I seem to be loosing coolant on my cup-s. There's no sign of under / overheating, the heater warms up reasonably quickly and otherwise it's running perfectly. Added about 1.5l when I noticed the level was low and its probably dropped about 5cm in the tank with very minimal running since. No sign of water on the ground, although that's not surprising given the loss rate. Are there any common things to look for on this engine that could cause coolant loss?
Did you tamper on the cooling system by replacing something, thermostat f.instance? Or did you replace the coolant? How old is your car, did the loss come up suddenly or over a longer time?
Cooling system untouched by me and I'm pretty sure the coolant has never been changed before my ownership. The cars about 4 1/2 years old, 30k-odd miles. Had a poke around today and the only thing I could find that looks suspect is a very small amount of green residue on the hard pipe section of the turbo water cooling hose where it joins to the square block on the turbo housing. Plan is to get it hot and see if there's any stream, but it's a bit tricky as I suspect I'll need to get it boosting - not easy when I'm not meant to be driving unless it's "essential".
No sign of steam from that turbo water pipe. I think it will just be a case of monitoring it and if it continues I'll get it looked at when it goes in for timing belts / water pump in a couple of months time. I'm pretty sure if it's a slow leak from the water pump it wouldn't necessarily be visible without taking the timing cover off.
You need to fill the tank to the full line and get a pressure tester on it, then you can see where it leaking from
The max mark is on the top of the tank, so is it effectively almost brimmed to the top with no real expansion room? The price of a pressure tester that won't be annoyingly rubbish is about the same labour cost as getting a mechanic to do it The car has a warranty on it; I do have to pay for diagnostics but since its nothing obvious, I'll find out if that warranty is worth the paper its printed on... I'll update when I have any news.
The water level stabilised without any intervention from me. I suspect it was changed at the dealership I bought it from and there was an air lock that worked its way through.
There is a flaw with the Mk3 set up, the in and out pipes are about 2/3rds up each side, there is no pipe at the very top like the Mk2 set up, there is a bleed point but it isn't really accessible with the bumper on, so if you have had say a cambelt change along with a water pump, or a thermostat replaced, i'm sure there is a lot of air in the top of the radiator. so its possible that with high revs or hard cornering some air will make its way back into the header tank. thus the coolant replaces the air.
