Toyota Yaris Verso screeching in wet weather

[Riverbird]

Does anyone have any idea what causes an awful screeching noise, strangely in wet weather only, which sounds like a very badly slipping fan belt but worse ? It is a year 2000 Yaris Verso and has had two mechanics look, and both say belt was fine (but changed belt anyway) and they are scratching their heads. Difficult when it won't make the noise to order. At some stage, usually within 15 mins of starting the noise it wears off on its own, but it really is very noisy and causes odd looks. If anyone else has had the same problem would appreciate advice if they have solved it. Thanks very much.

[alan333]

Your symptoms would normally suggest the alternator belt, but obviously yours shouldn't be, since it's been changed.  The alternator belt works it's hardest just after starting the car, since it has to generate power to replace the power it just used when starting the car.  Hence you would normally hear it worst for the first while after starting, and worse still if you have lots of electrics/lights/rear window demister/heater etc on.  If yours has these symptoms, including being worse with all electrics on, then it definitely points to a problem with the belt slipping.  However it could be slipping due to a partially seized pulley, rather than simply being slack.

[Cyker]

Had the same thing in my diesel Yaris; Changed the aux belt, tightened it, sprayed it with WD40, nothing worked long term - Always the horrible shrieking until the car warmed up.

However, it turns out the Yaris Mk1 has hydraulic power steering and there is *another* belt in there for that which, on mine at least, was the one causing the death-cat-squeal.

I bought the replacement from Toyota; Was pretty cheap IIRC.

[Riverbird]

Thank you very much for both suggestions. I will give them a try and see what happens. Only difference is my screech starts when I drive through  puddles or in the wet, not when I first start out. So fingers crossed it works or I will need to buy ear plugs!