4L60E Auxilliary Cooler Necessary?

[SAATR]

Not really. Water based coolers are far more efficient at heat exchange, hence the reason auto OEM's as well as large truck and heavy equipment manufacturers use water based coolers as the primary heat exchanger for their power trains. Size for size, the liquid units work a lot better than air.

As far as routing goes, making cold fluid even colder is catastrophic failure waiting to happen. A properly designed aux cooler has a differential pressure valve to allow the oil to bypass it when it's too cold. Most aftermarket units don't have this, and the ones that do aren't cheap. Makes more sense to heat the fluid first, and also have a bypass on the aux cooler in case the fluid is still too thick.

Finally, heat exchange is heat exchange. If you have two exchangers plumbed in series, their total cooling capacity doesn't change no matter which way the fluid flows. So what purpose does it serve to reverse them?

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[Ironhead]

OK, here comes my amateur opinion. skip this post if you like, but it seems to me that the trans will operate best if the fluid is at some designated "normal operating temperature'. If the fluid goes to the rad first, then the auxiliary cooler, on a cold day, that fluid could be very cool when it returns to the trans. However, if it goes from the trans to the aux, then to the rad, it will exit the rad at the temp of the coolant in the bottom (return) tank. This would help keep the trans fluid at a more constant temperature, and I have a hunch that that temp is close to what the engineers specified for the best operation of the trans.

 

[Kyle]

Which companies would these be? Every factory aux cooler I have seen has the fluid flowing through the rad first, then to the external cooler. They would have you change the factory flow path to get a warranty?

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Well i thought the same as you SAATR until i took an auto tech class and the way it was explain to me was that if the trans fluid is too cold then itll be thick causing a strain on the pump and other parts in the trans...Nathaniel2g is right.....honestly i still question it. but jasper i believe is one company that requires it this way.

 

[someotherguy]

I'll throw this into the mix, if you're stressing your 4L60E by towing with it, running tall tires without upgrading gears to regain your mechanical advantage, or abusing it in other ways - you'll still find the stock weak links regardless of keeping it cool. This is almost guaranteed. Speaking as someone who has blown up my share of 700R4/4L60/4L60E transmissions, so many I have lost count...and many of them had auxiliary coolers installed. Most recent was my '94 C2500LD, blew the trans at 158K miles, while running a steady 150F on the gauge I added. I was blasting down the highway around 70 MPH with a small utility trailer in tow, nothing on it but my Harley (maybe 500 lbs, bare bones chopper.) The transmission lasted as long as many of them tend to, 100-150K miles. Boom.

Am I saying don't bother with an aux cooler? Nope. Just don't expect it to solve all your problems. If you're going to run those big tires, spend money on gears too. Your transmission will last longer, and the truck will be more fun to drive, too.

Richard