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Thermostat housing; sealant or no sealant?

752 views 8 replies 4 participants last post by  Mondygeek 
#1 ·
On my '02 Focus I've had to remove the thermostat housing that's hidden behind the alternator. I noticed that on removal, apart from the small rubber gasket that fits in the slot, there is no sealant on the mating faces where it touches the engine block. Is this correct, and the housing bolts straight to the block 'dry'?
 
#3 ·
When I fitted the housing back on the block it leaked like a sieve from the right hand side. Mine thermostat housing is on the front of the block on the right hand side behind the alternator. When I was filling up with coolant it was literally pouring out. Removed and refitted it, same. Refitted without sealant and it seems to be ok. Maybe I over tightened it. But until I run it up to temp I won't know for sure?
 
#6 ·
As I understand it, the housing has two connectors, one is sealed by the rubber gasket that fits around the thermostat, and the other is sealed by the 'rubber band' type gasket that fits into a slot in the heater side. When the housing is bolted tight tight, those two gaskets that provide a water tight seal. If either of them becomes compromised then any sealant is not going to help very much anyway?
 
#7 ·
I've fitted one of these twice and what a pain in the arse they are too. The first one I fitted twice because as mentioned it still leaked some so ended fitted a new rubber seal but when I fitted it, I put a little bit of sealant on the thermostat housing under the seal to hold it in place whilst locating and 2 years down the line it still hasn't leaked. For how cheap a seal is to buy it well worth just replacing it and only doing the job once. I also removed the alternator just for ease
 
#8 ·
I've fitted one of these twice and what a pain in the arse they are too. The first one I fitted twice because as mentioned it still leaked some so ended fitted a new rubber seal but when I fitted it, I put a little bit of sealant on the thermostat housing under the seal to hold it in place whilst locating and 2 years down the line it still hasn't leaked. For how cheap a seal is to buy it well worth just replacing it and only doing the job once. I also removed the alternator just for ease
My thermostat housing had some crusty white evidence of a leak when I first removed it. I also made a point of checking it wasn't warped. But bearing in mind the thermostat housing is pretty well secured with 4 studs, for some reason it has to be exactly in the right place or the coolant just pours out? If anyone is contemplating removing the thermostat housing on a 1.6, make sure its defo water tight before replacing the alternator!
 
#9 ·
I've fitted one of these twice and what a pain in the arse they are too. The first one I fitted twice because as mentioned it still leaked some so ended fitted a new rubber seal but when I fitted it, I put a little bit of sealant on the thermostat housing under the seal to hold it in place whilst locating and 2 years down the line it still hasn't leaked. For how cheap a seal is to buy it well worth just replacing it and only doing the job once. I also removed the alternator just for ease
My thermostat housing had some crusty white evidence of a leak when I first removed it. I also made a point of checking it wasn't warped. But bearing in mind the thermostat housing is pretty well secured with 4 studs, for some reason it has to be exactly in the right place or the coolant just pours out? If anyone is contemplating removing the thermostat housing on a 1.6, make sure its defo water tight before replacing the alternator!
I understand what your saying as soon as you hold the thermostat upto the block you can't slide it around to locate. Think I got 2 bolts in on a couple of threads before letting it touch the block if I remember rightly, also make sure the block is clean first
 
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