My Temp Guage Does Not Work Just Sits There On Cold Never Moves.
I Have A 90 250 Inline 6 -4.9.
I Plan On Doing A Trouble Code Test To See Whats Up. Also My Check Engine Light Works But Is Not On. I Would Think It Would Come On If Something Like The Temp Sensor Not Working. If Thats What It Is.

 

I know this is a stupid question .... but here goes did you make sure the lead is attached and not corroded on the temp sensor ???

 

Hah Ha No I Should Look Huh Lol

 

I have the same engine...the cooling system may be screwed up. Could be time for a new t-stat, stock, and none other than recommended (I think 195F), a cooling system flush and some new coolant. BTW..the sensor is a real bear to unscrew from the block, it is on the pass side, rear, behind the exhaust, egr crap, and a few other knuckle-cutting pieces of frame.
I bought my 92 used with 40,000 miles on her...the first very cold winter the darn gauge always read on the "C" line, until I flushed out the coolant and replaced the TSTAT. I don't understand the true physics, but the engine always seems to run cold, and many people have a hard time heating the cab on a real cold day, and some snowy days, its almost impossible to defrost the windshield.

I guess stuck open T-stat

 

i flushed the cooling system a few days ago and no luck with the gauge. is there any way of testing if the t stat is stuck open? i do know that the radiator hose does get hot which tells me that fluid is going in the engine. wouldnt the temp gauge still read soem type of temp. the gauge does not move at all.

thanks for all your help.

 

I had that same problem on my ´89 4.9l and I got it fixed when i changed my temp sensor. It´s a cheap fix,you should try it.

 

Your temp sensor is the likely suspect. They are pretty inexpensive to buy from your local parts house. After 15 years or so they just seem to wear out - mine crapped out in the same manner as yours. I put in a new one and all was good. I have the V8 and the replacement was a piece of cake to do. It sounds like it is not quite so simple on your I6. Good luck to you and waer some Mechanics gloves or something along those lines to save your knuckles.

Cheers!

Mike

 

i might be wrong but isint the temp sensor located on the passenger side on the front top of the motor.? thanks for all you your help. you guys have been a big help

 

The EEC Computer does not even know that engine Temp Sender/Gauge exist, so you would never get a Check Engine Light if it works or not.
The temp sender (not sensor) will have one wire pushed on to it.
Here is a diagram of the location.
http://i54.photobucket.com/albums/g9...Sender6Cyl.gif

 

Thanks For The Diagram. I Just Got A Haynes Manual And It Said Also It Was Located On The Rear Of The Motor. Ill End Up Trying To Fix The Wrong Thing Lol.

But Anyway I Dont Know What Happened But My Guage Seems To Be Working Now. I Let The Truck Run For About 30 Mins. The Temp Guage Reads Right At The Begining Of The Line That Says Normal.

Now Should It Sit Some Where In The Center Of The Guage?? Im Thinking I Have A Stuck Open T Stat...? Let Me Know Hwat You Guys Think Cause Im Going To Go Off Of What You All Think On The T Stat.

Thanks For All The Help.

 

As long as it is inside the normal it is OK as long as you are using a T stat is of the temp the truck calls for. If run with one cooler you will have a problem with engine wear and high fuel consumption.

 

replace only with a 195 deg. thermostat.

also to all of you guys telling this person to just replace the sending unit. that is not nice and it is not what this fourm is about. first check the sending unit with a VOM according to Haynes or any other manual and only if it shows bad replace it. if you tell peple to just start changing parts until it works then you dont even rate as a shade tree mechanic and shuld not be giving advice here.

sorry that is just how I feel . end of rant

 

Best way to test the T-Stat is use the wifes candy themometer.
Drop the T-Stat in a pot of water bring the water to a boil slowly as you keep an eye on the thermometer. Of course if its stuck open that will be obvious. The natural postion (cooled) will be completly closed, as it heats up to its operating temp. it will begin to open and open fully til water passes through the radiator, to cool, returns to the motor, exits by way of the T-Stat (opening or closing as required by the water temp)
Testing the temp sensor (sending unit) is done by using a mutlimeter placing the lead of the meter on the wires from the sensor. The multimeter should be placed in the ohms postion, As the tempature increases the ohm value will increase. There are minimum maximum resitance values with th sensor is not to exceed. There will also be a tempature at which the sensor will have a certain value and as with most these will have a -/+ % tolerance.

 

I just want to say the sender is tough to remove. It may be seized in the block, the area you need to work in is tight,. protect your hands and eyes if under the truck. Of course, you'll need to bleed off some coolant before sender removal.
Make sure you try and troubleshoot first...the 4.9L is notorius for running cool.

 

If you get a new thermostat, go to Ford and pay the extra dollar for the 197 degree thermostat that these trucks call for. I installed 3 195 degree thermostat's from Auto Zone and Advance and the engine would heat up to almost 200, then the thermostat would open and it would run at 189-190 constant. I put the 197 degree one in and it runs at no lower than 196 and now I'm getting better mileage.

I have an aftermarket gauge to determine this. Actually I have two. One is at the factory location for the sending unit in the intake plenum, and the other is in an aftermarket thermostat housing, that way I can moniter how well the thermostat is working. I had an extra gauge sitting around that I was going to put in my Ranger, but figured what the hell...