MG Car Repair: 1974 1/2 Mgb overheating slow leaking radiator.., head gasket problem, coolant levels

Question
I own a 1974 1/2 Mgb that has recently started overheating... When I first
noticed that the tac was a little over N I shut the car off hoping not to do
further damage... I checked my belts and water/coolant levels whitch  were
fine.. Let it cool, then drive it home... It now overheats and seems not
getting good coolant circulation... I am thinking maybe thermostat? Idk... If
someone can throw me some ideas where to start I would be very
grateful...

Answer
Hi Zack,
First start it up cold and feel the upper radiator hose and as it warms up note the temp of the upper hose. This is a rough test to see that the thermostat is opening. If the upper hose seems to match the gauge reading get a meat thermometer and when it is hot open the cap (with a rag over it so you don't get sprayed with hot coolant if it is really hot) and check the coolant temp to confirm that it is really hot.

If it is hot, get some of the dye from any auto parts store and test it for CO. If you have CO in the radiator you have a head gasket problem or a cracked head.

Other things that can make a car over heat are, incorrect ignition timing, too lean mixture on the SU carbs, water impeller loose on the shaft, stopped up radiator and Lower hose coming apart inside.

Howard