Where should I hook up my temp gauge on a 1997 E40D trans?

 

In the cooler line leading into the radiator cooler.

 

In the pressure port on the driver's side of the trans, just above the pan. It's towards the front of the trans and has a black hex head plug in it. It has a 1/8" NPT dryseal thread, which is what most senders use.

 

The pressure port is ok but you want to know the temperature of the fluid as it is leaving the transmission.

 

You want to know that, I want to know the temperature of the transmission.

The fluid leaving the trans to the cooler can get REALLY hot. At what temperature do you stop to cool it off? And for how long can you run it at the maximum (whatever temp that is) before you have trouble? I don't know the answers to those questions.

I do know that the max sustained trans temp is about 220°F, and the max for a short time is 245°F, both of those temps are either pan or pressure port. If you are measuring the temps in the trans out line, you can easily go above those if you are towing and the torque converter unlocks. So how hot can you run in the cooler out line?

 

This is the pressure test port right?

 

Wrong my friend.
The fluid leaving the cooler is the hottest it will get.
If you tap into an existing plug you only get what fluid is at that point.
There is no fluid flowing at a pressure port unless a line is added to it.
A guage does not a line make. 99% of the temperature is generated from the convertor.

 

I think you mean the fluid leaving the "transmission" is the hottest it will get. Leaving the cooler would be the coolest the fluid will get. I put my sending unit in the exit line out of the transmission before the fluid gets to the cooler.

 

My mistake. I meant leaving the the transmission before entering the cooler.

 

That's correct.