Scirocco Register

My 1990 GTII has decided to obverheat intermittently. I thought at first this was down to a loose drive belt, I tightened it up and ran the car on the drive for half an hour and everything was fine; the temp gauge moved to its normal position of about 1/3 and stayed there rock solid. But now it's playing up again and I wondered what the first thing to check might be? The radiator fan seems to be kicking in when it should, so perhaps it's the water pum and/or thermostat?

All advice gratefully received (and if it is likely to bethe water pump that needs relacing, which of the ones from GSF do I need?)

Many thanks for reading this,

Mine started doing this, all i did to solve it was give the cooling system a good flush through. You wouldnt believe the amount of crap that was flinging around my engine! Check your expansion tank see if theres any 'gunk' in there... mine had a 3/4mm built up at the bottom of it.

cooling system flush as already stated, and probably worth chucking a new 'stat in while you're there. don't forget to fill it with proper coolant, not just water!

Thanks for the advice, guys. Sounds like it's a flush nd a new stat for now; the water pump can be Plan B! Incidentally, I was reading on another thread on a similar subject that some people recommend chucking a handful of Daz or similar in for a few days prior to doing the flush. Never heard of this before...is someone indulging in a bit of chain yanking here, or does it actually help with removing the gunge?

No chain yanking...

Washing powder also works well mixed with washing up liquid if you haven't got any swarfega (but obviously be aware that you may well burn your skin off your hands if you have sensitive skin... try it on a small patch for 24 hours first (like behind your ear ;))