GM-GMC: overheating of Chevrolet truck, chevy products, heater cores

Question
I own a 1988 Chevrolet 3500 dually with a 454 engine and am having problems with blowing out heater cores and hoses.  A friend of mine put a thermostat on the truck a few years ago.  Is this the cause of my problems?  Could the thermostat be bad?  

Answer
A thermostat that does not operate properly will cause the engine to overheat, but the pressure in the cooling system is regulated by the radiator cap.  Excessive pressure is relieved by allowing coolant to flow into the reservoir.  I would check the radiator cap for proper operation and make sure that you have the correct cap for your application as they are offered in various pressure ratings.

In addition, some GM vehicles had heater hose fittings that restricted flow through the heater core.  These fittings were usually installed on the inlet hose to the heater core where the 5/8" hose attaches to the engine (intake manifold on most Chevy products).  Check with your local Chevy delaer's parts department about whether your engine should have a restricted heater hose fitting.