heating problems

[katt68]

92 4.0 ex is acting weird. she will head up beyond normal by the gauge, boil over in the overflow tank, blow cold air through the vents when she is heating, then all of a sudden drop off to back to normal. i have replaced the thermostat but the problem still exists. please help.

 

[RiverRat]

How is the fan clutch?

 

[RiverRat]

Fan Clutch Test:
With engine off spin the fan. A light resistance should be felt. If there is no resistance or very high resistance, replace the fan clutch.

Other things can cause overheating:

Damaged water thermostat.
Damaged water pump.
Internal engine coolant leak.
Plugged radiator.
Loose/damaged drive belt

 

[Alec]

This thread is very similar to your other:

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