96 Explorer 4.0 OHV temp gauge stuck on cold. HELP! | Ford Explorer Forums - Serious Explorations

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96 Explorer 4.0 OHV temp gauge stuck on cold. HELP!

Swordfish94x

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City, State
CA
Year, Model & Trim Level
1996 4dr 2wd Explorer
Hey so I have a 96 XLT with the OHV, my dad tells me we've had this problem for years, and I just got the Explorer from my Grandpa because she passed away. No matter how long I warm it up for or drive for the gauge stays between the little c and the bottom line and will never go above it. I know for sure that my engine warms up and the heater/AC both work no problem. I was first thinking that someone had taken the thermostat out, but my grandma only ever got it serviced by the dealership, and even if it was taken out the gauge would eventually warm up a little bit.

I was reading online and a few people replaced their temperature sending units and it worked again, so I tried it and nothing changed. I don't think it's the sensor because I know the engine warms up. I'm stumped on what it could be. I want to get it fixed because if it ever did start to overheat I wouldn't know until it actually happened, so any advice or anything could really help. Thanks!
 



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I was reading online and a few people replaced their temperature sending units and it worked again, so I tried it and nothing changed. I don't think it's the sensor because I know the engine warms up. I'm stumped on what it could be. I want to get it fixed because if it ever did start to overheat I wouldn't know until it actually happened, so any advice or anything could really help. Thanks!

Make sure you changed the correct temp sending unit; there are seperate ones for the gauge and the ECU. Usually, the gauge sender has one wire (red/white I believe) and the ECU temp sensor has two wires. Unplug the wire for the gauge at the sending unit and ground it; the gauge should read max H. If it doesn't, the gauge itself or a connection within the insturment cluster is faulty. Good luck.
 






Make sure you changed the correct temp sending unit; there are seperate ones for the gauge and the ECU. Usually, the gauge sender has one wire (red/white I believe) and the ECU temp sensor has two wires. Unplug the wire for the gauge at the sending unit and ground it; the gauge should read max H. If it doesn't, the gauge itself or a connection within the insturment cluster is faulty. Good luck.

I replaced the sending unit to the gauge, grounded it, it read max H. I'm not to sure what else it could be
 






I replaced the sending unit to the gauge, grounded it, it read max H. I'm not to sure what else it could be

If you grounded the gauge wire and the gauge went to max H, then the gauge and the wire are OK. The only thiing left is the sensor unit. Try this - with everything plugged in and the truck at normal operating temp, see if you can find a metal part on the sending unit body and temporarily attach a ground wire to it. If the problem is that the sending unit is not picking up its ground thru the thermostat housing, this should allow the gauge to react normally.
 






did you replace the thermostat?

I had the same problem on a 96. Engine heats and heater works, but gauge is pegged at cold. Simple replacement of the thermostat fixed it for me. Easy DIY.
 






if the gauge went to HIGH when the wire was grounded, then the gauge and wire are OK. did you put teflon tape on the threads of the new temp sender? if so, it might not work because it can't make a ground connection to the block. try connecting a jumper cable to the outside of the sender and connect it to the NEG battery post. if the gauge works then it wasn't able to ground. if it doesn't, it can only mean the sender is no good or your thermostat is stuck open. there's no other explaination.
 






sounds like a stuck open thermostat.
 






well the thermostat that my dad swore was fine turned out to be the culprit, replaced it today and everything works fine
 






Okay, I'm having trouble following here.

My '97 Limited has done the same thing for 2 years. I posted the issue in this Forum earlier this year, but didn't see this thread. More than one dealer has worked on the cooling and air conditioning system in that 2 year period, and the thermostat was replaced to no avail. My service advisor says the likely culprit is buried down where it will cost more labor and parts money than the gauge fix is worth. He claims the thermosensor is fine.

I'd like to see if I can follow your guidance here, but I have no clue where to look for the parts in question. Does the ECM (2 wires) and gauge (1 red/white wire) feed off the same sensor, or are there two sensors, one for the ECM that may be okay and one for the gauge that may be bad?

I grew up in the '50's and cut my teeth on a farm tractor and 50's and 60's cars that were significantly simpler. When Thermactor tubes came along in 1970, things started to get unnecessarily complicated and crowded under the hood. I gave up and in the late 1980's relegated most engine repairs on new cars I bought after that to dealerships that knew the more complex engines. I have only a guesstimate idea of where to look for the sensors mentioned, or what they look like.

