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My mk3 has been overheating occasionally recently, which I reckon was a sticking thermostat (bottom radiator hose wasn't heating up). So, I thought I'd stick a new one in, flush out the system and treat it to some new coolant. Then I decided I might as well change the water pump, and timing belt while I was at it.

The problem is, now that I've done all that, the new thermostat doesn't seem to be opening either! Am I missing something here, I don't see what else it could be.

To add insult to injury, the new water pump sounds awful. My old one had just a faint rattle now and then. This new one is ten times worse. Do water pumps need time to bed in? If I drive it a bit will it quiten up, or have I just part-exchanged my fairly serviceable pump for a knackered one?

All in all, a very frustrating day. I even splashed out on genuine VAG parts, thinking everything would slot together nicely and work. I guess it's never that simple.

#Sigh#

Is the replacement water pump a genuine item?

Yeah, it was a VAG part. I put in a new pump and that's sorted now.

I'm still having thermostat problems though. At the moment, its running fine with no thermostat, but when I fit one, it overheats. Out of the car, the thermostats (the new one and the old one) both seem to open ok. I can't see any reson for it.

Might try getting a new housing from a scrapper and see if that helps, I'm running out of things to check.