Slight coolant leak. Near the thermostat?

[rippedoffagain]

I have a very slight coolant leak. The fat coolant hose goes to the engine, and secures to a piece of engine that in turn is bolted to the engine block with 3 bolts (I think). Coolant is leaking from between the engine and the metal bit that the rubber hose clamps too.

Am I right in thinking that that's where the thermostat lives? And if so, am I right in thinking that to fix this I need a new gasket for the thermostat housing? and while I'm in there I might as well replace the thermostat as a precautionary measure?

[baggy798]

Yes, that's the thermostat housing. A new thermostat comes with a seal.

Carefully clean up the mating surfaces with a brillo pad or wet and dry. You shouldn't need to use any sealant.

Genuine part number:
273459 - Thermostat (87c) - £17.04

[Forrest]

And if the 10mm nuts are too tight to shift try applying penetrating oil once a day for about a week and then use a quality spanner or socket that grips the flats of the nuts. These round off very easily if someone has overtightened them in the past.

When reassembling, there is no need to over-torque the nuts. A good seal can be achieved at little more than finger tight. I just nip mine down enough to compress the gasket slightly and so they don't shake loose.

[DrivingOnTheSofa]

Just my two pence worth - I replaced my thermostat recently and did the bolts up without too much torque, as described in Robert DIY youtube video, and it unfortunately leaked. I took it apart and looked at the mating surfaces. They seemed to have a baked on pale residue on them, so I cleaned both sides with a little glass paper and tightened it together more enthusiastically, which seemed to cure it.

I'm beginning to wonder if the gunk on there was some old gasket seal and whether that is what Volvo garages where told to do, as it had only Volvo stamps in the book when I bought it.