Squeeky Aux Belt

A few weeks ago i found a leak on the TD4, it was coming from the radiator hose that goes to the block just under the intake manifold, i need a new gasket, so that now sorted.

But water did run down onto the belt and it became squeeky, since the leak has been fixed it doesnt squeek as much, but still noticable.

So i sprayed a bit of WD40 between the pully and engine block and the noise disapeared instantly, however it came back after about a day.

Why could this be, could the coolant leak of damaged something? the squeek is coming from the pully that is nearest to the thermostat (which is strangley close may i note).
could i get a bit of grease on a toothbrush and lube it up a bit or is it fecked?

Its the rubber belt squeaking as it enters/leaves the turning pulley.

WD40 or anything that is oily or greasy will just damage the already aged belt

You need to use a dry lubricant that will not degrade the belts.

I have used white blackboard chalk with success in the past, but the only sure 100% cure is a new set of belts.

Cheers, S.

so it is a water pump problem............

Or the auxiliary drive belt tensioner or idler is on the way out. If it's this you might see iron fillings around.

dont see any of that, it started just as i had a coolant leak, so obviously the leak has damaged something.