transmission temp guage

[TSuter]

In addition to the miriad of other projects planned for this weekend, I'm going to be installing a transmission temp guage. Where is the best spot to put the temp bulb? I've seen where Mad Max "T" into where the existing factory temp bulb, What purpose does the factory bulb serve? Can I just remove it and put my guage bulb in in it's place?



I'm also putting in a aux cooler that will be actuated by a temp bulb. I could "T" in there, but wouldn't the temp at the transmission be a better place to get a more accurate temp?



Sorry for so many questions on one post, but inquiry minds want to know.



TIA



Tom

 

[ANG012]

I have mine T fitting in the line as it comes out of the transmission going to the cooler.

 

[dan brooks]

I did the "T" thing, too.



The factory sending unit is so the transmission will shift out of overdrive once it hits a certain temperature - IIRC, 270-280 degrees... which happens to be hot enough for damage to already have been done. If I were to do it again, I'd just put the sending unit in the stock location and zip-tie the stock sender up and out of the way.

 

[DBF]

The factory sending unit is so the transmission will shift out of overdrive once it hits a certain temperature - IIRC, 270-280 degrees... which happens to be hot enough for damage to already have been done. If I were to do it again, I'd just put the sending unit in the stock location and zip-tie the stock sender up and out of the way.

I'd like to do exactly this, but I want to be sure hanging the switch out in mid-air won't put the trans into limp mode.



In other words, is that switch normally open with cool fluid or normally closed with cool fluid? Anybody know?



It appears to be a 3/8" NPT. True?



Tx, DBF

 

[Greenleaf]

I don't recall. Open... ... . closed..... Monday... . Tuesday... . Wednesday.....



3/8th inch sounds right. See my readers rig pic under "Gauges" I think it is? It's a nice picture of the factory sensor and the "T" fitting instaled in the location of the factory sensor.



The proper part is a "Street T"



I installed it originally in the pan. It seldom moved. I then installed into the fluid line FROM the transmission. Now it moves regular like. Thus, I would assume that the True reading would be the fluid From the transmission and not After it was cooled and returned to the pan?

 

[TSuter]

Went digging through some boxes (just moved) and found my service manuals. The answer to the question of wether the switch is open or closed, is that the switch is normally closed. At least according to the schematic. The switch opens above 278* cutting out the holding voltage to the O/D solenoid.



With that I think I just answered my own question , seeing as the entire circuit is bypassed anyway the factory switch is doing nothing for me installed. Looks like a good place to install the temp bulb for my guage.



Thanks for all your inputs.



Tom

 

[DBF]

Thanks for the info. Out comes the switch, in goes the ISSPRO sender. DBF

 

[mudcat]

I have mine in the pan and it pretty much stays around 150 while running but will climb to the 180 or so if in stop and go traffic. I have considered putting another sender in the line like described above but keep the one in the pan. Then have them both able to read on the same guage different times of course. You could accomplish this with a switch I would think. waht are your thoughts on this? Overkill?

 

[DBF]

I have mine in the pan and it pretty much stays around 150 while running but will climb to the 180 or so if in stop and go traffic. I have considered putting another sender in the line like described above but keep the one in the pan. Then have them both able to read on the same guage different times of course. You could accomplish this with a switch I would think. waht are your thoughts on this? Overkill?

That's what I'm doing, and more. I'll have one on the trans out line, one after the Dodge Superduty cooler/before the second fan cooler, and the one currently in the pan. I eliminated the heat exchanger on the passenger side of the engine.



DBF

 

[BushWakr - RIP]

Keep in mind that when you use the cross-over line (outlet from the TC) you will end up using the typical "T" fitting with compression fittings.

These almost always end up sweating or leaking outright over time.

You can cut and braze/weld in the "T" fitting so it won't leak.

Also, the compression fittings that are used on these will eventually compress the oil tubing and restrict flow... this usually happens when we get frustrated about the leaking/sweating and we get in there an crank down on the fitting/nut.



Just a thought.



pb...

 

[Greenleaf]

You can use the compression fitting. I recieved one from PDR with my gauge and thought it better to use the street T where the factory sensor is located. Maybe I am the only one to think of this? I couldn't see cutting the line to install another fitting when there is already a fitting welded into the line.



Perhaps the line I'm speaking of isn't the same one your refering to PB????

 

[boatpuller]

I disagree with using a t in the factory location, you will get a lower reading than if the sensor is actually in the line, I just removed my factory sensor and replaced it with the gauge sensor and then tie wraped the factory sensor to the line, the only problem with this is that if the ambient air temperature gets over 270 degrees under the truck my overdrive won't engage, I'm guessing at that temperature my overdrive will be the least of my worries.



Caleb

 

[Flexiheep]

I also just replaced the factory sensor with the sensor for the gauge. I have not had any problems in 2 years like this. You better believe that I will be taking corrective action before 270 so its not a worry to me.



As a data point I run 180 most of the time (highway or in town), with time around 200 when climbing steep grades even unloaded. transmission is factory original so it is getting a little soft, if I was driving my truck more I would rebuild with an 89% converter in a heartbeat!