Just wondered if anyone could help, my brother has an astra mk3, and has been having trouble with the cooling system, the temp dial never raises even when engine is hot, it hovvers above the blue mark. Lately he has been getting a sqweeling noise coming from the cambelt route, which is either the water pump or tensioner. So last night i put some water pump lube in the system to see if it solves the problem but doesnt appear to have. What does it mean if the car is driven 20 miles but the water in the system doesnt even get slightly warm. Could it be the thermostat, also could it have a dodgy temp sensor. Another question is, do you have to take the cam sprocket off to take the cam belt back cover off. Because it appears that to get the thermostat out, the cam covers/belt need to come off.