1998 Ford F-150 Temp gauge pegs HOT

PAPPY2015

MEMBER
1998 FORD F-150
4.6L
V8
RWD
AUTOMATIC
331,000 MILES

My 98 Ford F-150 4.6 jmhas this problem were in would peg HOT after ten to fifteen minutes of driving. It's not overheating because it didn't get enough time too. Plus the upper radiator hose is not hot. It has pressure on that hose but not hot. I replaced radiator, water pump, three different thermostats(190f, 192f, and 195f). Dealer pressure checked it. Came back ok. One thing I notice is that before it pegs HOT the temp gauge will fall a little then spike all the way up. Any help please?

Tuesday, November 10th, 2015 AT 4:04 AM

3 Replies

JDL

MECHANIC
16,098 POSTS

The dealership couldn't track down the problem? Any applicable trouble codes related to instrument cluster or temp sensor? Some of the national brand auto stores will check codes for free. I think ford calls the temp sensor, cylinder head temp sensor.

Could be issue with wiring connector or wiring circuit for the temp gage/instrument cluster or sensor. I realize I'm throwing a wide loop. Maybe one of the others has better info?

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Tuesday, November 10th, 2015 AT 9:14 AM

PAPPY2015

MEMBER
3 POSTS

The dealer couldn't track it down. And the auto parts stores said they can't do it if theirs no engine on. Forgot to mention that I also replaced temp sending unit.

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Tuesday, November 10th, 2015 AT 11:01 AM

JDL

MECHANIC
16,098 POSTS

All I can do is tell you to check the cts wiring circuit. How many wires to the sensor, 2? If two wires that should be voltage and ground, key on, use digital multimeter.

You could take those wires loose on both ends and do an ohms test.

Maybe instrument cluster--computer--or a wiring circuit somewhere.

Maybe you have air in the coolant system, that can effect your gage.

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