10L80 Transmission Cooler 2021-26

This is the PPE 124068000 bar and plate transmission cooler for the 10L80 ten-speed in 2021-2026 GM full-size SUVs: Chevrolet Tahoe and Suburban, GMC Yukon and Yukon XL, and Cadillac Escalade and Escalade ESV. It replaces the factory stacked-plate cooler. People shop for it when the transmission temperature climbs while towing a camper or boat, when the factory cooler is leaking or damaged, or when a rebuilt 10L80 is going back in and they want more cooling capacity than the truck left the factory with.

What the transmission cooler does in a 10L80

Fluid leaves the 10L80, runs through the cooler lines to a heat exchanger in front of the radiator, and returns to the case. The cooler is not in the loop all the time. GM's bulletin 22-NA-182 explains that on the gas 10-speeds a thermal bypass valve inside the valve body opens at 143 F; below that, fluid skips the cooler so the transmission warms up quickly. On the 3.0L Duramax the valve sits on the frame rail instead and opens at 194 F. Once the valve opens, the cooler is the only thing pulling heat out of the fluid, and its size sets how far the temperature climbs under load.

The PPE unit is an all-aluminum bar and plate core with TIG-welded end tanks and louvered fins. PPE rates the core at 248 cubic inches, about 3.25 times the stock cooler's volume, with 73 percent more frontal area and up to a 45 F drop in fluid temperature. It bolts to the stock mounting points.

Symptoms of a cooling problem on a 10L80

• Transmission temperature reading higher than usual when towing, climbing grades or idling in heat
• Harsh shifts, shudder or flare that get worse as the truck heats up
• Fluid that turns dark or smells burnt before the service interval
• Wet fins, a crusted seam or a drip at the front of the vehicle from the cooler itself
• DTC P27EC on ETRS-equipped vehicles, which GM ties to a twisted cooler line rather than the cooler

How to confirm the cooler is the problem

Rule out the cheap causes first. GM names a twisted cooler line as the cause of harsh shifts, shudder and high fluid temperature on low-mileage 10-speeds; our 10L80 cooler line replacement guide shows what to look for. Then check fluid level hot, at the temperature in your service information. If the lines and level are right and temperatures still run high under load, a larger cooler makes sense. If you have harsh shifts with P0747 or a sudden downshift, read GM 10L80 valve body problems and the recall before buying cooling parts, because a worn valve body will not be fixed by colder fluid.

Fitment

PPE's application list for 124068000 covers 2021-2026 Tahoe, Suburban, Yukon and Yukon XL with the 5.3L, 6.2L or 3.0L Duramax (the 2021 Yukon XL is listed with the 6.2L and 3.0L only), plus Escalade and Escalade ESV with the 6.2L, and with the 3.0L diesel for 2021-2024. One dealer list also adds the 2026 Silverado and Sierra 1500. 2021-2025 Silverado and Sierra 1500 pickups use a different PPE cooler and do not take this one. PPE lists it as replacing GM 84342541 and 85822148, so compare that number on your old cooler, or send us your year and VIN. More 10L80 and 10L90 parts are on the 10L80 parts page.

Install notes

• Plan on about two hours. Work with the engine cold and catch the fluid that drains from the lines.
• Inspect each cooler line as it comes off; replace any line that is kinked, twisted or seeping at the fitting.
• If the old cooler is being replaced after a transmission failure, flush the lines so debris does not go straight into the new core.
• Top off with DEXRON ULV only. GM lists an 8.1 qt service fill for the 10L80, and the larger core holds more than stock, so have a jug of ULV full synthetic ATF on hand.
• Set the level hot with the engine running, then recheck after the first drive and look over both fittings for seepage.
• On the 3.0L Duramax, PPE suggests pairing the cooler with its thermostat bypass valve for the most cooling, since the factory valve stays closed until 194 F.

If the transmission already slips from heat damage, a cooler will not bring burnt clutches back. See 10L80 3-4 clutch failure and the 10L80 friction clutch kit.

Will this cooler fit my 2022 Silverado 1500 with the 10L80?

No. PPE builds 124068000 for the 2021-2026 Tahoe, Suburban, Yukon and Escalade. 2021-2025 Silverado and Sierra 1500 pickups use a different PPE cooler. Send us your VIN if you are unsure.

How much bigger is it than the factory cooler?

PPE rates the core at 248 cubic inches, about 3.25 times the stock cooler volume, with 73 percent more frontal area.

Does it fit the 3.0L Duramax SUVs?

Yes, PPE lists the 3.0L diesel for 2021-2026 Tahoe, Suburban and Yukon and for 2021-2024 Escalade. On the diesel the factory bypass valve opens at 194 F, so PPE suggests adding its thermostat bypass valve.

What fluid do I add after installing it?

DEXRON ULV only. Check the level hot with the engine running, using the temperature in your service information.

Will a bigger cooler fix harsh shifting?

Only if heat is the cause. Harsh shifts with P0747 or a sudden downshift point to valve body wear. A twisted cooler line can also cause harsh shifts and P27EC.

What is included?

One cooler. It bolts to the stock mounting points; inspect your cooler lines and replace any that are damaged.

• 10L80 Cooler Line Replacement Guide
• GM 10L80 Transmission Problems: The Valve Body Wear Behind the Wheel-Lock-Up Recall
• 10L80 3-4 Clutch Failure: Symptoms and Fix
• 10L80 Pressure Control (EPC) Solenoid Symptoms