The GMT800 generation of General Motors’ fullsize trucks and SUVs is one of the most popular among truck enthusiasts—and for good reason. They’re thoroughly modern vehicles, but still relatively easy to work on, and were the first models to utilize the LS-type V-8 engines. It was also the first generation of GM’s lovable oddball, the Avalanche. However, GM made some interesting choices with the standard configurations, some not always favorable to owners. One of which was the lack of a proper factory transmission cooler for Avalanche 1500 models.
The standard setup for the 1500 model was an integrated transmission cooler/warmer that runs the transmission cooler through a side tank on the radiator to get it to its optimum operating temperature and provide a nominal amount of cooling. This setup is fine if you never tow or put a significant payload in your truck. However, if you plan on towing, sticking with the stock setup can put you perilously close to the danger zone when towing a load, especially with an older, higher-mileage vehicle.
In online forums, there are plenty of horror stories about premature failure of the 4L60E transmission. Most are related to excessive heat or owners tuning their engines to produce more power than the factory transmissions were designed for. Since we’re not planning on doing major engine upgrades that will push the trans beyond its limits, we decided to install a B&M SuperCooler transmission cooler to give us an extra measure of confidence when towing. We selected the model #70264, which has a 14,400 Btu rating.
| The B&M SuperCooler kit comes with most of the fittings and lines you’ll need to complete the installation. Since it’s a universal kit, you may need to purchase additional hardware or fittings to fit your particular application.
To simplify installation and retain the factory pre-heating function, we installed the cooler in series with the factory side tank. This gives us the best of both worlds, because it is able to warm the trans fluid to optimal temperature while shedding excess heat when under load.
We found the cooler made a significant difference in terms of cooling and preventing heat soak. Previously, we could get the transmission fluid to spike to 190 degrees or more with just a few wide-open-throttle runs, or on prolonged uphill grades. Afterward, we made repeated WOT runs and went up a steep, prolonged grade at full throttle, and the transmission fluid temperature remained steady at 150 to 160 degrees. A difference of 20 to 30 degrees can mean the difference between transmission failure or making it to your destination safe and sound when towing. Follow along as we knock out this install in just a couple of hours.
| The first step is to remove the grille to allow easy access to the A-shaped hoop where we’re going to mount the cooler. We loosened and set aside the headlamp housings to allow for easier removal.
| Next, carefully remove the plastic rivet tabs holding the top shroud in place.
| Finally, carefully locate the grille mounting tabs and gently pry them out. The grille should come out easily at this point.
| Now that we have full access to the front of the truck, we can survey our mounting options. The most logical choice seemed to be to mount the cooler on the horizontal crossmember of the A-shaped hoop.
| We placed the cooler on the horizontal crossmember to get an idea of the placement and marked the member with a metal punch.
| To drill the holes on the crossmember, we removed it from the A-hoop.
| That still left the issue of how to brace the top of the cooler. B&M provides a few mounting brace pieces with the kit, along with some mounting bolts.
| We considered just screwing a sheetmetal screw into the A-hoop, but we wanted a more permanent, professional-looking solution. The issue is the hoop is very close to the A/C condenser, and drilling through that would be hundreds more in extra costs.
| To prevent damage to the condenser, we placed a piece of plywood behind the hoop, unbolted the top of the hoop, and shimmed it with a piece of 2x4.
| The drill did dig into the plywood slightly, but damage to the condenser was prevented as intended.
| While we still had the hoop shimmed, we inserted the mounting bolt from the back and secured the brace.
| With the crossmember drilled, we remounted it on the A-hoop and secured the final location of the cooler core.
| The next issue was routing the cooler line. The kit came with one 4-foot section of 5/16-inch line. We would need an additional section to complete the installation.
| After going to multiple auto parts stores in the area and striking out with 3/8-inch line, we were finally able to find the needed 5/16-inch line at a NAPA Auto Parts.
| The next step was to figure out the optimal location of the cooler lines. Because of how we mounted the cooler, our only choice was to route them across the top.
| We had some concern about the line chafing against the top of the A-hoop, near the hood latch. To prevent excessive chafing, we bent back the metal near the hose to prevent it from rubbing against a sharp edge.
| As an added precautionary measure, we took a small section of line that we had trimmed off earlier and split it to add some extra protection from chafing.
| In terms of the line routing, we disconnected the “hot” line from the radiator transmission side tank to run through the SuperCooler and then connected it to the transmission return line.
| B&M provided a fitting to connect the line to the side tank. The factory fitting, which needed to be changed out, was stubbornly resisting removal. A little soaking with penetrating oil helped get it loose.
| We then installed the supplied fitting on the end tank.
| B&M also supplied an additional fitting for the return line. But we thought it would actually be more secure to get the line past the ridge on the metal line and secure it with a hose clamp behind the ridge. This eliminated unnecessary fittings, which are additional opportunities for leaks.
| The routing essentially runs the hot fluid through the B&M SuperCooler before returning it to the side tank to return to the transmission. To tidy up the appearance of the installation, we zip-tied the lines together where they mate up to the side tank.