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2009 GMC Duramax Diesel - The Cooling Pans

We Install A PPE Differential Cover and Transmission Pan for Enhanced Cooling and Capacity

Sean Haggai
Dec 29, 2015
Photographers: Sean Haggai
Be it towing or hauling, racing or daily driving, trucks can withstand an ungodly amount of punishment utilizing the stock components. Through the use of basic bolt-ons and diagnostic tuning, owners can literally add power with the turn of the wrench or click of a button. When we began adding power to our 2009 GMC Duramax Diesel, we picked up a ton of additional horsepower and torque to the rear tires over stock with only the Banks Engineering Double-Shot Water-Methanol system. From there, we added even more power thanks to the Banks Engineering Big Hoss kit. With the increase in available power at our fingertips we couldn’t overlook one of the most important aspects of a tow vehicle: a cooler rear differential and transmission. After all, these diesels were meant to last and we’re on a mission to make sure ours lasts a long, long time.
Don’t get us wrong, the factory GM locking differential and 3.73:1 gears were just fine, however, with serious towing duties in the forecast, keeping the differential as cool as possible was of the upmost importance. What’s more, keeping our Allison 6-speed transmission temperatures well below any danger zone was just as critical. While hauling heavy loads, the rear differential and transmission fluids can experience a hellish amount of heat and abuse. Eventually, the oil breaks down viscosity and it loses its ability to lubricate and cool the components. Instead of making your way to the lake or track, you could see your heavy hauler sidelined for repairs.
To keep our daily driver and weekend heavy hauler on the road, we called up Pacific Performance Engineering (PPE), in Fullerton, California for the full treatment to keep our rearend and transmission fluids cool and safe. PPE designs and engineers a plethora of diesel-specific parts and had plenty to offer our Duramax. That said, PPE suggested their Heavy Duty Rear Aluminum Differential Cover (PN 138051010, $349.99) and Deep Aluminum Transmission Pan (PN 128051010, $349.99). Of course, both pieces hold additional fluid over stock but we’ll detail those finer points later on.
Not only are these new PPE components appealing; giving the truck a custom look from behind and underneath but they perform as well. They were a straight win in our book. That said, we headed over to (PPE) for the complete install. While we used a lift for this particular install, we assure you the install can be completed at home in your garage or driveway with basic hand tools. Better yet, we had both the PPE differential cover and transmission oil pan on in a couple hours!
Photo 2/21   |   01 PPE Tranny Pan And Diff Cover
To get things started, Adam Blattenberg began by getting the Duramax safe and secure on the vehicle lift. From there, the removal and install was a breeze. Using a 13mm socket, Blattenberg removed most of the outer bolts that secure the factory differential cover. We left in a few to allow the rearend fluid to drain.
Photo 3/21   |   02 PPE Tranny Pan And Diff Cover
With the factory cover now removed, we could ditch the stock gasket. PPE supplies a new one with the new differential cover. Next, we could begin cleaning up the gasket surface. Using a small piece of Scotch Brite, Blattenberg removed all of the old gasket material.
Photo 4/21   |   03 PPE Tranny Pan And Diff Cover
Compared with the factory cover, PPE’s attention to detail is second to none. These differential covers truly are works of engineered art. Each cover is made in the USA from high-quality cast aluminum for strength and heat dissipation. What’s more, these covers have the largest cooling fins inside as well as on the exterior to maximize cooling. This cover cools and holds extra fluid, which offers thermal stamina on those long hauls.
Photo 5/21   |   04 PPE Tranny Pan And Diff Cover
PPE also adds an exclusive, high-powered Neodymium-magnet-equipped fill plug to collect any metal particles. For hardcore enthusiasts, PPE covets also feature a 1/8-inch and ¼-inch tapped plug for temperature probes. Of course, stainless hardware finishes off each package, which is available in raw, brushed or black.
Photo 6/21   |   05 PPE Tranny Pan And Diff Cover
Using the supplied gasket, Blattenberg lined up the new piece against the PPE differential cover and prepared to install the two against the rearend housing. Notice no gasket silicone or sealer is necessary.
Photo 7/21   |   06 PPE Tranny Pan And Diff Cover
