Transmission normal operating temperture

[Larry B.]

Hello ,
I installed a transmission temp gauge and put an oversize cast Aluminum transmission Pan in ...
Doing 65 to 70 cruising The temp gauge does not hit over 125 until I stop and go in city driving then it'll hit around 150 or so ... I have a 2000 Ford van with the 4R70W transmission ... These temps were when towing my 19 1/2 foot boat... anybody care to say what the best operating temperture might be ? I know cooler is better but maybe I,m running too cool... any comments ? by the way outside temps were in the upper 60,s low 70,s Larry B. >>>>>>. Thanks

 

[friendly_jacek]

Hi,
Usually, 175 F is the quoted AT temp. Readings from different locations may not compare easily. Another variable is whether the temp sensor is really sensing the ATF temp. Where did you install your gauge?
I recently installed a B&M temp gauge in the outgoing oil line in my Subaru and it only indicates 100-130 F. I know for sure (IR temp gun) that the line is 165-175 F with no heavy load, 185 F with light towing, and 195 with heavy towing. I measured the temp of the brass fitting with the sensor and it reads only 130 F.
What gives?

 

[unDummy]

Larry, if your worried about excessively cool fluid, get an ATF cooler thermostat. There are several brands out there to choose from.
As long as the fluid warms up enough to evaporate moisture, any temp around 110-180F is good. During TC lockup on the highway, transmissions cool off and is why you are seeing 125F.

Jacek, try a different brand gauge/sensor.....yours might be defective.

Some transmissions are temp sensitive. This means they won't give you overdrive or lockup the TC until fully warm. Others control line pressure and adjust for ATF temp(assumed viscosity). Know your vehicle.

Mocal/derale/hayden/permacool/....make oil/ATF thermostats.