Loss of coolant because of a coolant leak is probably the most common cause of engine overheating. Possible leak points include hoses, the radiator, heater core, water pump, thermostat housing, head gasket, freeze plugs, automatic transmission oil cooler, cylinder head(s) and block.
Make a careful visual inspection of the entire cooling system, and then PRESSURE TEST the cooling system and radiator cap. A pressure test will reveal internal leaks such as seepage past the head gasket as well as cracks in the head or block. A good system should hold 12 to 15 psi for 15 minutes or more with no loss in pressure. If it leaks pressure, there is an internal coolant leak (most likely a bad head gasket but possibly also a cracked cylinder or engine block).
It is important to pressure test the radiator cap, too, because a weak cap (or one with too low a pressure rating).
1. Obtain a loan free radiator pressure tester from the local auto parts stores such as Autozone, O'Reilly or PepBoys. Follow their instructions and pump it an adequate air pressure in psi allowances on the radiator cap or 12-15 psi. Observe the leaks and perform the repair.
2. Check for blown head gasket and these are the symptoms.
-The engine oil was contaminated with the coolant and there is a brown muddy color.
- Or obtain a loan free compression tester and do the test in all 4 cylinders. Any same reading at the adjacent cylinders such as # 2 and # 3, it is consider a head blown gasket.