ok, excuse my ignorance, but found something interesting yesterday while working on the Burb. Had the plastic cover off between grill and metal cross support- so you could see front of the radiator. First- I noticed this long skinny, rather rusty, radiator type thing on the drivers side. Pic is here, if it loads. Looks to have one line coming in to the bottom- what is this a cooler for?? Secondly, another small cooler in front of the radiator- about 8x10 " in size- pic here also. Is this second one the trans cooler? Seems awfully small to be the trans cooler on a 3/4 8.1 heavy Suburban. Haven't had any really high temps when towing- and I towed my 18' utility trailer with four pallets of stone the other day. But still, I woulda thought the trans cooler would be bigger. And the other little thing has me stumped.

 

The first pic is power seering cooler. The seccond is an axilary trans cooler.

 

Correct. First is to cool the power steering fluid and the second is the auxillary trans cooler

 

Yeah, auxiliary. That is because the radiator tank has the main (oil to water) trans cooler. That answers why the one you're asking about (oil to air) is so small for a trans cooler.