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Aux trans cooler

LM7Yukon

By LM7Yukon
in Ask A GM Technician

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LM7Yukon Enthusiast

LM7Yukon

Posted
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Does the aux trans cooler on a Yukon have 1 line to the transmission and another to the radiator? How does it differ to not having an aux cooler and using the built in from the radiator?

GM-Tech Senior Enthusiast

GM-Tech

Posted
Posted

Even with the aux. cooler, trans fluid still goes throught the cooler built into the radiator. They don't want the trans to run too cold.

 

Radiator temp usually won't exceed 210-220, whereas under severe conditions (towing, etc.) the trans can easily exceed that. This is where the aux. cooler comes into play.

LM7Yukon Enthusiast

LM7Yukon

Posted
  • Author
Posted
Even with the aux. cooler, trans fluid still goes throught the cooler built into the radiator.  They don't want the trans to run too cold.

 

Radiator temp usually won't exceed 210-220, whereas under severe conditions (towing, etc.) the trans can easily exceed that.  This is where the aux. cooler comes into play.

 

 

 

 

 

Mine didn't come with the aux cooler, so the dealer installed the accessory model which looks like OE, and fits in same place as OE. However, it doesn't appear that the internal radiator cooler is being used anymore, or this isn't connected right.

 

How can i tell?

GM-Tech Senior Enthusiast

GM-Tech

Posted
Posted

One of the lines from the aux. cooler should go to the cooler in the radiator. If they put the GM accessory cooler on, it would require extra effort to hook it up incorrectly. The components come designed to be hooked up the proper way.

LM7Yukon Enthusiast

LM7Yukon

Posted
  • Author
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One of the lines from the aux. cooler should go to the cooler in the radiator.  If they put the GM accessory cooler on, it would require extra effort to hook it up incorrectly. The components come designed to be hooked up the proper way.

 

 

 

 

 

Yes it does. 1 line goes from the aux cooler to the radiator. However, this does not make sense. Isn't the aux cooler supposed to be an independent cooler of the internal? what is air-to-oil mean?

LM7Yukon Enthusiast

LM7Yukon

Posted
  • Author
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I already explained the reasons why.

 

 

 

No you didn't. You said that fluid goes through the internal cooler. I'm refering to the aux cooler which is connected to the inlet of the radiator, which your saying is correct. Thereore, if the aux is connected to the radiator, then how does the internal get used with the transmission?

GM-Tech Senior Enthusiast

GM-Tech

Posted
Posted
No you didn't.

 

From the second post in this thread...

 

"Even with the aux. cooler, trans fluid still goes throught the cooler built into the radiator. They don't want the trans to run too cold.

 

Radiator temp usually won't exceed 210-220, whereas under severe conditions (towing, etc.) the trans can easily exceed that. This is where the aux. cooler comes into play."

 

Read the first paragraph in particular.

LM7Yukon Enthusiast

LM7Yukon

Posted
  • Author
Posted
No you didn't.

 

From the second post in this thread...

 

"Even with the aux. cooler, trans fluid still goes throught the cooler built into the radiator. They don't want the trans to run too cold.

 

Radiator temp usually won't exceed 210-220, whereas under severe conditions (towing, etc.) the trans can easily exceed that. This is where the aux. cooler comes into play."

 

Read the first paragraph in particular.

 

 

 

 

 

But if the aux is connected to the line that connects the radiator to the transmission, then trans fluid is no longer going through the radiator, only the aux cooler.

GM-Tech Senior Enthusiast

GM-Tech

Posted
Posted

Okay, lets see if this works.

 

One line comes out of the trans. This connects to the lower part of the cooler in the radiator. The top line from the radiator cooler comes out and wraps around to enter the aux. cooler. The other line comes out of the aux. cooler and goes back to the trans.

 

Basically, the two coolers are in series. From the trans into one cooler, out of that cooler to the other cooler then back to the trans.

LM7Yukon Enthusiast

LM7Yukon

Posted
  • Author
Posted
Okay, lets see if this works.

 

One line comes out of the trans.  This connects to the lower part of the cooler in the radiator.  The top line from the radiator cooler comes out and wraps around to enter the aux. cooler.  The other line comes out of the aux. cooler and goes back to the trans.

 

Basically, the two coolers are in series.  From the trans into one cooler, out of that cooler to the other cooler then back to the trans.

 

 

 

 

 

Thanks... Now it makes sense.

willfxp Enthusiast

willfxp

Posted
Posted
Even with the aux. cooler, trans fluid still goes throught the cooler built into the radiator.  They don't want the trans to run too cold.

 

Radiator temp usually won't exceed 210-220, whereas under severe conditions (towing, etc.) the trans can easily exceed that.  This is where the aux. cooler comes into play.

 

 

 

 

Quick question.... "They don't want the trans to run too cold"? The transmission fluid l will warm up in the radiator?

 

 

BTW, LM7Yukon, that bold typing wasn't very nice.

GM-Tech Senior Enthusiast

GM-Tech

Posted
Posted
The transmission fluid l will warm up in the radiator?

 

Absolutely. The primary trans cooler is within the tank that contains the engine coolant, which warms up pretty quickly.

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