Hi,
Ive got the common thermostat housing leak on my st170,i want to solve this in one attempt,can some one tell me what i need to sort this out,Basically i dont want to replace the housing only for it to go again in a few months,ive read about plugs,viton o'rings,etc,but still unsure what i need to sort this out for long term
Many thanks

 

It'll be the plug seal, underneath the thermostat housing. Ford will try and sell you the complete housing but the plugs and seals are available seperately!

 

Mines loosing coolant aswell.....Fords supply bung & 0-ring £7

 

Aye you only need the little seal circled, easy job

 

Which bit of that is a thermostat housing?









it's here, although upside down in picture, the bung and seal fits in this hole, underneath at the front as you look at it.

 

I noticed the same leak in my RS yesterday. I am ordering a housing and thermostat tomorrow. Priced around today. Bought a rubber ring thing off Ford yesterday and was going to change it today but was told I'd be better of chnaging the lot, the housing, thermostat the the Yellow cap of the coolent bottle.

Are they the same parts on both cars.

 

No the RS has an offtake for a water feed to the turbo. Unless the Thermostate housing is cracked dont change it.

 

Update

The housing needed replacing in the end,so bought a new one(ford prices)
Noticed that it didnt come with the bung,so had to buy a new bung and replaced the o-ring on it with a viton 203#one from a local seal/o-ring company all for a costly £1-20 for 4,my mate replaced all this and so far 2-3 weeks on its all good,no more leaking