Automatic Transmission Flat Tow Re-Circulation Pump


Well-Known Member
I will be towing my Goblin with tiny diameter tires and HHR transmission (top speed will be under 120 at redline) so towing at recommended 65 MPH on a stock setup would have me have to tow at 50-55 MPH to keep the trans revs equivalent. I normally drive at 70. Additionally recommendation is that you start the engine ever 300 miles. At times I go 700-800 miles a day and I don't want to bother with starting the Goblin. While I'm pretty sure there is a good margin, I did not want to worry. I decided to build a transmission oil re-circulation system that operates while towing. While at it I added a oil cooler for the transmission.

I added a 12 VDC pump that will get power from the motorhome while traveling. I tapped the AT sump to feed the pump well below the oil line. The pump is a centrifugal unit and it will not pull well so I wanted to insure that the pump was fed. I doubt that it pump much volume but it will be enough to keep some oil lubing the input end of the trans. I added a filter (the sump oil I will pull is not filtered). Then two check valves, one from the my pump and one from the transmission pump. Either of the two lines feed the oil cooler. There was really no need to cool the oil during towing but I figured it would do no harm. Then the feed to the bottom oil line in the transmission. In the transmission this feed what is called "lube 1" which is the front end of the transmission.
Stock Cobalt Diagram:

Stock AT Diagram.jpg

Dan's Diagram:

Dan AT Diagram.jpg

Sump tap, filter and new pump check valve:

Trans Pump 1.jpg

Sump Tap Enlarged and Oil Pump:

Trans Pump 2.jpg

Oil Pump (back view)

Trans Pump 3.jpg
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