I have a 1999 Ford Explorer XLT, 4 WD, SOHC engine, 59, 967 miles.
I noticed that when I accelerate fast that the temp goes really high, not to the red spot, but almost to the over heating area of the gauge. When I slow down it returns back to almost back to normal, but when I speed up again a minute later it gets hot again. This is in regardless if the AC is on or off. I noticed that the over tank is nasty black color, but the radiator fluid is still a nice and green ?? This just started doing this today. This was after a stressful day of bringing the GF yard saleing and stop and go and stop and go!! Could I have a blocked radiator ? Bad thermostat ? I just need to get sent in the right direction and do not want to start replacing parts I don't need.
Any suggestions would be very helpful and I would be extremely grateful.
Is the car actually getting hot, or are you basing this solely on the gauge?
I had a similar experience with my old '68 Cougar, it would overheat on the highway but around town it would run the perfect temperature. The gauge was accurate and I later found out that the issue was a defective thermostat that was stuck open.
So in summary, check the easy stuff first. Look at the temperature sensor for a loose wire and perhaps measure the resistance on it (remember that the ambient temperature will make a difference).
Of course if it is really getting hot then that is another story. Flush the cooling system and at the same time change the thermostat. If you do not buy a FORD thermostat, you will be sorry. It has an eccentric raised portion that locks the thermostat in place during installation. High quality aftermarket units do not even have this; Robertshaw, Stant, Napa, etc. Additionally it has a bleed valve to assist in the prevention of air pockets.
Also when installing the thermostat, push down on the spring of the thermostat and insert 2 aspirins opposite each other to hold the thermostat open. This will hold the thermostat open long enough to fill with water and also assist in bleeding the air out of the cooling system. Once filled, about 5 minutes, the aspirin will dissolve and prevent cooling headaches (OK I had to throw that in there). Additionally use distilled water with the coolant for best results.
I know that there is a huge difference between the cars of yesteryear and today's autos, but I think that this should put you on the correct track.
Sgt Schultz
PS Any loss of power associated with this problem? If so have the catalytic converter checked out, most muffler shops will do that for free AND IT IS against federal law to sell someone a cat if it is not required!!!
I have a 1999 Explorer SOHC. At about the same mileage as you I had the same thing happen. It turned out it was a stuck thermostat. Hope this info helps.
Is the car actually getting hot, or are you basing this solely on the gauge?
I had a similar experience with my old '68 Cougar, it would overheat on the highway but around town it would run the perfect temperature. The gauge was accurate and I later found out that the issue was a defective thermostat that was stuck open.
So in summary, check the easy stuff first. Look at the temperature sensor for a loose wire and perhaps measure the resistance on it (remember that the ambient temperature will make a difference).
Of course if it is really getting hot then that is another story. Flush the cooling system and at the same time change the thermostat. If you do not buy a FORD thermostat, you will be sorry. It has an eccentric raised portion that locks the thermostat in place during installation. High quality aftermarket units do not even have this; Robertshaw, Stant, Napa, etc. Additionally it has a bleed valve to assist in the prevention of air pockets.
Also when installing the thermostat, push down on the spring of the thermostat and insert 2 aspirins opposite each other to hold the thermostat open. This will hold the thermostat open long enough to fill with water and also assist in bleeding the air out of the cooling system. Once filled, about 5 minutes, the aspirin will dissolve and prevent cooling headaches (OK I had to throw that in there). Additionally use distilled water with the coolant for best results.
I know that there is a huge difference between the cars of yesteryear and today's autos, but I think that this should put you on the correct track.
Sgt Schultz
PS Any loss of power associated with this problem? If so have the catalytic converter checked out, most muffler shops will do that for free AND IT IS against federal law to sell someone a cat if it is not required!!!
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