Hi all. I have had an issue with a small amount of coolant being lost graduallly over periods of time. I would fill up the expansion bottle and check it again a month later and find that it was back on the minimum. I couldn't see any visible leaks so just kept topping up. Then the other day I visited my parents and they called to say had I got a leak? I had a look around the car and found a small amount of coolant dripping from the undertray. I had a look and feel around the car and couldn't really see anything until I accidentally touched the coolant temperature sensor, which is mounted in the thermostat housing. Everytime I touched it my hand got coated in coolant and it was very loose. Its only held in by a spring clip but is in a very difficult place to get to. I went down to my local dealers and purchased a new sensor and sealing 0-ring gasket. And a couple of bottles of G12 coolant.
I waited for the car to cool down and then managed to get the spring clip out to find the 0-ring gasket was completely shot. Perished and very little left. Installed the new gasket and sensor (which I didn't really need) and then fiddled around until I got the spring clip back in place.
Now all sorted and coolant seems stable.
Cost me about £40 with the sensor but could have just been £1.06 for the 0-ring and some G12 if I wanted to try and return the sensor.
Well pleased as I was fearing the worst as I had read about thermostat housings leaking, which given the location looks very fiddly to change.
Hope this helps anyone else with a similar undetectable leak.
I waited for the car to cool down and then managed to get the spring clip out to find the 0-ring gasket was completely shot. Perished and very little left. Installed the new gasket and sensor (which I didn't really need) and then fiddled around until I got the spring clip back in place.
Now all sorted and coolant seems stable.
Cost me about £40 with the sensor but could have just been £1.06 for the 0-ring and some G12 if I wanted to try and return the sensor.
Well pleased as I was fearing the worst as I had read about thermostat housings leaking, which given the location looks very fiddly to change.
Hope this helps anyone else with a similar undetectable leak.