MG Car Repair: 78 MGB over heating, head gasket leak, cruise speeds

Question
I finally got the gauge to work by replacing the sensor. The fan does not come on and after a few minutes the gage will go all the up. Besides the fan not working what else do I need to check/fix to keep it cool?

Answer
Hi Larry,
You need to get the fans running first to see if that is your overheating problem, although at speeds over 35 MPH the fans are not much use anyway so does it overheat at highway cruise speeds? If so you can figure that you probably have other problems too.
Some simple tests will help pinpoint the problem.

Crank it up cold and put a electric fan in front of the car while it warms up and you continuously check the upper hose for heat. It should get very warm to the touch long before the temp gauge starts showing hot. If it don't then you either have a bad thermostat or a water pump problem.

If the upper hose does get hot then the thermostat and water pump are probably ok and you should get some of the test dye from your auto parts store to put in the radiator to test for CO in the coolant which is a sign of a head gasket leak or crack in the head. (Gasket most likely)

To test the fans turn the key on an jump between the two pins of the fan sensor in the radiator on the right side. If the fans Don't come on you need to start testing the fans them selves and then the wiring for the fault.
Howard