Coolant temperature sensor relocate, question on thread size.

[AH64ID]

Does anyone know if the coolant temp sender will fit in the port about 8" further aft on the head?

We all know the temperature is higher the closer we get to #6, so I am thinking that port will read temps a few degrees hotter which will make the fan come to life sooner when towing heavy.

I have an 8" extension, and the sensors are cheap enough I plan to just purchase and install a 2nd one for testing reasons. I noticed that the new one has an o-ring pictured, which I didn't think was used with 1/8" NPT which is what that plug appears to be.. but I haven't pulled anything out to verify yet.

Does anyone have any insight?

#ad

 

[mwilson]

Whoa, just re-read your post.

You may have to purchase a female o-ring boss to male pipe adaptor if you want to put it in the head.


Mike.

 

[AH64ID]

I do, and I didn't think of that. Thanks Mike.

 

[AH64ID]

I took a peek at quickserve and couldn't find any of the plugs along the exhaust side, I know the others are 1/2" NPT.

 

[AH64ID]

Looks like it's a M14x1.5, but my extension is long enough to go to one of the 1/2 NPT fittings if I can find a 1/2 NPT to M14x1.5 reducing busing.

 

[seafish]

Looks like it's a M14x1.5, but my extension is long enough to go to one of the 1/2 NPT fittings if I can find a 1/2 NPT to M14x1.5 reducing busing.

It seems like if you are going to move the temp sensor for the reason stated that it would make sense to move it as close as possible to the back of the engine.

Is there any reason you couldn't just cut, splice, solder and shrinkwrap longer wires to go wherever you wanted to put the sensor??

 

[NIsaacs]

but my extension is long enough

Are you talking about an 8" pipe extension? If you are, that will give a false reading, the sensor needs to be in the water flow/movement. Or are you talking about an 8" wire extension?

Nick

 

[mwilson]

I think that he is talking about a wire extension harness.

Mike.

 

[Mikey-KE7LBB]

AH64ID, Have you considered the changes to resistance due to additional length of wire and heat absorption from the extension?? I know that it's like comparing apples to dump trucks, but in the radio world, wire length and resistance values are critical to matching antennas to transceivers.

 

[6speed]

I put a temp sender there for an aftermarket gauge and it works fine. I did leave the origional gauge connected and read the aftermarket install.

 

[AH64ID]

I have a plug and play extension, I doubt resistance is enough to make a difference in that short distance (similar to all the external modules that tap into the line). I also would like to be able to plug into either one to see a difference, if any.

I am going to assume that Cummins tests and knows the temperature differences from #6 to #1 and publishes max allowed temps based on that. Additionally, a higher coolant temp means better combustion and more power from the same fuel so I don't want to effect fan operation most of the time. What I am looking for is those days that I am at 213-215 maybe getting a little more fan. I haven't ever broken 215 while towing, so I am not close to the 225 limit for a 190 thermostat.

I figured a little further aft reading would be good, but I don't want the full hot reading.

I put a temp sender there for an aftermarket gauge and it works fine. I did leave the origional gauge connected and read the aftermarket install.

Do they read different?

 

[rscurtis]

You might want to consider a switch to NPG with its 370* boiling point and not worry about the fan. www.evanscooling.com. You can also run the system at zero pressure.

 

[AH64ID]

The Evans stuff has never interested me, especially on these trucks where you cannot program the fan.

Besides you still have to run a thermostat and heat rejection still has to occur, I am not sure you can ignore the max allowable temps for a specific thermostat based on coolant makeup, those temps are based on the heat rejection of the system. The fan is controlled by the ECM(around a 190 thermostat), and you cannot remove it and still tow. It wouldn't matter if the coolant didn't bill until 1000 deg, you cannot run the motor at much higher ECT, even if it's not boiling. The oil temp would increase, the EGTs would increase, the piston temps would increase and you would melt stuff.

I just don't see how you could not worry about the fan with Evans coolant? Maybe I am missing something.

My current temps are not too high, the coolant boils at 226 at 0psi and 265 at 15 psi. The max allowed for my 190 is 225 so I am good there, and I run 207-215 up steep grades on hot days. A little extra fan operation at 210-215 would be nice for those really warm days of summer, but that's about it.

 

[rscurtis]

I didn't mean to imply that you don't have to worry about the fan. The fan will still operate when necessary, and the thermostat will still be wide open when necessary. You'll simply have an additional 100* safety margin before the coolant starts to boil. Watch the video and see how it is used to improve FE on OTR trucks by running the engine hotter and delaying the operation of the fan.

 

[AH64ID]

I researched it a bit a few months ago, and it's FE increase is based around decreased fan time. There are 2 things that don't really allow that on our trucks. There are not thermostats available higher than 200, and we cannot control the fan. If we could control the fan then it would be worth considering, but as is we cannot even run a 200 thermostat without the fan time increasing.

 

[NIsaacs]

I think that he is talking about a wire extension harness.

Mike.

Yup, never mind me:-laf

I don't know anything about the fan clutch system on a 3rd gen, but is it possible to use a manual override switch? Also, if that is possible, would one fit/work on a 2nd gen?

Nick

 

[AH64ID]

The fan on the 3rd gens is a viscous clutch controlled by the ECM, I'd have to look into it more to see if it's PWM but I am guessing it's.

 

[rscurtis]

Also, if that is possible, would one fit/work on a 2nd gen?

No, the second gen. uses an engine-rotation fan, the third gen. uses a reverse rotation fan. However, Horton did make a clutched fan for the second generation Dodge, I had one on my '95. However, it was strictly on or off, there was no modulation as there is in the third gen. trucks. It responded to coolant temp, high side pressure, or a manual override.

 

[DonFitzwater]

Also, if that is possible, would one fit/work on a 2nd gen?

No, the second gen. uses an engine-rotation fan, the third gen. uses a reverse rotation fan. However, Horton did make a clutched fan for the second generation Dodge, I had one on my '95. However, it was strictly on or off, there was no modulation as there is in the third gen. trucks. It responded to coolant temp, high side pressure, or a manual override.

Unfortunately Horton discontinued this clutch (at least it was no longer available back when I needed one)

 

[rscurtis]

I believe you're correct. It was a lot of dough, too, $700 IIRC.