MGF alternator belt always slips in wet weather.

[bigbadbikercats]

My 'F always makes horrid screeching noises in wet weather (and it's very wet today) and resetting the belt tension (or even replacing the belt) only ever seems to give brief temporary respite. When I look through the right rear wheel arch the crankshaft pulley and the lower run of the belt are pretty much open to the elements and it's got me wondering if I've got a cover or bit of inner wheel arch shielding/trim/whatever missing which is allowing water (and general muck) onto the belt and pulley. Anyone know what it should look like under there and maybe give me a pointer to what (if anything) I should be looking for on eBay or in the breakers?

Car's continuing to behave itself by the way so I'm feeling increasingly comfortable with the idea that it was a failed expansion tank cap rather then the dreaded HGF which caused my big clouds of steam

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JG