6L80 Transmission Cooler 2014-2018, new and ready to install. Fits the 6L80. Ships fast from the USA.
If your 2014-2018 Chevrolet or GMC with the 6L80 six-speed shows high transmission temperatures while towing, climbing grades or idling in traffic, the part to look at is the thermal bypass valve that controls flow to the transmission cooler. This listing is a billet aluminum replacement for that valve, sold for 2014-2018 GM 6L80 applications. It is the cooler-circuit part buyers usually mean when they search for a 6L80 transmission cooler fix, not the radiator-style cooler itself. It also includes a magnetic service plug with an O-ring seal.
On these trucks, fluid leaving the transmission does not go straight to the cooler. It first passes through a thermal bypass valve (TBV) mounted at the cooler lines. When the fluid is cold, the valve keeps it circulating back to the transmission so it warms up quickly. As temperature rises, a wax element opens the valve and sends fluid out to the cooler. GM TechLink states the original valve was fully open at 194 degrees F, and GM later released a lower-temperature valve, stamped "70", that is fully open at 158 degrees F for many 2016-and-later trucks and SUVs. If the element sticks or opens late, hot fluid keeps bypassing the cooler. This billet valve is built to remove that restriction and keep fluid moving to the cooler, and the magnet in the plug catches ferrous debris you can inspect and wipe off at service time.
Heat is what kills the 6L80. Overheated Dexron VI breaks down, and that leads straight to the converter shudder and clutch wear described in our 6L80 common problems and fixes guide.
GM's own overheating checks are simple and only need a scan tool and an infrared thermometer. Drive until the scan tool shows about 190 degrees F. The pan surface should read close to the scan tool value. Then measure the valve and both cooler lines about 6 inches from it. With a healthy system, the return line reads cooler than the line going out. If both cooler lines read below the pan and the valve body reads above the pan, the valve is not opening. If the dash reading is more than 15 degrees F above the pan, suspect the temperature sensor in the TEHCM rather than the cooling circuit. Check that the cooler fins are not blocked before you replace anything. Our 6L80 Escalade common problems article covers how heat and fluid breakdown show up on the SUV versions of this unit.
The listing covers 2014-2018 GM vehicles with the 6L80 six-speed, which includes the Silverado and Sierra 1500 and the Tahoe, Suburban and Yukon of that era. Line connections changed across these years. Billet valves of this style bolt in where the factory lines are held with a plate-and-bolt retainer and are not made for trucks with quick-connect or clip-style line retainers, so look at how your lines attach before ordering. If you are not sure, send us your year and VIN. More parts for this transmission are on the 6L80 collection page.
| Fits | 6L80 2014-2018 |
| Part type | Transmission Cooler |
| Condition | New |
| Brand | OEM |
| Ships | From the USA |
| Warranty | 1-year |
Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
No. It is the thermal bypass valve that decides when fluid goes to the cooler, plus a magnetic service plug. It replaces the factory valve at the cooler lines.
It is listed for 2014-2018 GM vehicles with the 6L80. Your lines must use the plate-and-bolt retainer style, not quick-connect or clip retainers. Send year and VIN if unsure.
Warm the truck to about 190 F on a scan tool and measure with an infrared thermometer. If both cooler lines are cooler than the pan and the valve is hotter than the pan, it is not opening.
A valve built to keep flow going to the cooler can lengthen warm-up in cold weather. That is the tradeoff for steady cooling when towing or in heat.
Dexron VI. Top off and check the level hot at the fill plug, since these transmissions have no dipstick.
