Feeling a little hot around the collar? Maybe your cooling system needs a second look and a thorough check-up.
There are so many misconceptions about engine overheating. But, the basic fundamental cause of overheating is your Mustang's cooling system's inability to transfer heat to the atmosphere efficiently. If your engine runs hot, it is making more heat than the cooling system can remove. So why the overheat?
When you're troubleshooting a bothersome cooling system, you cannot overlook anything - even if the wild guess seems remote. Here's a quick bullet point checklist of things you need to inspect if you've got an overheating problem.
* Debris in the water jackets - old freeze plugs, casting slag, metal wire from the sand casting, hardware such as nuts, bolts, washers. Don't laugh - we've seen all of it at least once. When all else has failed, start removing freeze plugs for a look into your engine's water jackets.
* Radiator cooling fins. There are no unimportant fins or tubes. If fins are damaged, air cannot pass through them to remove heat. If tubes are deleted due to damage and leakage, this makes your radiator that much less effective. Replace the radiator.
* Blocked cooling passages due to excessive gaskets sealer, distorted hose tubes, a collapsed lower radiator hose (high rpm only), closed thermostat, deteriorated hoses (internally), corroded/contaminated water pump impeller and pump passages.
* Cast iron and/or aluminum particles that have passed into the radiator from your Mustang's engine and clogged cooling tubes. Examine coolant flow through your Mustang's radiator at operating temperature with thermostat open.
* Not enough radiator for application (air conditioning, high-performance engine, etc.)
* Faulty fan clutch on Mustangs so equipped (is the fan turning at pump speed?)
* Faulty thermostat (thermostat won't open).
* Thermostat missing entirely.
* Improper thermostat for application.
* Improper fan depth in shroud or no fan shroud where one needs to be.
* Air pockets in cooling passages because system was not burped after servicing.
* Cylinder head gaskets that have been installed backwards (cooling passages at the wrong end of block deck - V-8s only).
* Crushed or dented exhaust pipes and/or header tubes. Not only will this make an engine run hotter, you are at high risk for exhaust valve failure from extremely high combustion temperatures.
* Extremely lean fuel mixture - especially under a load.
* Ignition timing advanced too far.
Even when some of these bullet points may seem remote, check it anyway. Double checking the not-so-obvious can save your neck.
Under no circumstances do you ever operate your Mustang without a thermostat. The thermostat is there for a reason, to allow coolant time to give up heat at the radiator.
Cooling systems should always be operated with a radiator cap in the closed position to allow the system to build pressure. The higher the pressure, the higher the boiling point of your Mustang's coolant, which reduces chances of a boilover in hot weather.
Running the right mix of ethylene glycol and water will also raise your coolant's boiling point. Mark Jeffrey of Trans Am Racing in Gardena, California suggests running 100% ethylene glycol or 100% Evans non-aqueous coolant to eliminate any chance of cooling system corrosion. Although 100% antifreeze may turn some of you off, it will not harm your engine. The down side is, antifreeze doesn't transfer heat as well as 100% water. However, 100% water will damage your cooling system from corrosion.
When possible, run a cooling system filter in your Mustang's upper radiator hose to catch debris such as iron and aluminum particles, gasket sealer, and other crud that can clog your radiator. Check the coolant filter every time you check oil and fluids. If the engine begins to run hot, check this filter.
Never do it on the cheap. Invest in the best hoses, clamps, water pump, thermostat, gaskets, radiator, and the right cooling fan. Use an anti-collapse spring the the lower radiator hose no matter what anyone tells you. Although some hose manufacturers will tell you this spring isn't necessary, they are dead wrong. Highway driving and high rpm operation can cause the lower radiator hose to collapse and cut off coolant flow.
Always use the correct diameter drive pulleys for your application. Using a water pump pulley that's too small and/or a crank pulley that's too large will cause your water pump to turn too fast causing hot spots and too much coolant flow through the engine and radiator as rpms increase.
Always seek proper fan depth in your shroud. Too deep or too shallow and your radiator will suffer with air flow problems. The fan should be half-way into the shroud for optimum air flow.
When it comes to cooling system woes, always check what isn't so obvious - what others would never think to check. Sometimes, it just isn't what you think it is.