Didnt mean to lecture just wanted to warn you in case you were not used to towing.

Did the temp drop once you locked out the OD?

 

Well, yeah, but I also slowed down some. I was almost home and I wanted to make it without having to stop. Oh, and I didn't consider that to be "lecturing." I value such info from experienced folks as I am indeed not used to towing with this particular truck.........

 

The drop in temp probably had more to do with the increased RPM than slowing down.

 

OK....I finally had time today to work on my truck. I took a garden hose and sprayed through my radiator to remove any trash. I removed the top radiator supports so I could get the hose nozzle between the radiator and the AC condensor, or whatever that thing is. I didn't really notice that much stuff in there. Just a few bugs, leaf fragments, small sticks and whatnot. After putting all that back together, I changed out my fuel filter and I replaced my engine coolant temp sensor. Then I wrapped it all up, put up my tools, and decided to go on a little test drive. I went out to the Interstate and took a little 5 mile jaunt and the returned home. However, I could not tell whether what I had done helped or not because my water temp guage never moved the whole trip. I am sure I got the plug put onto the new sensor, so I have to wonder if the sensor is bad. I guess I will give her a chance to cool off, then go check it out.........

 

Thermostat, Just change it and watch the temp gauge go back to normal

 

Welp, I unplugged the sensor, checked the contacts and plugged it back. Still nothing. How can I check to see if it is good? I have a small ohm meter, but I am not sure how I would check the sensor. Can I check it with it still installed in the truck (hopefully)?

Heaterman, changing out that thermostat is still pretty close to the top of the list I have made of things to do to try and fix my problem. I actually have thought about ordering that hotter thermostat and one of those cool red housings to put it in.........

 

Heaterman is is right-on. Bad thermostat...

 

Check the harness first. The RD/WH harness lead to ground, resistance should be greater than 10,000 ohms. The YE/RD harness lead to ground, resistance should be less than 5 ohms.

With the ECT sensor disconnected and the key on the gauge shuld read cold. Install a (fused 10amp) jumper wire between the two pins and the gauge should go to full hot. If it does, and the gauge does not move with the engine at operating temperature, the ECT sending unit is bad.

 

Considering it worked properly before you replaced the sender, I would think either the sender is defective or they gave you the wrong one. Did you use tape sealant when you installed the sender? If you did it may be insulating the sender from getting a proper ground.

 

The sensor had some kind of red thread sealing compound on it already, so I did not put any tape on it.

The sensor I bought looks just like the one I took off, except on the new one the plastic part is gray and it was black on the old one. The part numbers on the box are DY-961 and F5AZ-12A648-AB.

 

Usually OEM replacement parts are identical to the original. Compare the new part number with the one on the old part. If the connector is the same on both it may be an updated part. The part number of the replacement looks like an old number.

 

I checked my harness and it seems to be fine. Cookie, the resistance numbers I got were in line with what you mentioned, and my guage went to full hot when I used the jumper wire.

I tried to check the sensors with the ohm meter, but I'll admit that I don't know what I was doing there. I did get similar readings between the two contact posts on BOTH sensors, so I have to wonder if maybe the new one just wasn't hooked up fully. I really don't know what else I could do to cause it to have better contact. The locking gizmo on the plug clicks into place and it won't go any farther. I may switch them back tomorrow, or at least take the new one back off so I can get a better look at without having to stand on my head.

I have been thinking a lot about the thermostat. I pretty much decided that would be my next place to examine, but a couple things still bother me. The truck just doesn't exhibit the classic "bad thermostat" signs that I am used to. Of course this is my first PSD, so maybe they behave differently. If it was stuck closed, would the truck not run hot, even just idling? I ran it for over an hour when the outside temp was over 90 with the AC on wide open while my wife was in a meeting, and the guage stayed right where it was supposed to. If the thermostat was stuck open, would I not have trouble getting the truck to heat up at all? I can idle it for 5 minutes or less and the heater will blow hot air. All this is SO confusing to me. I would like to have some of you that think it is the thermostat to tell me why you think that. I am not doubting or contradicting you, I just want to learn all I can about my truck and I want to put this issue to bed once and for all! We have reservations to camp next weekend, so I need to get it straightened out. No way I can tote that 7000# camper until the truck is fixed!

THANKS for taking time to read all this.........

 

I agree, it doesn't act like the thermostat. If the thermostat was bad it would either run hot all of the time or run cold all of the time. Generally when a thermostat fails, it fails totally. Your problem is too restricted to be a thermostat i.e. prolonged highway driving and towing. The enigne is producing more heat than the cooling system can handle. Either a restriction in the air flow, or water flow. IMO

At this point replacing the thermostat might be a good idea, if for no there reason to eliminate it as the cause. I hope I'm wrong and it takes care of you problem.

 

So are you getting a temp. indication with the new sensor or no??

Send me an e-mail containing your e-mail address and I will attempt to send you the diagnostic subroutine from the service manual.

 

Cookie, with the new sensor I am getting no reading at all on the temp guage.

My e-mail addy is

redintrepid9
@
charter.net

By chance do you do the AOL IM thing? Would enjoy a discussion with you or anyone else about all this. My handle there is Red9Intrepid.