Overheating woes don't have to be a mystery. Find the fix now.
Classic Mustangs, especially, have always been plagued by overheating problems. However, these overheating problems didn't become chronic until these cars got some miles and years on them. Radiators scaled up. Thermostats went bad. Valve jobs went back together with head gaskets installed backwards. Neglectful and careless engine rebuilding technique. Improper fan selection and installation. Not enough radiator capacity. Improper engine tuning. Lower radiator hose collapses at high rpm. Freeze plugs left inside block and/or cylinder heads during rebuild.
Here are some common overheating causes.
* Thermostat Stuck Open or Closed
* Improper thermostat temperature
* Improper Fan or fan installation
* Insufficient fan for installation
* Improper fan depth in fan shroud
* Fan clutch out of fluid (not turning at normal speed)
* Water pump belt slippage
* Improper water pump pulley, crank pulley size
* Lower radiator hose collapse at high rpm (overheats on the interstate only)
* Improper water pump for application (forward rotation water pump where reverse rotation belongs)
* Freeze plugs left in block or heads
* Cylinder head gaskets installed backwards
* Blocked cooling passages (between heads and block)
* Extremely lean fuel mixture
* Improper ignition timing
Engines overheat whenever an engine makes more heat than the cooling system can remove. That's why proper heat transfer is so important. We don't want to remove too much heat - just enough to keep an engine safe. Never remove a thermostat thinking you will fix your overheating problem. The thermostat is your cooling system's traffic cop. It regulates the flow of coolant from the engine to the radiator and back into the engine again. When you remove the thermostat, you disable the radiator's ability to retain coolant and transfer engine heat. Classic Mustangs should have a 160 or 180 degree F thermostat. Late model, computer controlled Mustangs get a 192-195 degree F thermostat.
Improper engine tuning will also cause an overheat. Lean fuel mixture. Improper ignition timing. And even improper valve timing during a cam swap or engine build.
And no matter what anyone, including manufacturers, will tell you - when you install a molded lower radiator hose, you must have a stainless steel anticollapse spring inside the hose. Otherwise, count on hose collapse and overheat when you pin the butterflies.
Finally - no matter what kind of coolant you use, always add Water Wetter to improve surface tension (coolant contact with water jackets) and prevent corrosion.