Transmission Fluid Cooler Flow Test
I did a lot of searching before making my ATF cooling modifications. I found numerous conflicting descriptions of the port purpose. Initially I used the table in the link below but did not have any flow thru my external filter. After that I did the jug test shown in my previous post. After the transmission was fully warmed up the upper port on the transmission produced twice the output of the lower port. So I rerouted my hoses to connect my filter inlet to the top port and have good flow thru the filter.
The table in the following
Cooler Return Line Chart agrees with Maniak's post.
I found the following in my 2000 workshop manual:
Transmission Fluid Cooler Flow Test
1. Remove fluid level indicator from fluid filler tube.
2. Place funnel in fluid filler tube.
3. Raise the vehicle on a hoist, refer to Section 100-02 and place suitable safety stands under the vehicle.
4. Remove the cooler return line (rear fitting) from the fitting on the transmission case.
5. Connect one end of a hose to the cooler return line and route other end of the hose up to a point where it can be inserted into the funnel at the fluid filler tube.
6. Remove the safety stands and lower the vehicle. Insert end of hose into the funnel.
7. Start the engine and run it at idle with the transmission in NEUTRAL position.
8. Once a steady flow of fluid (without air bubbles) is observed, remove the hose from the funnel and
place the hose in a measuring container for 15 seconds. After 15 seconds place the hose back into
the funnel and turn the engine off. Measure the amount of fluid in the container. If adequate flow was observed, approximately 237 ml (8 oz) will be in the measuring container; the test is now complete.
I was thinking the two fittings were vertically aligned but found a drawing of the heat shield in the Workshop manual that shows the external cooler ports. The lower one is perpendicular to the case and the upper one is at a 45 degree angle to the case pointing forward.
Therefore the lower one (rear fitting) is the return port and the upper one (front fitting) is the supply port. I don't know why the cooler flow test uses the return port to route ATF into the funnel.
My advice is to try one way and see if the filter gets warm from the ATF flowing thru it. Mine initially stayed cold indicating no flow so I rerouted hoses.