Here's a quick check for seep leaks at the head gasket- - - -Remove the thermostat housing and the fan belt, and fill the engine up with water until it's level with the thermostat area. Run the engine, and goose the throttle a couple of times before the water in the engine gets too hot due to non-circulation. Bubbles, or coolant forced out of the thermostat casting indicate a pressure leak at the head gasket. From your description of the symptoms, I'm guessing you've got a radiator problem. Back-flushing the radiator helps sometimes, but you're probably going to have to do a rod-out or a recore. To backflush, remove both hoses at the engine, and rig an adapter in the lower hose to let you run a garden hose into the lower hose connection. Run the hose full force, and make the water flow backwards to its normal running direction. If you adapt a blow gun to the lower hose connection, you can also blast compressed air into the lower hose while you're back-flushing, giving the water a shock effect. It's surprising how much crud can be cleaned out of a radiator that appears to be in good shape that way.
Jerry
