Dear fellow forummers,my car has been very tempremental lately. after two hours of driving, (worst if caught in traffic) the car tempreture will start increasing and need to halt. i notice that the water level in the radiator is so low.i don't think is's because of radiator cap or water pump because i've replaced these two item before, so i suspect it is due to the blown head gasket.if so, how much does it cost to replace a blown head gasket on a e34 m50b20?thanks and regards.