Can an oil cooler keep the transmission cool in my 2014 Ford Ranger?

I have fitted a new, large transmission oil cooler to my 2014 Ford Ranger Wildtrak. To prevent water from leaking into the transmission from the standard transmission cooling system, can I stop the water at the radiator and rely on the new transmission oil cooler to keep the transmission cool?

Answered by CarsGuide

12 April 2021

David Morley

If you talk to automatic transmission specialists, you’ll soon be told that it’s impossible to over-cool such a gearbox. An aftermarket transmission cooler is designed to work in conjunction with the vehicle’s standard transmission cooling system, so disabling the standard cooler is probably not a great idea.

The problem with coolant entering the transmission is not an unknown one with some Ford (and other manufacturer’s) models and occurs when the standard cooler fails, allowing coolant into the gearbox and destroying the electronics and the gearbox hardware in short order. Unfortunately, this is a design thing rather than a maintenance issue, so the best thing you can do is service the vehicle regularly and make sure that the coolant is changed regularly. Even then, however, swarf from the production process (according to one theory at least) has been known to circulate through the radiator and cause damage to the piping that forms the transmission cooler. A radiator clean and flush might help stave off this process.

If the manufacturer of the aftermarket cooler you’ve fitted can guarantee that the unit will cool at least as effectively as the standard unit on the Ranger, then you might consider disconnecting the standard cooler. Even so, you’d be wise to keep an eye on transmission temperatures, particularly if you tow anything or travel at high speed in high ambient temperatures.

Disclaimer: You acknowledge and agree that all answers are provided as a general guide only and should not be relied upon as bespoke advice. Carsguide is not liable for the accuracy of any information provided in the answers.

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