With the nice weather arriving I am getting my '05 ready for some R&R activities. I am going to put my camper on the truck and hook up the boat and head out for some fun. I am thinking I want to upgrade my transmission air to oil cooler so that I can keep my tranny temps from getting high as I use the truck. I will be at max GVW on the truck and my GCWR will be about 17k. Last summer driving in the heat I saw tranny temps of 196 degrees F without the camper or the boat in tow. I know it will go up as I load the truck and travel the mountains so I want to build in lots of margin. Of course I can't find a spec on the OEM cooler so I don't know what it's BTU capacity is but I was looking at using a cooler that has thermostatic controlled electric fan. Some of these units have a 34K-40K BTU per hour rating which is supposedly capable of handling a GVW of 30k pounds. I am interested in knowing if anyone has gone this route of upgrading the transmission cooler and what did you end up using and why, and did it work out for you? I would be interested in getting something that wouldn't take a lot of custom fabrication. As an example BD-Power seems to have a unit that matches up to the 48RE fittings and wiring harness etc. http://www.summitracing.com/parts/bdd-1030606-12/overview/ Sure would be interested in any thoughts or inputs on the route I should go.

Personally I would ditch the viscous clutch / fan assembly and install a High cfm electric fan setup before doing a cooler swap. Frees up more HP and flows more air.

the main thing to remember is the construction of a air/oil cooler..

There are three types/designs of coolers.

The main difference of the three is in the ability to cool the fluid.

The tube-and-fin style has a tube that carries the transmission fluid through the cooler. It is also distinguished by its turbulators, which agitate the fluid to get more of it to contact the aluminum in the tube. Aluminum fins are attached to the outside of the tube and, since aluminum dissipates heat quickly, the heat from the fluid is absorbed by the aluminum, moves out to the fins, and is then carried away from the cooler by the air flowing through the fins on the outside of the cooler. This style of cooler works well but is the least efficient type of cooler.

Tube and Fin:

http://www.rockauto.com/getimage/getimage.php?imagekey=819494&imageurl=http%3A%2F%2Fwww.rockauto.com%2Finfo%2FFourSeasons%2F53002.jpg

Plate-and-fin coolers work on the same principle as the tube-and-fin-style coolers but are more efficient. Plate-and-fin coolers force fluid through much smaller plates that, like the tube-and-fin cooler, cause turbulation (or agitation) of the fluid. But fluid in the plate-and-fin style is cooled better before leaving the cooler because the smaller, flatter plates allow more fluid to contact the aluminum surface inside the cooler.

Plate and Fin:

Stacked-plate coolers are the most efficient coolers. They have the same design as the plate-and-fin style, but they have high-flow turbulators for heavy-duty towing or race applications. The stacked-plate design also includes mounting points for mounting the cooler off the ends. The stacked-plate design also uses -AN fittings, which are popular in high-performance and racing applications where the cooler may need to be installed and removed more frequently than in a typical towing setup.

Stacked-plate:

Personally I would ditch the viscous clutch / fan assembly and install a High cfm electric fan setup before doing a cooler swap. Frees up more HP and flows more air.

It may free up some hp, but as far as I know there isn't a single electric setup that moves more air than the OEM fan. Every fan I have seen for our trucks will actually decrease the GCWR of the truck due to lack of cooling. There are lots of threads about such a swap on other forums. So unless you are empty, or near it, all the time the electric fans are not worth the cost.

As an example BD-Power seems to have a unit that matches up to the 48RE fittings and wiring harness etc. http://www.summitracing.com/parts/bdd-1030606-12/overview/ Sure would be interested in any thoughts or inputs on the route I should go.

John, that BD unit is of stacked-plate design, which is best style to use.. However, at the tune of $370, I choked! That unit is also 13" x 16" 3.5". Not sure on the 3Gen, but the 2Gen trucks will NOT accommodate those dimensions in the OE location, nor will it clear the grill if mounted in front of the AC condenser. I have one that is 11x12x3 and had to located it behind the bumper, next to the side support bracket of the bumper. Even there, it's tight. Having said that, I've got about $150 or so, tied up in it all, including fittings. Here's what I got: (Hayden) 226110 Imperial 10" Electric Fan (2.6"D x 11"H x 11.375"W) - $56.29 (Hayden) 243012 Imperial Maxi-Cool XL Transmission cooler (Size: 3/4" x 11" x 11-5/8") - $64.69 (Hayden) 226206 Imperial Thermostatic Fan Control - Preset 185*F - $27.69 The Thermostatic Fan control, however, is a great big P.O.S. Far better options out there. Here's a Hayden PDF that can maybe help you with your BTU sizing and a bunch of other good info.. http://www.haydenauto.com/upload/HaydenAuto/Documents/Cat_Imperial/2007-imperial-trans-oil-coolers.pdf

It may free up some hp, but as far as I know there isn't a single electric setup that moves more air than the OEM fan.

Every fan I have seen for our trucks will actually decrease the GCWR of the truck due to lack of cooling. There are lots of threads about such a swap on other forums.

So unless you are empty, or near it, all the time the electric fans are not worth the cost.

