C4 grand space tourer 2.0hdi coolant leak

[Paul73]

Hj all, our generally very reliable 2.0 HDI has a coolant leak. It broke down on the M5 last week and despite the roadside recovery chap topping it up and pressure testing it. 4 miles later it ordered my wife to stop so it was recovered.

I've pressurised it to 20 psi and it does lose about 2 psi and about 8mm fluid height from the middle of the expansion tank in 10 minutes.

Is there a likely cause I should look for first and secondly, the "mat" under the exp tank is wet so can anyone tell me how to get the tank out?!

Many thanks all!

[mickthemaverick]

The first thing to check is that the expansion tank cap is not cracked and then examine the corners of the tank for hairline cracks. Also check the hose connections around the engine, radiator and heater matrix as well as the thermostat housing and water pump mounting.

[Paul73]

The first thing to check is that the expansion tank cap is not cracked and then examine the corners of the tank for hairline cracks. Also check the hose connections around the engine, radiator and heater matrix as well as the thermostat housing and water pump mounting.

Cheers. I did wonder about the cap myself, but as I'm pressuring it with a tool then that's out of scope as it's not currently fitted!

Might need to get some more proper fluid as clear water is hard to see small leaks with!

Any idea on expansion tank removal??

[mickthemaverick]

Not precisely but usually a mounting underneath to be released and possibly a stabiliser at the back or side.

[Paul73]

The reservoir level appears to have recovered after taking the pressure back off. Perhaps it is just the cap??