable items, they have a finite life and 8 years is pretty good going.
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