What can make an engine overheat?
Overheating is caused by anything that leads
to a loss of coolant, prevents the cooling system from getting rid of
heat, or causes excess heat in the engine itself:
leaks (water pump, radiator, heater core, hoses, freeze plugs, head
gasket, engine internal).
radiator cap (does not hold rated pressure and allows coolant to boilover).
Pressure test the cap to check it out.
system clogged (deposits built up in radiator or in engine due to maintenance
neglect or use of hard water). Use a cleaner, then reverse flush the
system to clean it out. A badly-clogged radiator may need to be rodded
out or replaced.
stuck shut (replace).
electric cooling fan (check fan motor, relay and temperature switch
for correct operation).
fan clutch (replace if slipping, leaking or loose).
fan shroud (reduces cooling efficiency of fan).
fan belt (tighten or replace).
low or too high a concentration of antifreeze (should be 50/50 for best
water pump (impeller eroded or loose - replace pump).
radiator hose (check lower hose).
in the radiator (remove bugs and dirt).
ignition timing (reset to specs).
exhaust system (check intake vacuum readings and inspect converter,
muffler and pipes).
and/or fan undersized for application (increase cooling power by installing
larger radiator and/or auxiliary cooling fan).