Coolant Thermostat Seals

[cussypat 0]

Hi there

 

I am Annie and a new user and finding my way around this website!!!

 

I have a 1990 205 GTi 1.9 which I brought from a friend 3 years back now... was properly maintained since new but sadly I have let the side down slightly as not as much knowledge as I would like to maintain it properly!

 

Recently the pug (Pixi !!) has been getting slightly hotter than usual... almost boiling point so as a start point I decided to change the thermostat.

 

We removed water thermostat housing to replace the thermostat and then subsequently removed the thermostat... the old stat came out with a little encouragement and there was a rubber washer seal left in place. The new thermostat comes with a new rubber washer seal so we removed the old one, cleaned in and around the areas where the housing meets the cylinder head, placed new rubber washer in the correct position against the head, installed the new thermostat and then reinstated the housing. Tightened up the bolts and refilled the system, however there is coolant leaking from around the area where the housing bolts against the head. Am I missing something i.e. a jointing compound paste, a gasket or a second rubber washer?????

 

Given that the original came out with only the one rubber washer, what do you think I need to do???

 

Your help MUCH appreciated.

 

Anne x

[Anthony 1,003]

Did you remove the whole thermostat housing from the side of the head, or just the thermostat takeoff for the top hose?

 

If it's the former, then you need to seal the housing to the head - either use a gasket or a quality RTV type sealant.

 

If it's the later, make sure you have the correct seals (there's two types - earlier cars use a flat washer either side of the stat, whereas late cars use a single large seal that the thermostat sits inside, and you can't mix them!) and perhaps use a light smear of sealant, although it really shouldn't be needed.

[cussypat 0]

Thanks so much for your reply Anthony.

 

We removed just the thermostat takeoff for the top hose. The new thermostat comes with three rubber washers one of which is clearly not designed for this housing and the second one (which leaked) is exactly the same as the old one I removed and the third one is a washer which can be fitted around the permeter of the thermostat plate so that when it is fitted it has a seal on both sides which is essentially what it needs, however because the thickness of the rubber adds 4mm to the diameter of the thermostat plate it then doesn't fit back into its housing!!

 

I have taken a photograph of the empty housing and then with the thermostat and rubber seal.. but cannot work out how to upload them on here!!!

 

Anne

 

Still cannot understand how a single rubber washer in the housing and then the thermostat and then refit the cover can create a seal.

[S@m 156]

There should be a flat rubber seal on each side of the thermostat. But i usually use a little smear of sealant around edges of the plastic housing before refitting it since i have had them leak without it in the past. Also make sure the surfaces are cleaned back to smooth prior to fitting.

 

Sam

[Anthony 1,003]

There's two seals required on the earlier style housings like you have, one either side of the 'stat, but (as you've discovered) the kits often only come with one.

 

Whilst you can sometimes get away with reusing the old one for the 2nd seal, it's bad practice to in my opinion, and often it doesn't work very well either and results in a leak. Two new seals (not expensive from Peugeot) and a thin smear of RTV and all will be well.