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GMC Forum: 07 Yukon xl Denali trans cooler
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Old 11-29-2017, 02:49 PM
chucks chucks is offline
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Default 07 Yukon xl Denali trans cooler

My transmission lines are leaking going to the cooler. I wanted to replace them with upgraded fittings. My question is do the cooler lines need to run through the radiator or can I get a better cooler and bypass the radiator all together? I don't understand the purpose of running g hem through the radiator if you have a cooler?
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Old 02-12-2018, 12:11 AM
Paul Sebesta Paul Sebesta is offline
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You can bypass the radiator but you need to make SURE that the cooler that you install is sufficient to keep the fluid cool. The reason that the lines run through the radiator and then the cooler is simply that when the vehicle is coming down the assembly line, all of them have lines that go to the radiator. The only difference being that on vehicles with a Towing Package or Heavy Duty Cooling Option (same thing, different names) the lines are added to route the fluid through the auxiliary cooler. The fluid only goes through the transmission auxiliary cooler when the temp of the fluid returning to the trans pan is too high and more cooling is necessary. I hope this helps. Btw, I write service manuals for GM and I am giving you reliable information.
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