Transmission oil temperature

[seb001]

93 Caravan, 3.0L, 4 speed auto
I just flushed out the tranny oil (4 litres came out) and added the proper fluid, ATF 3+.

As preventive maintenance, I was thinking of adding an additional cooler. I'm not sure where/if it will fit since my van has A/C on it. Do I place the extra cooler in front of the A/C condenser?

There is a lot of comments about the proper transmission oil temperature. What is it?

After I changed the oil, I went for a drive to bring the engine to normal operating temp, then parked it (engine running). I was trying to figure if the transmission oil enters the rad at the top or the bottom so I touched the fittings on the rad (where the hoses are connected). Ouch! Both of them are extremely hot. Cannot keep fingers on them but the lower one seemed a bit less extreme. The rad water inlet was hot (normal engine temp, 190-195F). The bottom rad hose was also warm but I assume this is because the van is not moving and there is limted cooling (FYI: The cooling system works, the van does not overheat). How hot should the transmission oil line get?

[seb001]

I did not get any comments but I went ahead and I installed a new
cooler. Setup inline with the factory one.
I mounted in the from of the A/C rad. Was fairly easy, had to remove the fan assembly. Enough hose was provided.
The oil leaves the tranny via the right port, enters the factory RAD at the top, out the bottom, into the new rad and back into the transmission in the left port (closeest) to the engine.

As far as oil temp, the dip stick says Hot is 200F.
In the winter, I will put a piece of cardboard to block the new rad to prevent too much cooling. (It get down to -30C up here)

Need to go on the highway for a 45 minute drive to see if the transmission still jumps out of 4th into 3rd. (Or maybe it's overdrive to 4th)

Seb

[GTP Dad]

Heat is the ultimate killer of any transmission and the addition of an aux. cooler is a good idea. Most vans that are equipped from the factory with towing capabilities come with them already installed. You may have put the cooler on too late if the problem does not correct itself as the damage to the 3rd and 4th gear may be too severe to correct. However, it may only be a bad solenoid since the 4 speed is an electronically controlled transmission.