Thermostat issue?

[FritzTKatt]

Can't find anything in the search... 94 4.0l, yesterday morning (didn't notice on friday) the temp gauge decided to act weird. I let the truck warm up for a good 10 minutes, which usually gets it just below running temperature, even on a freezing day (which it wasn't).

Noticed a few minutes down the road I was still cold, but the heater was blasting as usual. Then intermittently, the gauge would read cold, normal, a touch above normal, back to cold, back to above, cold, normal... Heat didn't change, and the truck ran the same.

I'm thinking thermostat or the sending unit or whatever it is that controls the gauge. Although thermostat would make it run HOT because it's stuck closed? Or not heat up at all being stuck open?

 

[killj0y]

I would test the temp gauge :thumbup:

 

[wildbill23c]

Could be the temperature sensor, the gauge, or lose connection somewhere.

 

[AllanD]

CLEAN(wirebrush & smear with electrical ant-corrosion paste)
both ends of the engine block ground wire that runs from the back side of the drivers side cylinder head to the stud on the wiper motor.

Likewise remove the wire on the guage sender squeeze the connector smear it with anti-corrosion paste and reinstall.

You have a guage issue.

AD

 

[FritzTKatt]

Ok, that's what I was thinking. I remember before I blew a water pump in my 94 2.3l it was reading hot at idle, then driving it would cool back off to below normal from the air circulation. Since it wasn't getting HOT, figured it was something simple. Thanks, I'll check out those connections tomorrow if I get a chance.

I know where the top of that ground strap is going, but any advice on getting to the bolt on the block? Remember what size it is off the top of your head? Maybe save me a few minutes of playing with wrenches/sockets.