Technical leak from thermostat

[TONY55S]

Hi All,
I fitted a new thermostat to my fiat punto mk2 b.
i just used the gasket that came with it,and tightened it up.
The problem i now see is a very small leak of coolant from the thermostat.
My question is if i buy the silicon do i put a small amount on BOTH sides of the gasket?
any help appreciated/

 

[judderbar]

the gasket is a bad idea. if you perfectly apply silicon on both sides of the gasket the porous paper gasket probably leaks water. i used the gasket first time and it leaked. never leaked without the gasket. Check however it is not leaking from the hose. i needed to clean up the inside of my hose and get all the crud off before it would seal properly.

 

[Pugglt Auld Jock]

Same hose problem with mine. Corroded bits of the old thermostat housing were sticking to the inside of the hose. Easy enough to clean out with an old knife. The last one of these I did was the Original Birth one sold by S4p and it comes with a gasket. I put a light skim of silicon gasket cement on both sides of the gasket - you don't need much, most of it gets squeezed out as you tighten it and, if you use too much some may break off and go round the system to block up radiator or heater matrix internals. That was at least 2 years ago and no signs of any leaks yet.

My favourite for many years has been Loctite Si 5980: https://www.henkel-adhesives.com/ng/en/product/gasketing-sealants/loctite_si_5980.html I use it on sumps, water pumps, thermostat housings, Cam covers and many other similar situations. It comes in good old tubes as well as the fancy dispenser shown in the ad and can be bought in most factors, Halfords, etc. Just make sure you properly clean and degrease the surfaces you want it to seal to.