I'm Stumped

[Tail_Gunner]

I never did ask...
is it throwing heat?

Yes, it's throwing heat.

After some highway driving, the upper radiator hose is hot, but not so much since I can grab & hold it. The coolant filter however, which taps into the water pump flow prior to the t-stat, is hotter than hell.

I can't work on the truck until after I get back from a couple of appointments today, but I am very ecouraged that my issues will be resolved today.

Yesterday when the OEM temp sensor came, I did a little experiment. I heated some water in the micro wave and took the water and sensor out to the truck. I unplugged the wires going into the coolant sensor and plugged in the new Ford sensor. I then put it into the near boiling cup of water. I got into the truck and turned the key on and watched the temp gauge rise past the cold mark and into the normal range. THIS IS A VERY GOOD SIGN! So all indications are pointing to two bad coolant temp sensors from Advance Auto Parts.

Last evening, I did another little experiment. Again I heated some water, hooked an OHM meter up to the sensor. I then dropped the temp sensor and Mrs TG's cooking thermometer into the hot water. As it cooled, I recorded resistance & temp readings, putting those readings on a sheet of graph paper. I plan on doing the same with the Advance Auto parts sensor when I get it out of the truck. Then I can compare the temp/resistance readings. I am highly confident there will be a big difference. Enough of a difference where I should be able to show it to Advance auto parts and say "This is why it don't work right".

Stay tuned.

 

[BIG JOE]

Sounds promising TG. Standing Bye for NEEWZ (Paul Harvey)

 

[DaveBen]

Very good approach TG. I am willing to make a small bet that the two readings will vary a lot. AA parts are next to junk in my book. I quit using them long ago for anything that does NOT come from a can or bottle (NO BEER).

dAVE

 

[BIG JOE]

Very good approach TG. I am willing to make a small bet that the two readings will vary a lot. AA parts are next to junk in my book. I quit using them long ago for anything that does NOT come from a can or bottle (NO BEER).

dAVE

X2 Dave.

Sometimes ya gota do what ya gota do.. but I try and keep that to minimum, and replace alot of whatevers... ASAP... as best I can.

The "Lifetime" warrenties are nice.. as long as you don't mind replaceing those parts.. time & time again.

 

[Tail_Gunner]

Fixed!!!!!!!!!!!!!!!!

After a lot of head scratching and decuctive reasoning, the temp gauge is working again.

To summarize, when I changed water pumps, I was unable to remove the old coolant temp sensor from the old water pump. After an escalating war with the temp sensor involving bigger & bigger wrenches, I eventually broke the plastic part off the top of the sensor. Off to Adavnce auto parts I went and got a new one. I put it in and the gauge didn't work, so I took it back. They gave me another one which didn't work either. I thought the odds of two sensors not working was unlikely. Assuming the temp gauge to be working, but the engine just not getting up to normal temp., I started looking for other causes, goofey water pump, stuck t-stat, coolant filter, etc. Over the course of several days, I eliminated those other things and was once again looking at the temp sensor as the culprit. I orderd a genuine Ford OEM coolant temp sensor. As I described above, I played with the Ford part with a cup of hot water, a ohm meter and a thermometer, recording resistance/temp readings as I went along.

I installed the Ford sensor today and immedately the temp gauge started working. The only possible remaining issue would be the upper radiator hose maybe being a little cooler than it outta be. But I should be able to fix that with a flow restrictor in the coolant filter line.

One last note before putting this one to bed. I took the Advance auto parts temp sensor that I pulled out today and was going to subject it to the same hot water/ohm meter/thermometer test I did yesterday with the Ford OEM sensor. But I could not get any reading at all with the ohm meter. I got a dead, open short, no connectivity at all. There was no change with hot water or cold water. Sounds like Advance auto parts is going to buy back a second temp sensor tomorrow.

Thanks to all who offered their ideas & suggestions.

 

[BIG JOE]

Done Deal. Glad you got it fixed TG..

Joe

 

[DaveBen]

What a hell of a lota grief over a sensor. Glad you finally got it figured out, Gunner.

Dave

 

[JLDickmon]

and people wonder why labor rates are so high in shops....

 

[Crumm]

Glad you got it figured out

I wonder what years the sensor you got from Ford covers? The one from Advance Auto may be for a broader year range and thus send different resistance values. Regardless I don't think I would stray from OEM sensors in the future.

 

[Tail_Gunner]

The one from Advance Auto may be for a broader year range and thus send different resistance values.

The problem with the Advance Auto sensor was it didn't have any resistance value at all. There was no reading between the two contacts or between either contact and the threads. It was dead as a door nail. I had to double check my meter and verify it was good.