Hi All,

Right, I just replaced my thermostat, new O-Ring with plumbers grease, tightened up the bolts, bled the system - as soon as the thermostat opens it starts leaking from the joint where the thermostat housing meets the engine body. I've removed the housing again to check I haven't done any damage or cracked it - everything seems fine - in fact I took the housing off three times to check the correct placement of the o-ring and carefully and evenly tightened the bolts up each time - it's still leaking.

Any ideas anyone? This has been driving me absolutely mad today.

Cheers guys.

sounds like u have a fine crack

Whats car is this on ???

its a 2001 golf 1.6 (mk4). I had a very good look at the housing - I can't see any cracks at all but always a chance I overtightened the bolts on my first attempt at reattaching I suppose.

Thanks Lee - I actually used Loctite Blue Gasket maker and it's done the trick a treat - no more leaks. Just noticed a slight smell of petrol in cabin (when the air conditioning is on) now I can actually drive it again - will have a proper look under the bonnet at the weekend for splits / loose connections.

I have seen this many years ago on a mates Gemini when he had replaced the bolts, the problem was that the bolts where a fraction longer aNd the bolts bottomed out just before the faces sealed really hard to pick.
Gasket maker is great stuff to use.

common problem ..replace the fitting they are cheap ......