Guys - I have an issue that I'm sure I can find an answer from someone here since I'm at the end of my ability. My electric fan keeps coming on after about 15 mins of use or extended idol (which i expect). The problem is that the temp guage inside reads normal and the clutch fan is operational...with no AC on (it's been only 72 degrees outside) why is the electric fan even coming on? The coolant is good and relatively new....pump seems to be moving fluid....fan clutch was just upgraded to "severe duty". I also had a tranny temp light come on a while ago while on an exteded long trip. Any input would be welcomed.....Its crazy that the temp guage is parked right in the middle of the temp range and the fan is coming on. Could the sensor be bad?

 

I don't have a stock e-fan since they didn't add it until 2000, but it could be possible that the coolant temp sensor isn't working properly. I forget what temp it's supposed to come on at too, but it certainly sounds like you've got something fishy going on there. It'd help to know what year and engine your Durango is/has so others that know more about the stock e-fan can help you out better.

 

To me it sounds like your transmission is overheating so the cooling fan is kicking on to cool off the tranny fluid (as these things have split rads, coolant and tranny fluid). I would first check your tranny fluid. It may just be low. But I'm willing to bet your problem lays in the tranny.

 

Sorry guys. In my haste to get my question out I forgot to include the details. I have a 2002 Durango with a 4.7 and a 45RFE transmission. It's interesting you say the tranny since I have thrown a few tranny codes....Torque converter lockup (P0740)and line pressure low (P0867,0868). I checked the torque converter by taping on the brake while driving on the highway and the rpms jumped a bit so I know its engaging and I can feel 5 "shifts". I'm thinking theres a bad sensor. Same for the line pressure low....I just changed fluid and filters (after getting fault codes) and all is topped off.

 

I wouldn't say tranny. You said your temp gauge is dead center? Only time I got to dead center was sitting at a traffic light for five minutes in 100 degree heat without a mechanical fan, just the factory e-fan.

How's your thermostat? Perhaps your radiator is clogged. Or just full of bugs and gunk

 

There was mention of a trans temp light also. Again, being with the split rad, if the tranny is overheating, it's gunna heat up coolant in the heat transfer between cores. The biggest downfall of having dual fluid cooling rads in our trucks. If one fluid is too hot, it's gunna heat up the other in the process. The only possible thing there is that maybe the rad is indeed clogged on the transmission side.

I'm thinking its a bad sensor somewhere in the tranny as well. Which one? Not sure, someone with more knowledge on tranny's will have to chime in on that.

No sense in throwing parts at it based on what I've said. Just giving you a bit of direction.

 

The temp gauge should not be in the middle as that is not normal and is a sign the coolant temp could be around 210 or higher. Should beat 195z by oem standards.

Perform the free fixes first before buying stuff such as power washing your a/c condenser located in front. Make sure the tranny fluids are correct levels, etc

 

Thanks for all the input guys....Ive done the "Free Stuff" already...cleaned the a/c condensor, checked for any leaks, checked for coolant flow etc... I didnt realize that the needle being in the middle of the guage was not normal. It seems like its been there ever since the D was new (I'm the original owner) and its now 179k later! I'm considering putting an external tranny cooler on to bypass the combo cooler. Has anyone done this before? I'm also reading on here that I should have a 180 t-stat instead of the stock 195?

Also, is the electric/aux fan actually controlled by a sensor in the tranny or is it just the temp sensor on the front of the motor?
Lastly, I have thrown a line pressure low P-0868/0867 code before, so you guys might be onto something with the tranny side of the cooler being clogged.

 

Your low line pressure could be a stuck anti-drain back valve in the trans cooling line. I have seen them things toast a few transmissions as they starved it for fluid. I personally removed mine as well as many other users here. Only thing you have to remember once it is removed is to throw it in neutral for a few seconds to get fluid flowing through the system before you take off.

 

I go with no on the 180 stat. , makes it run richer as the computer tries to get to 195 operating temp. I would delete the check valve and put a aux filter in its place, along with the cooler. May save your tranny. It was to late for mine, but it won't happen again.