I installed the Flex-o-lite electric fans on my gen 2 truck and in the install directions they specifically point out that there are rated for 20k GCWR and warn you if you pull more than that then do not install.

Well I don't pull anything over that with my gen 2 but I can tell you that with my camper on and coming up the Montana grade into Billlings on a hot August day that the electric fans couldn't do the job. I saw 225 degrees and rising (while only cruising 62mph) and pulled over to let it catch its breath before I could go on.

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John, that BD unit is of stacked-plate design, which is best style to use.. However, at the tune of $370, I choked!

That unit is also 13" x 16" 3.5". Not sure on the 3Gen, but the 2Gen trucks will NOT accommodate those dimensions in the OE location, nor will it clear the grill if mounted in front of the AC condenser. I have one that is 11x12x3 and had to located it behind the bumper, next to the side support bracket of the bumper. Even there, it's tight.

Having said that, I've got about $150 or so, tied up in it all, including fittings.

Here's what I got:

(Hayden) 226110 Imperial 10" Electric Fan (2.6"D x 11"H x 11.375"W) - $56.29

(Hayden) 243012 Imperial Maxi-Cool XL Transmission cooler (Size: 3/4" x 11" x 11-5/8") - $64.69

(Hayden) 226206 Imperial Thermostatic Fan Control - Preset 185*F - $27.69

The Thermostatic Fan control, however, is a great big P.O.S. Far better options out there.

Here's a Hayden PDF that can maybe help you with your BTU sizing and a bunch of other good info..

http://www.haydenauto.com/upload/HaydenAuto/Documents/Cat_Imperial/2007-imperial-trans-oil-coolers.pdf

Thanks, there were more technical details in there than I have found on most of the product websites I have been researching.

Interesting, I have not researched electric fans for several years but thought there were a few that would outflow the oem fans. I do know that front mount fans are worthless versus rear mount fans. I hear nothing but bad reviews from front mount fans as they block air flow and can't push as much air as a rear mount fan actually pulling air.I know a few guys running Horton fan systems but that is even too rich for my blood.:spend:I know 2 guys who hot shot heavy loads for a living one a 12v and one an 06 CR and both run with no fan at all and they both claim better fuel mileage and no difference in temps while running open road no matter the conditions but see warm temps while in trafic or town but don't need to do a lot of this driving.I know of many folks running their rigs as general DDers with no fan at all as well with no issues.I do realize speed is a huge factor along with other things.

Ya, I have heard of similar stories but it sure hasn't worked for me. The flex-o-lite fan assembley replaces the stock shroud and basically blocks off the air flow through the radiator to all but the openings from the dual electric fans. The dual fans don't move quite as much air as the single larger OEM fan but with the larger OEM fan and stock shroud none of the radiator seems to be restricted to any ram air flow. I think that might add to the reduced load capability of electric fans. I have never had any problems with stop and go in town temps but with the camper loaded on hot summer days going up tall hills with the AC on the radiator with electric fans can't keep it cool.When I put the fans on I could tell the difference is cold starts and cold acceleration but I never could see any real mpg benefit from the reduced horsepower.

I rarely hear my fan at speeds above 55, regardless of coolant temp. It's the high load and slow speed stuff that requires a fan.

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About the hottest I ever get is running at or near WOT at 2K rpms pulling a grade at about 70 mph. I can hit 215° but that's as high as I have seen it. I will hit 211-213° in 5th at 2200-2500 on steep grades.

The factory trans cooler on my 03 seems to be almost as big as the radiator dimensionally... it looks like it would be hard to improve on???

The factory trans cooler on my 03 seems to be almost as big as the radiator dimensionally... it looks like it would be hard to improve on???

Sounds like you're looking at the AC condenser. Sent from my SPH-L710 using Tapatalk 2

Sounds like you're looking at the AC condenser. Sent from my SPH-L710 using Tapatalk 2

The AC condensor is out front, and then sandwiched between the intercooler and radiator is a bare aluminum finned cooler that now appears to be plumbed to the power steering pump?? (My bad) I was under the truck awhile back scouting for a good lift pump location, and I noticed the transmission lines are plumbed to a small box looking device behind the FWS and then continue up to the front of the truck. Am I right in assuming this thing behind the FWS is the factory cooler?? Please forgive my ignorance here I`m still learning all the gadgetry equipped on these trucks.

The AC condensor is out front, and then sandwiched between the intercooler and radiator is a bare aluminum finned cooler that now appears to be plumbed to the power steering pump?? (My bad)

I was under the truck awhile back scouting for a good lift pump location, and I noticed the transmission lines are plumbed to a small box looking device behind the FWS and then continue up to the front of the truck.

Am I right in assuming this thing behind the FWS is the factory cooler?? Please forgive my ignorance here I`m still learning all the gadgetry equipped on these trucks.

No that is not a cooler, many call it a cooler but it is actually a heat exchanger, it works both ways the engine coolant can help draw out some of the tranny heat or the coolant can help warm the tranny oil in cold temps.

The oil leaves the heat exchanger and then goes to the cooler up front and returns to the tranny sump from there.