Temp gauge question

[Dave98XLT]

98 Explorer. Engine is off but warmed up, should the temp gauge be in the warm position or should it go back down to cold when I turn the key off?

My gauge is reading funny and I'm trying to determine if it's the gauge the sender the thermostat or what have we

So if anyone can tell me how there's is working when the key is off and the engine is warm that would be a good first step

 

[koda2000]

When the ignition key is turned off the fuel level and temp gauges remain in the position the needles were in. The chg and oil gauges drop to their lowest settings.

The temp gauge is not really a gauge (a bit like the oil pressure indicator). The temp indicator will read about in the center (slightly less) when the coolant temp sender finds the coolant temp w/in a "normal" range (maybe 163-210 degrees F). If the coolant temp is below/above the range the needle will go to "C" or "H". To know your actual coolant temp you need something like FORscan to see the PCM's reading

 

[Dave98XLT]

Koda the gauge is reading up near the high point and comes down to about three quarters after running. I checked the coolant pipe by the thermostat with a infrared gauge and it's reading around 185. Would the most likely problem be the gauge or the sender? Or something else?

 

[koda2000]

Koda the gauge is reading up near the high point and comes down to about three quarters after running. I checked the coolant pipe by the thermostat with a infrared gauge and it's reading around 185. Would the most likely problem be the gauge or the sender? Or something else?

The sender is easy to change and not expensive. You might as well try that first.

 

[Dave98XLT]

If I can figure out where it's located can you give me a clue on a 98 sohc motor thank you

Edit is it the one right behind the thermostat housing? There's a small amount of leaking coolant there so that really makes me think that's what the problem is either electrical connection or otherwise

 

[koda2000]

There are two mounted to the top of the black plastic thermostat housing. One is for the PCM and is a SENSOR and the other is for the gauge and is a SENDER. They look the same from the top and are right next to each other. I think the one on the right (looking from the front) is the one for the gauge but I'm not 100% sure. Check a wiring diagram to be sure.

Note: Your year SOHC has the screw-in style sensor and sender. Later models had push-in sender and sensor. It is possible that when you try to unscrew the sender that the brass threaded piece will twist in the plastic housing causing a leak.

PCM Sensor (note the pointed tip, some have a knob):

PCM Sensor w/knob style tip:

Gauge Sender (flat tip):

Also note that the pointy tip and knob tip senors appear to take a different electrical connector.

 

[Tasco37]

Or maybe a wrong/half stuck thermostat.

I have a similar problem with mine. On hot days my temps are normal. But on cool/cold days I can barely pass a 1/4 the way up the gauge. If I leave the heat off I might be able to hit normal temp, but as soon as I turn the heat on, it lowers.

So I figured one of three things:

Stuck thermostat
Wrong temp thermostat
Coolant not properly mixed

All which I assume was happening before I got the truck last Dec.

 

[donalds]

Or maybe a wrong/half stuck thermostat.

I have a similar problem with mine. On hot days my temps are normal. But on cool/cold days I can barely pass a 1/4 the way up the gauge. If I leave the heat off I might be able to hit normal temp, but as soon as I turn the heat on, it lowers.

So I figured one of three things:

Stuck thermostat
Wrong temp thermostat
Coolant not properly mixed

All which I assume was happening before I got the truck last Dec.

Stuck thermostat . Had the same problems
Change it and put a metal thermostat housing just my .2

 

[koda2000]

Yes, I agree it could be the t-stat if you haven't replaced it already (and even if you have, it's not unheard on to get a defective t-stat). I recommend a Motorcraft brand t-stat for the SOHC engine, they're pricey, but seem to work best.

 

[XLTrunner]

It's more than just a possibility that when you try to unthread the gauge sender that it will strip out inside the housing...it's almost a certainty. Not only have I experienced it with my own vehicle...but, with a half dozen or so at the U Pull. So, better have a backup plan for replacing the entire housing.

 

[donalds]

This is what I did with with that pos housing and sensor
You can bet it will strip 100%

 

[poker4me007]

This is what I did with with that pos housing and sensor
You can bet it will strip 100%

View attachment 162950

At that distance it never had a chance.

 

[donalds]

At that distance it never had a chance.

Dam Skippy

 

[donalds]

I got sick after replacing like 5 of them in a 2 year period

 

[Dave98XLT]

Thanks, this was very educational.

Should I go with the metal replacement housing?

Are there any hidden landmines if I go ahead and replace all of the cooling system hoses while I am in there?

 

[donalds]

I would go with the all aluminium housing
Which one up to you
As far as the hoses I don't see where there would be a problem

 

[Dave98XLT]

Any opinions on the Dorman upgraded housing assembly Autozone sells?

 

[donalds]

Any opinions on the Dorman upgraded housing assembly Autozone sells?

Don't buy it
Well unless you like changing them lol

Get the motor craft or. A metal one

 

[donalds]

4.0 SOHC Metal Thermostat Housing Comparison


Read this

 

[koda2000]

Don't buy it
Well unless you like changing them lol

Get the motor craft or. A metal one

Never buy anything Dorman if there's another choice. Their stuff is generally junk. I recommend getting a metal t-stat housing as my first choice and a Motorcraft if you're going to stick with plastic. I'd also recommend switching to the push-in style sender/sensor.