WHY IS MY TRUCK OVERHEATING?

1999 Ford F-150

Tiny

jerryshows

September, 8, 2012 AT 3:18 PM

I have a 1999 F-150 4.2 litre V-6 with 218,000 miles. If I turn on the AC it will overheat. It does this even while driving down the interstate at 70-75 mph. What could it be?

FOUND 13549 RELATED QUESTIONS

3 Answers

Tiny

ASEMaster6371

September, 8, 2012 AT 3:23 PM

Possible causes
clogged radiator
low coolant level
bad thermostat
water pump impeller(common on fords)
blown head gasket which may be an issue with you as it sounds like you are driving it overheated

Roy

Tiny

jerryshows

September, 8, 2012 AT 7:13 PM

Coolant level is fine, am not driving it overheated as I monitor temp gauge and turn air conditioner off and pull over when it heats up also there isn't any water in the oil nor does it puff white smoke out of the exhaust when I crank it, why would the thermostat work when the a/c is off and malfunction when the A/C is on? How would I check a bad impeller on the water pump?

Tiny

ASEMaster6371

September, 9, 2012 AT 2:27 AM

Thermostat can be partially open but I doubt it.

Water pump would have to be removed to verify impeller.
Leak down test will confirm head gasket

my gut is a bad radiator.

Roy

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