With the supplied Stainless Steel Allen head bolts, we began the process of threading each one into the rearend housing. We finalized the fastening by torqueing the bolts in a star pattern to assure an even load across the pan.
Photo 8/21   |   07 PPE Tranny Pan And Diff Cover
Our new pan now holds an extra quart of rearend fluid. With that in mind, we made sure to fill using 5 quarts of Royal Purple Max Gear 75W-90. Since this Duramax has the locking differential (Option Code G80), we made sure the fluid we were adding had the rearend limited-slip additive. And just like that, our stock rearend had a great, custom look built to last. Extra fluid capacity and fins will surely make this differential run cooler than ever before.
Photo 9/21   |   08 PPE Tranny Pan And Diff Cover
Moving on to the transmission, the install was just as easy. First, we drained all the fluid. Our Duramax was in need of a transmission service including new fluid and filters so we won’t be saving any of this fluid or filters. You shouldn’t either.
Photo 10/21   |   09 PPE Tranny Pan And Diff Cover
Next, Blattenberg removed the factory hardware from the stock pan and dropped it away from the Allison transmission.
Photo 11/21   |   10 PPE Tranny Pan And Diff Cover
Just like the PPE differential cover, the PPE transmission pan is just as fortified and stronger than the stock pan. It’s also completely engineered and cast from A356-T6 aluminum alloy in the USA. It features an all-aluminum construction, complete with the hardware, gasket and internal filter.
Photo 12/21   |   11 PPE Tranny Pan And Diff Cover
Massive cooling fins, both internally and externally help wick away damaging heat. These specific pans also hold an extra 4 quarts of fluid. With the help of the fins and extra fluid, PPE has seen inside operating fluid temperatures reduce by up to 40-degrees. A Neodymium-magnet-equipped drain plug helps contain foreign material out of the transmission internal.
Photo 13/21   |   12 PPE Tranny Pan And Diff Cover
PPE supplies an all-new transmission fluid filter with their Heavy Duty Aluminum Transmission Pan. We installed it just like factory.
Photo 14/21   |   13 PPE Tranny Pan And Diff Cover
A quick wipe of the transmission rail removed any excess fluid or material. From there, we lined up the reusable factory gasket to the aluminum PPE transmission pan and began with new hardware.
Photo 15/21   |   14 PPE Tranny Pan And Diff Cover
PPE supplies a complete set of Stainless Steel Allen-headed hardware for this install. We threaded it into the rail and snugged it down for final.
Photo 16/21   |   15 PPE Tranny Pan And Diff Cover
Unlike most traditional transmissions, the Allison transmission for Duramax Diesel trucks uses two transmission filters – One inside the pan and the other, a spin-on type, which installs on the outside of the transmission. PPE does not supply this filter, though any local parts store should carry it. Blattenberg filled the new outer filter with Royal Purple MAX ATF fluid to prevent a dry start.
Photo 17/21   |   16 PPE Tranny Pan And Diff Cover
Blattenberg noted that some owners forget to remove this critical magnet from the original filter. It’s imperative that this is done and installed on the new filter.
Photo 18/21   |   17 PPE Tranny Pan And Diff Cover
From there, the filter simply spins on hand tight.
Photo 19/21   |   18 PPE Tranny Pan And Diff Cover
With the extra capacity the new PPE transmission fluid pan provides, we used a total of 12 quarts of Royal Purple MAX ATF fluid. We filled the transmission until the dipstick was reading full.
Photo 20/21   |   19 PPE Tranny Pan And Diff Cover
We’ll give the rearend housing a quick coat of semi-gloss black paint eventually but for now, we’re happy to report how many coworkers at the office have commented on how good the differential cover looks, too.
Photo 21/21   |   20 PPE Tranny Pan And Diff Cover
Our PPE differential cover and transmission fluid pan took an afternoon to install. However, we’ll have years of use and peace of mind knowing our differential and transmission fluid is staying cool. It also gave us an opportunity to service the truck at the same time.
Amazon Affiliate links are our attempt to show you real-world pricing and availability for the products we review and install, and while the Amazon links are separate from editorial and advertising, the Truck Trend Network may receive a commission on purchases made through our posts.

Sources

Royal Purple
Porter, TX 77365
888-382-6300
www.royalpurple.com
Pacific Performance Engineering
Fullerton, CA 92831
714-985-4825
www.pacificp.com

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