Adding a transmission temp gauge to 700r4

[Ewhitaker0020]

How would I go about adding a temperature gauge for my 700r4 Transmission? It's mostly a curiosity thing. Also what's the safe operating range for my transmission? It's in an 84 K10 with a 305.

 

[1987 GMC Jimmy]

175 or close to it is the gold standard for operating temp. If you go above 200, I’d say that’s too hot. I don’t know how much Dexron viscosity changes from ambient to operating temps, but I know you don’t want a continuously cold transmission either so it has to fight that constantly. If your TCC lockup is working and you’re not pulling anything behind you, you should be right there at that magic number. Unless you tow a lot, I wouldn’t worry about the gauge, and if you do tow, I’d prioritize an external cooler over temp monitoring, but that’s just me. A sender would probably do best in a pressure test port, but you could also tee one into the exit cooling line.

 

[Dutch Rutter]

I added my sender into the test port on the drivers sode of the trans then ran wires to a regular ole water temp gauge which i put in the lower left gauge hole. Works well, isn't the most accurate I think the gauge reads 10 over what the trans actually is. Looks decently factory as well.

I second a good external cooler (plate type not tube and fin), but would also encourage an electric fan to be able to ring in the Temps when things start getting too hot.

 

[Matt69olds]

The best place to put the sender is in the pan. Get a drain plug kit, put the sender in place of the drain plug, it will be the same 1/8 pipe thread. The next best place would probably be the output cooler line, that will read the temp of the fluid leaving the torque converter, that will be the hottest fluid by far. The pressure test port is the worst place, there is no fluid flow. Basically, your reading the temperature of the transmission case. The sending unit needs fluid flowing past it for a accurate reading.

 

[Matt69olds]

As long as you keep the radiator cooler, you really can’t overcool the transmission. The ideal temp is 180ish. Short periods over 225-250 isn’t a big deal. If fluid temp is consistently higher, the fluid cooks and varnishes, clutches glaze and slip, driving the temps higher, which glazed things more, it’s all downhill from there.

 

[SquareRoot]

The ultimate auto trans oil temp solution is an NV4500.

 

[Vbb199]

I for one have been considering a trans temp gauge myself. Good info to know, I had planned on T-ing off of the output line myself.

 

[Ewhitaker0020]

I for one have been considering a trans temp gauge myself. Good info to know, I had planned on T-ing off of the output line myself.

From some research it sounds like the output line from the torque converter is the best place to add a gauge. The pressure port sounds like the easiest, but doesn't sound accurate. I don't need to know my transmission temperature. I rarely tow anything, but I do haul firewood or gravel sometimes and I just want to know what pushes my truck over the line so I can avoid that.

 

[RecklessWOT]

175 or close to it is the gold standard for operating temp. If you go above 200, I’d say that’s too hot. I don’t know how much Dexron viscosity changes from ambient to operating temps, but I know you don’t want a continuously cold transmission either so it has to fight that constantly. If your TCC lockup is working and you’re not pulling anything behind you, you should be right there at that magic number. Unless you tow a lot, I wouldn’t worry about the gauge, and if you do tow, I’d prioritize an external cooler over temp monitoring, but that’s just me. A sender would probably do best in a pressure test port, but you could also tee one into the exit cooling line.

i have an external cooler AND a gauge for my 700R4. When not towing, or driving hard for extended periods of time (literally like a half hour or 45 minutes) under normal use it rarely gets above 120deg

 

[Ewhitaker0020]

i have an external cooler AND a gauge for my 700R4. When not towing, or driving hard for extended periods of time (literally like a half hour or 45 minutes) under normal use it rarely gets above 120deg

Where did you put your sending unit at?

 

[Matt69olds]

The hottest I have ever seen the trans in my Olds get is right at 200. That was in 90* temps, pulling a small U-Haul trailer on drag week in 2015. The curvy hilly road Hot Rod made us take meant 40-45 mph tops, that meant laying on the torque converter pretty hard.

My Cummins powered ram has been as hot as230ish, pulling a heavy trailer, stop-n-go traffic jam, also 90+ degrees. Once traffic started moving it cooled right back down to its normal 170.