I was driving my 240D to a friend's house and got caught in a construction back up. As I was sitting with nothing much to do, I checked the gauges and noted that suddenly the temp gauge spiked up to 120. I revved the engine, turned on the heater to full heat and the temp came down to 90.

Upon arriving at my friend's house and letting things cool down a tad, we opened the radiator cap and we could see the top fins of the radiator and no coolant in sight. We added quite a bit of water (the 240 does not have a coolant recovery tank) to both the radiator and the coolant flush port that had been spliced into the heater hose. There was no coolant evident in the heater hoses either. With the radiator refilled, and no construction on the way back to WHunter's house the temp gauge read 80-85.

We did a pressure check at Whunter's house. The system held pressure at 12 psi with no apparent leaks on the hoses, radiator, or water pump. We released the pressure and started the car. Pressure started to build on the pressure gauge. The diagnosis: a bad head gasket which is pumping air into the cooling system. When the pressure gets high enough the radiator cap allows liquid to escape and the air has displaced the coolant. This new issue is a slow air leak into the coolant system. It isn't huge, but if unattended, it could cost the life of the engine.

We will remove and replace the head gasket in a couple of weeks. I will let everyone know what we found with some pictures. Right now there is nothing (photographically) that can be seen. The car is out of service for a while... but I have spares.

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Pete Williams, President emeritus - MBCA-International Stars (Eastern Mich.) Now Wi. & Az.
1985 300D Manual 4 speed Green Hen's tooth
1979 MGB triple black Az car nice
1969 back 1/2 of MGB (Az home built trailer)
1991 Volvo 245 Wagon Nice AZ Restored Gold Brick
1983 Jeep CJ7 37,600 Miles Summer use only