1990 Mazda Truck overheating when going up hill.

1990 MAZDA TRUCK
18,199 MILES • 4 CYL • 2WD • MANUAL
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PUUNUI
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takes a while to reach normal temp. then when going up long hills like the freeway or highways it starts to overheat. when I pull over and let it idle it goes down. or if I make it over the hill and put it in neutral and roll down the temp goes back to normal.
Apr 27, 2008 at 8:09 PM
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RASMATAZ
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Test the thermostat or replace it and make sure your coolant level is correct
Apr 28, 2008 at 5:36 AM
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PUUNUI
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I just put an new one in.I filled it to the top. How can I test the water pump?
Apr 30, 2008 at 2:28 AM
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RASMATAZ
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One way to test for a bad water pump is to squeeze the upper radiator hose when the engine is hot and idling. Careful, because the hose will be HOT! If you do not feel much coolant circulating through the hose when you rev the engine, the pump may be bad. The other cause might be a bad thermostat that is not opening properly (remove and inspect the thermostat), or a clogged radiator.
Apr 30, 2008 at 7:23 AM