Can you fellows describe the sensor(s) and where to find them so I can run the grounding tests you suggested?

Thanks,
hafcanadian
 






There are two separate sensors; both are in the thermostat housing in the top of the engine. Would help to know which engine you have. Good luck.
 






The engine is the 4.0L SOHC V6. 86000 miles.

I'll look for the sensors and see what I can determine testing for ground.
 






I had a similar issue although my gauge would read high (would read about 1/3 when completely cold, and would hit "H" when warmed up and set off the CHECK GAGE light). It was really annoying. Replaced the temperature sender (the sender drives the gauge, the sensor feeds the ECM) with no change.

I replaced the gauge assembly with the coolant and fuel gauges. No fix. I had to replace the ENTIRE gauge cluster to fix the problem. The driving circuit for the temperature gauge must be on the main circuit board.

In case anyone has to do this like I did - I found that the early clusters had a different arrangement of idiot lights and looked slightly different, but are electrically compatible. Just note that sometime in 1997 the backlighting changed from teal to green.
 






I'm having a somewhat similar issue with my 2000 Mountaineer. I've lurked around this site for a while now to read up on repairs but now I'm stuck and hopefully somebody has an idea to throw my way.

My temp gauge was barely over C and my heat was warm, but not hot. Last weekend I changed my thermostat thinking that may be the culprit. The next day the temp gauge was ALL the way down and check engine light came on. A scan indicated that the coolant temperature sensor was bad. Problem solved right?

Unfortunately after replacing the sensor my temp gauge is still bottomed out, and heat in the cabin is basically nonexistent.

Could it be that my new thermostat is stuck open? I'm at a loss here, any advice would be very much appreciated!
 






If the thermostat was new and is good... maybe you install the thermostat backwards?
 






what degree thermostat did you install? sounds like it's stuck open. as far as how you installed it, the pointy end always goes up/out towards the radiator. drain the rad into a clean pail so you can save the new antifreeze you put in it and pull the thermostat and check.

you don't say what engine you have. if it's the SOHC 4.0L, they tend to get air trapped at the top of the engine after draining the cooling system. this will cause the temp gauge not to register off COLD and for you to not get heat as there's no water flow. have you driven the truck or just idled it in the driveway? driving it a SHORT distance will usually "burp" the air out, but it will very quickly then overheat. bring coolant with you and if it starts to overheat, pull over and wait for it to cool down before adding coolant.
 






If the thermostat was new and is good... maybe you install the thermostat backwards?

Lol I'm no certified mechanic but I'm sure it's not backwards.
 






what degree thermostat did you install? sounds like it's stuck open. as far as how you installed it, the pointy end always goes up/out towards the radiator. drain the rad into a clean pail so you can save the new antifreeze you put in it and pull the thermostat and check.

you don't say what engine you have. if it's the SOHC 4.0L, they tend to get air trapped at the top of the engine after draining the cooling system. this will cause the temp gauge not to register off COLD and for you to not get heat as there's no water flow. have you driven the truck or just idled it in the driveway? driving it a SHORT distance will usually "burp" the air out, but it will very quickly then overheat. bring coolant with you and if it starts to overheat, pull over and wait for it to cool down before adding coolant.

It's a 5.0 V8. When I first changed it I let it idle for 5-10 minutes with the radiator cap open and watched for bubbles. I added a little coolant as the level dropped and waited for it to stop bubbling. I then drove roughly 10 miles at 45 mph or so with coolant on hand just in case. Sucker never did heat up.

Maybe the new thermostat was faulty?
 






It's a 5.0 V8. When I first changed it I let it idle for 5-10 minutes with the radiator cap open and watched for bubbles. I added a little coolant as the level dropped and waited for it to stop bubbling. I then drove roughly 10 miles at 45 mph or so with coolant on hand just in case. Sucker never did heat up.

Maybe the new thermostat was faulty?

sounds like that may be the case. when you installed the new t-stat, did you position the "rattler valve" near the top? I've noticed that he 5.0L t-stat housing seems to have a small relief in its casting, presumably that's for the rattler. it's purpose is to let any air escape, but it you've driven it for 10 miles, it doesn't sound like you have trapped air. I've never had a problem with trapped air on the 5.0L engines.

BTW, I find it much easier/less messy to remove the black plastic lower rad cover when draining the radiator.
 









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Test the new thermostat in hot water with a real thermometer and check when it opens, and if it passes install it. Otherwise get a new one.....These things are well known for failing out of the box.... Even the so called "Good Ones".....
 






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