When I start my car there is a terrible screeching noise coming from the fan belt area. I recently changed two belts but the noise persists. There is no noise when I start the car but when I move from 'park' into reverse(or 'drive') the noise is heard. It only lasts for about 30 seconds - when I am off and running it stops.

Does anyone have any idea what it could be? My local mechanic doesn't now and it's difficult as when I drive there the noise has gone. If I leave the car for a few hours it happens, although I noticed that when leaving it in the sun yesterday for 6 hours there was no sound when started.

If it's not the belts slipping (are you sure?), I'd look to the water pump or alternator bearings.

If it's not the belts slipping (are you sure?), I'd look to the water pump or alternator bearings.

Thanks Crossy.

No, not sure. Any idea why it only lasts for about 30 seconds?

If it's not the belts slipping (are you sure?), I'd look to the water pump or alternator bearings.

Thanks Crossy.

No, not sure. Any idea why it only lasts for about 30 seconds?

It always seems that way, not really sure why but I reckon Transam is spot on.

Check your belt tensions (1/2" of play on the longest run is a good check) don't over-tension.

Most newer cars have automatic belt tensioners though so no adjustment to be had, so it depends on which belt it is? Unless your car is a uni-belt system, if not a unibelt system try shutting off your A/C before you start as they will squeal on start up being cold belts and under load from the compressor until the belt is warmed as mentioned, if the squeal goes away the answer is obvious. You say you replaced 2 belts already? Either they were not the right belts or the tensioner is loosing it's tension and it contains one of the pulleys being spoken about.

Did you replace the original belt for the same reason? or just regular maintenance?

Don't think it's a bearing at this point as a bearing would make more noise the harder it's driven and more stress load it is under which is while it is operating at higher RPM's and usually once any bearing begins to make noise it is all down hill from there and makes noise all the time not intermittently, though I'm certain someone will come on and comment otherwise about this rare time when they had this happen..

Actually the answer is not as obvious as I stated earlier, if it does squeal on start up and with the A/C off on start up it could be the bearing in the tensioner going sour as well and not the belts at all, that bearing might quiet down once warm in the initial stages of failure and worked in but it is obviously the beginning of the end for it if that's the case, if it is stiff on start up as in slightly frozen it might also cause the belt to slip around it and squeal until it breaks lose and begins spinning again or it might be just resisting rotation on start up and much slower then the engine speed also causing it to slip and squeal.

Bottom line what make, model and year is the car? Mono-belt system or multi-belt system?

Your battery is on its last legs or your auto trans is very low on oil,torque converters will scream untill they have enough oil to supply the system,

It's the auto transmission, they need frequent fluid change !!!!!!!!!!!!!!!!!