Thermostat trouble question

[MizzouSport]

I've had by Explorer for a little over a year now and I've noticed that the engine temp guage always seems very low. Recently, it hasn't even been rising more than 1/4 inch above the lowest point. I have plenty of radiator fluid, so I don't think my engine is actually that cold. From what I've read on here, it seems like a lot of people have thermostat trouble. Last night my check engine light came on - could this be related? I'm going to AutoZone tomorrow to run the diagnostic test on it, but does anyone have any ideas? The vehicle seems to be running great with no changes in idling, etc.

 

[Nick26]

The thermostat may be stuck open partially and that is keeping the engine cold. I imagine that its getting colder out too down there in MO, which would explain why lately the engine is heating up less and less as there is more natural cooling going on. I would start with replacing the thermostat because its so cheap and easy to do. I just recently replaced mine which was stuck totally opened so my engine never heated up at all but that did not make my check engine light come on. So either you problem is more involved than mine was or its totally unrelated to the cooling issue. Let us know what the diagnostic checks tells you.

 

[Bored_2wd]

Before replacing the thermostat (it's a little bit of work), or assuming it's bad, check for a loose connection on the sending unit for the dash. My ranger 4.0 engine has two thermostats: 1 large one for the computer and 1 smaller unit for the dash signal. I replaced my thermostat and it had no effect on the dash guage. I then replaced the sensor and still no change. I stopped in to see a buddy of mine who runs a mechanics shop and he said that if I wasn't overheating, my thermostat was fine. He then looked under the hood, removed the wire to the OTHER temperature sending unit, and then put it back on. Instantly the guage started working again.
That was a few days ago. Since then the guage has dropped to the cold point several times. I think it's a loose wire or corrosion. Tonight I'm gonna see if the wire clip-on is just loose on the sender. If it is I'm going to lightly squeeze down on it with pliers to make it hold the sensor tighter. If it seems like the fit is already tight, I'm going to replace the sensor.
Hope this helps!
--Bob

 

[james t]

drive the truck for 10 minutes. turn the heat on all the way hot and wide open. if it blows hot air, then the engine temp is fine and its just the sending unit. if it blows luke warm air then the thermostat is stuck open.

a thermostat can go bad in 2 ways-

1- it will stick closed and overheat the engine

2- it will stick open and the engine will never warm up

usually they stick open when they fail, but not allways

 

[JoeDirt]

Its the thermostat!

I just had my car fail emissions because the t-stat was stuck open which triggered my OBD to send a code.

I replaced the t-stat and now the engine is warmed up in under 5-7 minutes and the needle is between the C and H.

If you're "hot" air is not that hot, then I would say there is a 99% chance that it is your t-stat. I was told at first that it was my water temperature sending unit, but it wasn't.

You can get a stainless steel thermostat for about $10.00. Others will run about $3.00. I think you may need to pull off the belt to replace. Good luck.

 

[MizzouSport]

Just to be sure, do you remember what the specific diagnostic code was in your situation?

 

[MattPersman]

also the distinct possibility the fan clutch is worn out

depends on the rest of the symptoms. if you have hot air come out, then its probably the dash sending unit like others have said. the are a thermosistor (basically means its a heat activated resistor) so any junk or whatever will throw off the reading it puts out. like corrosion on your battery terminals, more resistance, voltage drop.

so go with what the others said and let us know if there are any other problems, questions or comments

 

[JoeDirt]

I had my local service station look at it. I didn't get the code, but it made him believe that it was the water temperature sending unit at first.

Matt....the part we're talking about (thermostat) is actually located along the route of your cooling system...it acts like a dam to regulate the flow of temperature so that your engine is neither too hot or too cold. It is purely a mechanical device (read about it on howstuffworks.com). The sending unit is something different I believe. It is linked inline to the gage that displays the temperature of your coolant (again, just a hunch).

I would replace the thermostat. I was told that my thermostat was busted up in pieces stuck wide open. This sounds like your problem. If you dont already own one, pick up a chiltons repair manual as the job is probably doable with a new tool or two.

Hope this helps.

 

[MizzouSport]

Success!

I went to AutoZone, who said it was my "temp sender," and recommended I change my thermostat, which I did. I found my old one was totally shot, and my check engine light has stayed off since. Thanks for the advice!

Now for my next question...I have a small dead bug between my guages and the plastic covering. It's bugging the CRAP out of me. In addition, I have a light out behind my gas guage. What's the best way to access these areas?

 

[JoeDirt]

Glad to hear it helped

I also have lint and a burned out bulb behind the speedometer. From what I've read, you can't do it without removing the entire dash

 

[Hartman]

I have the same problem. I can drive my truck for 30 minutes and the temp gauge never goes more than 1/4" away from the C. I thought maybe it was the temp sender but I tried to turn on my heat yesterday after driving for 45 minutes and it was only warm. I guess I have to change out my t-stat.

 

[aldive]

Same thing happened to me' changed the gauge and the problem resolved.

 

[Nick26]

Re: Success!

Originally posted by MizzouSport
Now for my next question...I have a small dead bug between my guages and the plastic covering. It's bugging the CRAP out of me. In addition, I have a light out behind my gas guage. What's the best way to access these areas?

when i replaced a bulb i didn't have to remove the upper part of the dashboard, just start pulling out screws starting with the steering column and the ones on the upperside of the guages