Trapped air within your Fox Body's cooling system can cause your Pony to overheat and can cause engine problems. Burping your coolant system is an easy task, follow along with the article below to show you how this task is completed!
Whether you are doing a fresh engine rebuild, performing a coolant flush, or changing out hoses and a water pump, air in your cooling system is something you cannot avoid. These easy steps below will show you how to properly burp your Mustang's cooling system.
To begin, make sure you have a few gallons of properly mixed 50/50 Motorcraft (or equivalent) coolant and distilled water. This premixed coolant will ensure that you always have the proper ratio introduced into your cooling system. Also, make sure to visually inspect your engine for any obvious leaks. Make sure to address these before going any further if any are present. The cooling system within your Mustang is a sealed system; if there are any leaks or the system is open, air can be introduced.
With the engine cool, go ahead and remove your radiator cap. Insert a funnel into the opening and top off your radiator until it is full. Start the engine and allow your car to get to operating temperature. The key here is to keep the coolant level full without letting air get back into the system. Having a buddy inside of the car will also help here so the vehicle temp can be monitored. You want the car to get hot enough for the thermostat to open fully. Once the thermostat opens, you may see a drastic drop in the coolant level. Keep adding the coolant mixture accordingly until you see the levels even out.
With the funnel still in place on the fill area of the radiator, make sure the coolant level is above full; any residual air will come up in the funnel as bubbles. A good trick here is to squeeze both the upper and lower hoses, this can help move any air pockets that may be trapped. Normally, let the thermostat open a few times to ensure as much air is removed from the engine block and all other areas of the cooling system.
Reinstall your radiator cap and top off your overflow bottle to the fill line marked on the side of the bottle. Double check the system for any leaks. You can now take the car for a test drive. Make sure to take your coolant with you just in case you need to add more if your temps begin to rise above normal operating them. Make sure you allow the car to cool down completely if you have to add any more coolant. Opening the radiator cap when the car is hot can be a very bad thing to do!