06, Auto, Trans Cooler Connections?

[gsp]

OK,

The Service manual indicates auxiliary transmission coolers should be connected prior to the engine radiator cooler. page 7-228 and 7-229 The flow path is: trans-out>auxiliary cooler>radiator>trans-in.

1. I understand that this will assure the trans fluid will always be at the engine water temperature and the auxiliary cooler will cool down spikes in temp prior to entering the engine radiator.

2. Just don't think this buys much cooling effectiveness but does assure trans operating temp is achieved in the winter.

In the past we always installed the cooler on the return line. The flow path is: trans-out>radiator>auxiliary cooler>trans-in.

1. In this case the trans fluid can achieve temperatures below the engine water temperature.

2. The down side: The trans can run to cold in the winter or take a long time to reach proper operating temperatures.


I have two questions:

1. Does the 4L65 require a minimum temperature to operate properly?

2. Which flow path do yall use and why?

[gsp]

I found this in the service manual: page 7-310

The TCM uses the TFT sensor information to control shift quality and torque converter clutch application.

I have run big fan coolers on my diesel transmissions and have been successful at running between 160-170.

Now running these big fan coolers on the trans return line (The flow path is: trans-out>radiator>auxiliary cooler>trans-in),,, You run the risk of changing the proper operation of the SSR transmission.

Running fluid temps below 210 down to the 160-170 range, we might not be getting good shifts and complete torque converter lock up.

Please answer my two questions on the previous post.

[Mike in AZ]

Remernbering Physics ........ fluid to fluid heat exchangers are significantly more efficient that fluid to air heat exchangers.

I follow the Service Manual philosophy very strongly. Three reasons for that....

1) Cold weather operation as you have noted.

2) The trans cooler is in the coolest part of the radiator. The coolant temperature here is consistently slightly above ambient and provides a consistent temperature of tranny fluid back to the transmission pan.

3) Most significant is that this will extract heat out of the tranny fluid BEFORE it exchanges heat into the engine coolant. This configuration provides the best choice for an engine cooling system that has little or no excess capacity.... like ours.

I'm sure there are others who will have differing opinions, but this is my 2 cents.

Please also note that the tranny fluid is coming from the converter output and is the hottest point in the system. The fluid that returns to the transmission is dumped into the pan. It will be "normalized to the general tranny temp pretty fast.

Regards,

Mike

[gsp]

Thanks,

Good answer!