Engine Temperature Gauge is acting up

[MarkT302]

Hey everyone! Just wondering if anyone could lend their expertise on this subject. I just recently went down to Missouri to buy a rust free 2000 Explorer. It has 113,000 miles on it. The temperature gauge on it always creeps up really high, sometimes it even snaps up, but then it drops back down. I put in a new Motorcraft thermostat, and the gauge is still showing the same thing. Even when the gauge says that the engine is really hot, the upper radiator hose is just warm, not hot. The radiator cap also isn't very warm at all. I replaced the radiator cap, and it still does this. The radiator seems new, and beefier, so maybe it just runs more efficiently? The thermostat housing is at around 159 degrees when the engine is up to operating temp. I ordered a new coolant temperature sensor that should arrive in a few days. Hopefully this fixes it. Any tips are appreciated!

 

[PAExplorerXLT]

Over the years I have seen a lot of cars that overheated but the upper radiator hose was cold. In my experience it was always caused by some kind of air lock. I don't know if the Explorer has bleed valves although theoretically cooling systems with an expansion tank are supposed to get rid of trapped air by themselves.

 

[koda2000]

have you replaced the temp sender?

 

[my98nnj]

Clean the electrical connection at the sensor. See if that stabalizes it.

 

[MarkT302]

Thanks for all the tips! I'm waiting on the coolant temperature sensor to arrive in the mail, then I'm putting that in to see if that's all it is. I burped the system a few times to get as much air out as I could. I think all the air is out of the system. I took temps of the thermostat housing when the engine temp gauge said it was overheating, and the housing was only 172 degrees. I'm pretty sure the sensor should..SHOULD take care of it. *crosses fingers*

 

[koda2000]

Thanks for all the tips! I'm waiting on the coolant temperature sensor to arrive in the mail, then I'm putting that in to see if that's all it is. I burped the system a few times to get as much air out as I could. I think all the air is out of the system. I took temps of the thermostat housing when the engine temp gauge said it was overheating, and the housing was only 172 degrees. I'm pretty sure the sensor should..SHOULD take care of it. *crosses fingers*

sender and sensor are two different things. the sender is what works the temp gauge. the sensor tells the PCM what the coolant temp is. which one did you order? also, if you have the 4.0L SOHC engine it is quite likely you will break the plastic thermostat housing and create a leak when changing either the sensor or the sender. that housing is a pretty pricey part.

 

[MarkT302]

Sensor vs Sender

I ordered the sensor(Motorcraft). I have the 5.0! I see you do as well

 

[BustedKnuckles24]

Have you looked at the CTS sensor with a scan tool? It is a separate sensor for the computer, not the gauge. At least it will confirm the sending unit is right or wrong.

 

[koda2000]

the gauge has nothing to do with the SENSOR. you need (maybe) the SENDER.

 

[MarkT302]

Sender

I guess I better order a sender then! Is it by the sensor itself?

 

[masospaghetti]

The sender is positioned vertically on the lower intake manifold, just forward of the intake plenum. It has a single wire going to it.

I actually had the same problem with mine but the sender wasn't the culprit. The circuit that drove the gauge itself was bad. I had to replace the gauge cluster circuit board to fix it. Luckily, its relatively easy to replace the circuit board once you get the cluster out, since all of the gauges literally snap in.

But first, try the sender and see what happens.

 

[MarkT302]

Gauge Circuit

Thanks! I'll see if that works for me!