Leaking K series thermostat

[cj247]

Have new 1.6 K series but don't seem to be able to stop the thermostat housing leaking when car is cold (puddle on garage floor but coolant remains above minimum). Have removed & replaced O ring with genuine Rover spare, sprayed with silicon spray, & re-assembled but it still leaks. It wasn't a tight fit when I put it back together but I couldn't feel any rough or damaged areas in the hole in the engine housing.

 

Before I try again with a new thermostat housing I thought I ask if anyone has any tips? For example, do I wrap a bit of PTFE tape in the O ring groove on the thermostat housing to get the O ring to stand proud, or is there a danger that this could come loose & block the waterways?

 

Car is less than a year old & only done 1300 miles

[c7trp]

I had a similar problem last year.

 

In the end I found leak was actually due to the rubber seal on the thermostat not being properly seated leading to a leak between the two halves of the stat body.

 

The housing is not a tight fit into the water pump body, looks like the obvious spot for it to leak.

 

I bought a new housing in the end, and only when transferring the stat from old to new housing did I find the rubber seal on the thermostat was not fitted properly. 😔