1997 explorer

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Nov 19, 2014 | 11:26 AM

milkman713

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1997 explorer

I have a 1997 explorer XLT 4.0 SOHC. I just changed the water pump and now the temperature guage fluctuates. After driving a mile or so with no warm up time i start to get a little heat. When the guage gets to normal running temp it will drop to cold then I would loose heat. it would gradually return then drop I am confused and was wondering what cause this to happen. Any sugestions?

Nov 19, 2014 | 12:44 PM

shorod

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Joined: Jun 2009

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From: Cedar Rapids, IA

From your description it sounds like you have air trapped in the cooling system. The air passing the Engine Coolant Temperature sensor causes the fluctuations in the gauge reading. Trapped air is pretty common when cooling systems are drained and refilled. Some engines have air bleed screws located high on the block, but I don't think your engine is one of them. Instead you will probably need to park on an incline with the nose of the truck pointing upwards, release the radiator cap to the first notch so it won't allow the system to build up pressure, then start the engine and let it get up to operating temperature and open the thermostat. This should allow the air to find the highest point (ideally the pressure cap) and escape. After you're comfortable the majority of the air has escaped, top off the radiator and fully install the pressure cap.

-Rod