Need help. Coolant Temperature Gauge always too high!!!

[lilycesar]

I need help with my 1996 Explorer Sport 6cyl 4.0.
The temperature gauge is always on high, even if I just started the engine, the temperature indicator screams upward to the "hot" zone :fire: . So I guess there is something wrong but the temperature. I thought it was the sender, thermostat but after replacing it, the same thing happends. I just flushed the radiator in an effort of helpping any clogs, but nothing...Please I need some ideas. Thank you!!!

 

[MONMIX]

sounds like the sender may have a case of the funk.
Two questions, do you have acess to a decent scan tool, to verify the temp the ECM ( computer ) is seeing.
and do you have the OHV or the SOHC engine ?

 

[pumpkin]

Which one or both?

I thought it was the sender, thermostat but after replacing it, the same thing happends.:

The comma is throwing me off, plus you said replacing it. Which one did you replace or was it the sending unit and thermostat?

From what you described, it sounds like you replaced the thermostat and that won't fix the problem but replacing the sending unit will.....and if that doesn't work, then check out that ECM like MONMIX stated.

 

[lilycesar]

I changed both the sender and thermostat. I took it to Autozone two days ago to have the computer checked but they told me that there are no codes stored. Here is another thing that I don't know if it might have anything to do with this: the temperature control seems not to work. I mean, even if I want to switch to cold air it still blows hot. I checked the dial but seems to be allright. About the engine...how do I know what type is it? Thank you for your help again!!!

 

[lostandconfused]

happened to my 99, we thought it was the guage but the thermostat was actually broken. see if that needs replacing.

 

[budwich]

The gauge system ( I assume you don't have overhead console / message system) uses resistance to "drive" the meter. In your case, if the gauge is going "instantly" to high, this is a sign of a short going to the meter. You probably need to get to your instrument panel and measure the resistance coming in (pin 3 in my 96 reference).... it should be 75 ohms in the cold and shorted / low (5-10ohms) in the hot.

 

[MONMIX]

well it wasnt my intention to look for codes but to figure out what temp the ECM is seeing. Many ( all? ) Explorers have TWO tempurture senders. One goes to the ECM and one to the guage. Since the guage reads too hot at all times, even when you first start the vehicle, we will call that unreliable. I was hoping to see if you can get your hands on a scan tool to find out from the ECM what tempture the truck was really running. That will tell us if you have just a guage problem or a gauge / cooling problem.

 

[BrooklynBay]

You mentioned that you bought the sending unit in AutoZone. They might have given you the wrong part. Try to unplug that sending unit, and see if your gauge drops to zero. Test the sending unit with an ohm meter, or a continuity tester. There are 2 types that are available. One is for a gauge with a variable output, and the other one is for a "dummy" light on the dashboard that only goes on when it's overheating.

 

[chanak80]

I just bought a 95 Explorer and the gauge never moves when running, stays at cold. Shorted the wire and it goes to hot. Resistance of the sensor is about 310 ohms cold. My manual says it should be around 75 ohms cold. I have tried Autozone, Advanced Auto, NAPA and even the Ford dealer and they all try to give me one that measures 310 ohms cold. Anyone know were to find the correct sensor and a possible part number?

 

[BrooklynBay]

If you short it, and it goes up to hot, that means that the lower resistance will raise the gauge, so the higher resistance when it is cold is correct. Measure your sending unit when it is hot. It should be closer to 75 ohms than 310 ohms. If it stays on 310 ohms, then it is bad.

 

[chanak80]

I guess I left out some information, at running temperature it measures right at 70 ohms but the gauge stays at cold. I used a resistor in the 30 ohm range in place of the sensor and the gauge went to mid range. My service manual says the sensor should be 74 ohm when cold and 3.4 ohm when hot. That seems to agree with how my gauge reacts and with what budwich posted earlier in this thread, but I can not find a the sensor that fits that range. The only other possibility I can think of is if there is suppose to be a circuit providing a parallel resistance (say around 95 ohms) that would make the 310 ohms appear as 73 ohms and maybe that circuit is disconnected. As a last resort I may add a resistor in parallel myself. Any help would be greatly appreciated.

 

[budwich]

I do believe you have a connector problem somewhere along the way. As you pointed out, the sensor actually appears to works. When you short the lead, there enough current to "burn thru" any "crud" on the contacts of the electrical path (ie. connector pins) or your short has enough "good contact" at the connector that you are using for your test. This is probably a clue as to where the likely poor contact / connector is. Gets some contact cleaner and give it a try and see if things change.

 

[shylamarsh]

Basically same problem

I need help with my 1996 Explorer Sport 6cyl 4.0.
The temperature gauge is always on high, even if I just started the engine, the temperature indicator screams upward to the "hot" zone :fire: . So I guess there is something wrong but the temperature. I thought it was the sender, thermostat but after replacing it, the same thing happends. I just flushed the radiator in an effort of helpping any clogs, but nothing...Please I need some ideas. Thank you!!!

I have a 98 exp sport that is doing the same thing took it to a local garage and they changed the sensor and let it run for approx. 5 min then opened the radiator cap and the antifreeze they told me was boiling and shot up on the hood and down over the fender on driver side now they are telling me its the head gasket blew /cracked head / or intake valve gasket. I have let it set in their lot for a week now undecided as what to do. not sure if they know what is really wrong with it. Any advice would be appreciated.

 

[budwich]

I would suggest that you do some search in and around here for blown head gasket, hot issues etc..... cause there are a few checks that you can do to help with identifying if it is "probably" a gasket problem... how does it run, oil color, anti-freeze color, smoke color, etc. good luck.

 

[shylamarsh]

1998 explorer sport tempature guage hot!!!

Took my explorer to a different garage, they found the problem and it wasn't the head gasket or cracked heads it was the thermostat. The other garage told me it wasn't the thermostat. It is now fixed and running normal again. So I guess the moral of the story is seek a second opionon before you waste all that money.

 

[budwich]

glad it worked out.... always be wary when they mention "cracked head / head gasket".... yes they go but they should be able to point to specific symptoms and tests that they did to rule out simple stuff before you drop the big $$$.