Trans. experts: please clear this up for me...

[GoldT]

87 Turbo Regal, 2004r; which cooler line is outlet, which is inlet? I did a search and found that it seems to be a matter of opinion. 50% say the top (frt) is inlet, the other 50% say the bottom (rear) is inlet. I called the shop where I bought my temp. gauge and sender, and the gentleman that answered the phone told me to mount the sender on the front fitting (top). After I get an answer to the initial question, I have a follow-up question about my readings. Thanks in advance.

Jeff

 

[WE4]

Now, This is gospel..

Top is discharge, meaning "out"
Bottom is return, which means "in"

Now what you want to measure is where this comes into play.
We "reccommend" installation in the "return" cooler line so you know what the trans is seeing coming back to it. That is where we measure.

Some try to install it in the pan or the mainline pressure port. By measuring the pressure port temp is basically measuring the case temp as that oil not flowing to a source, is stagnent oil, meaning it just sits there and is pressurized by oil BEHIND it so not accurate.
Pan oil is not that accurate either. that is just what is in the pan and not what temp "working oil" is.
If you want to know what Converter discharge oil; temp is, then the top line is what you want. Cooler oil is a direct discharge from the converter and returns to an open source through center support for lube and eventually "bleeds" back into the pan after lubrication of rotating internals has been accomplished. That is the circuit.

Now ALL other trans in Gm's stable , with the exception of the 4l6oE, has a bottom out top return property about them. So in fact it is "Backwards" of all other gm trannys.
Thats the truth.

Bruce
WE4
PTS XTREME

 

[GoldT]

Thanks, Bruce. That leads to my next question: Since I installed my sender on the top fitting, I am measuring at the hottest point, right? So yesterday, I took my car to get it ASM (emissions) tested. They test at 15mph with a slight load (1st gear, 0 boost), and at 25mph(2nd gear). The ambient temp. was about 82*. They ran both tests twice, without any cooldown time(90 sec. each times 4). The trans. temp. stayed just below 250*. Steady highway cruise results in about 150*. WOT bursts result in 195-200* temps. City driving results in 170-190* temps. I didn't have a gauge when the ambient temps. were in the 100's with the a/c going, but considering that these are being measured before the cooler(aux. cooler as well as the radiator, w/ a dual fan setup), it seems that the temps. should be 30-40* cooler after the cooler. What do you think?

Jeff

 

[WE4]

Yes, I believe you are correct.

Put it in the return line tho....

Bruce
WE4
PTS XTREME