Thermostat gasket, sealant or no sealant

[djheath]

Hello,
Just a quick question.
1999 406 1.8 16v XU7JP4 engine.

I have a leak from the top of the thermostat housing, between engine and thermostat housing. When I changed the coolant a few weeks ago, I took the housing off, cleaned the faces and used the blue hylomer sealant on both faces. It has since started leaking again in the same place. Since doing that job, I have discovered Peugeot's Service box and found that there is a gasket available for this job, which I have bought.

My question is, should I use some of the blue hylomer sealant on the gasket as well, or should the Peugeot gasket be enough to seal the thermostat housing? I dont want to waste even more fresh coolant if it starts to leak again!

Thanks!

[Welly]

This leak on your engine is common and affects a component underneath to do with the idle control or summut

Anyway - the new gasket should be an O ring unless I'm mistaken and the idea is to just use the O ring on very clean mating faces and that's that.

This could all be bollox though not having done one myself but I'm sticking my neck out and going for an O ring (like other cars I've had).

See what some others say............

[djheath]

Cheers for the reply. I have just read the FAQ bit on the crank sensor and how its affected by the leak which has concerned me and made me want to get it perfectly correct.

The o-ring bit I have also, which seals the coolant pipe to the right angled bend on the thermostat, but its the rubber/cork gasket between then housing engine block.
See if this works:
Part 5 on here:


I reckon you're correct that you don't need any sealant, but I just want to make sure.
Thanks again.

[Jimmy]

I always use sealant with these things, I get best results when i apply the sealant, and then tighten the bolts loosely, give it an hour to set then tighten them up again, what i find is if you tighten it up full you squeeze the stuff out, sometime leaveing small gaps, when you wait for it to set a little it turns into a rubbery substance, when pressure is applied it stays put and compreses making a good seal. I do the same with water pipes aswel. I also put a very small amount on the neck of the sump plug.

[djheath]

Excellent advice,

Thank you so much.