Engine: D5: Do I have a leaking cylinder head gasket?

[rogereld]

Have you checked your heater matrix is not leaking inside the car?

[skv70d5]

OK, I have performed a cold start test (remove cap to release pressure from the day before, refit cap, run engine for 20 seconds, undo cap) and there was a slight hiss; however, the expansion tank only smelt of coolant.

I then turned over the caps rubber seal (tip from ChesireD I found in a different post), used the car for a couple of days and then performed the cold start test again. This time there was no hiss what-so-ever, and the tank still only smells of coolant.

[skv70d5]

Originally Posted by rogereld

Have you checked your heater matrix is not leaking inside the car?

I have checked under the floor mats on both sides of the car and did not find any damp or dried coolant deposits.

[rogereld]

Originally Posted by skv70d5

I have checked under the floor mats on both sides of the car and did not find any damp or dried coolant deposits.

My heater matrix was probably leaking for more than a year before I found the leak. In my case lifting the footwell mats revealed nothing. You need to remove the interior lower side trim panel alongside the centre console (turn one clip with a coin to remove) and then you can see where the silver metal pipes connect to the plastic heater core. I found evaporated traces, green and white, on the inside of the trim panel and around the pipe connections. I had been losing 1/2 to 1 litre of coolant every few months and got a "coolant Low" dashboard warning a couple of times a year.