GMC Yukon Transmissions: Overview, Problems, Fluids

GMC Yukon, a counterpart of Chevrolet Tahoe, is a full-size SUV from General Motors, offered since 1991. For the 1995 model year, Yukon gained a new, longer 4-door model, slotting in size between the 2-door models. The GMC Yukon, along with the gas-hungry Tahoe, currently serves as a part of General Motors’ full-size SUV family. The 2021 GMC Yukon has a predicted reliability score of 84 out of 100. In this article, we have mentioned different transmissions used in different models of GMC Yukon.

The GMC Yukon was equipped with the 4L60E in early models, the 4L65E in 6.0L models, the 4L80E in Yukon XL 2500 models, the 6-speed 6L80 in later models, and the 6-speed 6L90 in the later model Yukon XL 2500.

Before you select a car, it is significant to have proper knowledge of the different parts a car uses. In this article, we have elaborated things for you to have a proper understanding of transmissions for different models, their problems, and fluids. Transmission prices have also been mentioned in this article to help you get an estimate of how much you will be spending.

What Transmissions has GMC Yukon used?

The GMC Yukon has used the following transmissions:

• 4L60E Transmission (Early Models)
• 4L65E Transmission (6.0L Models)
• 4L80E Transmission (Early Model XL 2500)
• 6L80 Transmission (Later Models)
• 6L90 Transmission (Late Model XL 2500)
• 8L90 Transmission (Later Models)

How Long Does A GMC Yukon Transmission Last?

The overall lifespan of a GMC Yukon transmission largely depends on how well it was maintained. Factory design flaws also factor into this equation, along with how carefully you drive. But on average, we’ve seen the GMC Yukon transmission last for between 130,000-180,000 miles.

A high-quality replacement transmission, however, can last considerably longer if all of the factory design flaws have been addressed and the vehicle has been maintained. When you consider the 200,000+ miles that a GMC can last overall, you really start to see the value of adding a high-quality replacement transmission when the time comes.

How Much Does a GMC Yukon Transmission Cost?

Everyone would want to be familiar with the prices when one needs to change the transmission of one’s car. Prices vary according to your vehicle type and model. Most commonly, prices range from $2500-$3000. Here we have mentioned estimated prices for your GMC Yukon transmissions:

• 4L60-E transmissions costs around $1,795
• 4L80-E transmissions costs around $2,031
• 6L80 transmissions costs around $3,899
• 4L65E transmissions costs around $1,799
• 6L90 transmissions costs around $3,899
• 8L90 transmissions costs around $5,894

How Reliable Is The Transmission On A GMC Yukon?

I’ve had the opportunity to get my hands dirty with a variety of transmissions, and that definitely includes the ones you’ll find under the hood of a GMC Yukon. The reliability of a GMC Yukon transmission can depend largely on the model year and specific trim level, as well as the care taken in maintaining it.

But here’s the quick answer:

Overall, the transmission on almost any year of GMC Yukon could be considered reliable by almost any standard. Older 4L60E/4L65E transmissions can have issues like sunshell gear fractures. The 6L80 in late-2000s models might suffer from delayed shifting due to TCM or valve body problems. The newer 10L80 has occasional torque converter shuddering. Proper maintenance, especially regular fluid changes, significantly enhances longevity.

Let’s start with the 4L60E and 4L65E transmissions that you’ll find in the earlier GMC Yukon models, from the late ’90s through to the mid-2000s. These four-speed automatics are generally reliable, but they’re not without their problems.

The most common issue I’ve seen is the sunshell gear (you might have heard called the beast if you talk to any gear heards), which can fracture and lead to a loss of second gear, reverse, and overdrive. It’s also common to encounter problems with the 3-4 clutch pack wearing out, particularly in instances of hard driving or if the vehicle is often used for towing.

Moving into the late 2000s, the Yukon started featuring the 6L80 transmission, a six-speed automatic. This transmission is overall more robust than its predecessor, but it isn’t bulletproof. Some of these units have been known to experience delayed shifts or even failure to shift, often traced back to issues with the Transmission Control Module (TCM). Valve body problems can also crop up, leading to harsh or erratic shifting.

The newer models from 2018 and onward typically come equipped with the 10L80 ten-speed automatic transmission, a product of joint development between GM and Ford. These transmissions are generally reliable and offer smooth shifting and improved fuel efficiency.

However, a common issue seen in these are torque converter shuddering, which can feel like you’re driving over a rough road. The cause is usually traced back to either contaminated transmission fluid or a malfunctioning torque converter itself.

