aftermarket transmission cooler

[Schurkey]

In warmer climates like here in Texas, I do the GM method myself. From the trans into the upper radiator port, then from the lower radiator port to the inlet of the auxiliary cooler then back to the trans. This is how both my Express van and Tahoe were factory plumbed.

Yeah...exactly my recommendation, except you're describing the fluid flow backwards.

The hot fluid coming from the trans goes to the inlet of the aux cooler, from the outlet of the aux cooler to the lower rad cooler port, then from the upper rad cooler port back to the inlet port on the trans, where the cooled fluid lubes the geartrain.

Remember that the inlet to the rad cooler is the lower port, and the outlet is the upper port.

 

[L31MaxExpress]

Yeah...exactly my recommendation, except you're describing the fluid flow backwards.

The hot fluid coming from the trans goes to the inlet of the aux cooler, from the outlet of the aux cooler to the lower rad cooler port, then from the upper rad cooler port back to the inlet port on the trans, where the cooled fluid lubes the geartrain.

Remember that the inlet to the rad cooler is the lower port, and the outlet is the upper port.

I am describing the fluid flow how it flows and always has in both my 97 Express and 99 Tahoe. You are the one describing the fluid flow backwards from the way GM shipped both of these trucks. The hot fluid leaving the transmission goes into the upper port of the radiator first. Then comes out of the lower port of the radiator and travels to the auxiliary cooler. Then it leaves the auxiliary cooler and returns to the transmission. It is impossible for the lines to have been installed backwards on the van too as the outlet from the transmission is on the front and the return from the cooler is on the rear. Both of my auxiliary cooler ports face down, on both the Tahoe and the Van. The fluid leaving the stock 4L60E transmission in the Tahoe also went to the upper port on the radiator first, then came out of the lower port on its way to the auxiliary cooler. I have pulled the upper line off both, clamped a hose to them and directed old fluid out of them with the engine running into a waste container, while pouring new fluid into the fill tube to flush the old fluid out of the converter and transmission. Maybe the older ones flow as you described but the Vortec era ones flow as I just described. Top of the radiator is the inlet to the cooler from the transmission and the lower is the outlet to the auxiliary cooler and the auxiliary cooler has both ports facing down. The one closest to the radiator cooler is the inlet and the one closer to the driverside is the outlet back to the transmission. Both my 97 and 99 have always been and still are plumbed radiator then auxiliary cooler.

 

[L31MaxExpress]

They are even described as such in the descriptions for the replacement lines. As you can see the extra long line goes from the driverside of the auxiliary cooler back to the rear port on the 4L80 or 85E and has extra length post the bend down to clear the converter cover and engine oil pan rail.

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This is the shorter line from the front of the transmission to the upper port of the radiator.

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This is the shortest line that connects the lower port of the radiator to the passenger side of the auxiliary cooler.

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[Schurkey]

OK, I have to take your word for it. I have been corrected.

Strange that GM would reduce the efficiency of the in-radiator cooler by having the trans fluid flow the same direction as the engine coolant. The cooler works better when they flow the opposite direction. In general, the "inlet" to the trans cooler is closer to the lower radiator hose, the "outlet" is farther away from the lower rad hose. But not on the Vortec engines, and--I suppose--some others, perhaps.

 

[Wilecoyote]

It's been 10 yrs. and 45,000 miles. I took pics tonight of the set up. It does go through the radiator AND the Haydon. I forgot how I plumbed it but I used the instructions w the Haydon.

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