Speaking of transmission fluid, it’s crucial to use the recommended Dexron-VI fluid for these transmissions. Using the wrong fluid can lead to sub-optimal performance and even damage over time. Regular fluid and filter changes are critical to the longevity of any transmission.

Common GMC Yukon Transmission Problems

4L60E Transmission (Early Models)

The 4L60-E is a transmission that’s good or bad depending on the vehicle that you own. 4L65E transmission problems are as follows:

• Problems with shifting into 3rd gear whereas the car acts like it’s in neutral. The problem here is 3/4th gear clutch pack failure. You’ll need new pistons and a clutch pack to replace this.
• You lost your second or reverse gear. In this case, we’re talking about a broken drive shell that will need to be replaced.
• Problems with shifting into 2nd gear with a possible ‘check-engine light. The problem here is a worn TCC regulator valve that causes the converter clutch to slip.

4L65E Transmission (6.0L Models)

Following are some of the problems one might face with 4L65E transmission.

• One may experience an unusually harsh 1-2 shift
• Loss of reverse, second and fourth gears. The first and third gears will seem to function normally.
• No movement when the transmission is shifted into Drive or the 3rd gear position. It is possible to experience normal operation when the transmission shifted into second, first, or reverse.
• The vehicle might be stuck in third gear, the instrument cluster may not function

4L80E Transmission

The 4L80-E is not a transmission with many problems. However, there are some things that you should look out for. The 4L80E transmission could bring the following issues.

• One might experience irregular shifting-sometimes a throttle position sensor or input/output speed sensor fails on the transmission which causes it to develop erratic shifting.
• Overheating is another symptom that can sometimes occur (especially when towing heavy loads). The only thing you can do here is to make sure that there’s enough transmission fluid in the transmission. Otherwise, damage may occur to the clutches, seals, and valve body.

6L80 Transmission/6L90 Transmission

Vehicles with 6L80 and 6L90 might face the following issues.

• No forward or reverse engagement or slipping between the gears.
• Vehicles may slip when Reverse is selected or have no/delayed reverse engagement, harsh shifts from 2-3 / 4-5 or slips while in fifth, and slipping acceleration when passing.

8L90 Transmission

8L90 transmissions issues might include:

• Excessively hard or abrupt gear changes.
• One may experience harsh shifts, delayed shifts, unexpected downshift, stuck in a gear, and/or hesitation to shift.
• Drivers may experience a pronounced delay in forward or reverse gear engagement after shifting from Park. This condition typically occurs when the vehicle has been sitting for several hours with the engine off (like overnight).

Differences between Transmissions

The 4L60E is an electronically controlled 4-speed automatic transmission and It weighs 133 pounds without transmission fluid.

The 4L65E is a 4-speed electronically controlled transmission and it weighs 194.6 pounds.

The 4L80E transmission is a 4-speed automatic gearbox that uses similar architecture as the venerable TH400. It weighs around 254 pounds without transmission fluid.

The 6L80 and 6L90 are 6-speed electronically controlled transmissions. Its dry weight is 195 lbs. The only difference between them is the strength of internal components.

8L90 is a General – 8-speed automatic with a traditional torque converter. It weighs 210+ lbs.

Transmission Fluid and GMC Yukon

Transmission fluid is the lubricant for all the moving parts that make up your vehicle’s transmission. Due to the heat generated in the transmission, the fluid can break down over time. What type of transmission fluid you need depends on your vehicle? Your car’s manual provides transmission fluid service requirements. Regular transmission service is necessary to keep your car on the road. The GMC Yukon XL needs to have the transmission fluid and filter changed every 30,000 to 40,000 miles or every two years.

• 4L60-E / 4L80-E/6L80 is compatible with Dexron VI
• 4L65E is compatible with Dexron 3
• 6L90 is compatible with DEXRON VI
• 8L90 is compatible with Dex 6 HP Transmission fluid

Conclusion

The GMC Yukon is a reliable vehicle that doesn’t require anything too fancy and that doesn’t change when you take a closer look at the transmission. You’ll see a lot of overlap between the transmission problems found in the GMC Yukon and other similar-sized vehicles like the Chevy Colorado which has similar problems with it’s 6-speed transmission.

Sources

• https://www.transmissionrepaircostguide.com/gmc-yukon-transmission-problems/
• https://en.wikipedia.org/wiki/Chevrolet_Tahoe
• https://motorandwheels.com/how-long-gmc-yukons-last/
• https://motorandwheels.com/how-long-gmc-yukons-last/#:~:text=On%20average%2C%20the%20GMC%20Yukon,for%20130%2C000%20to%20180%2C000%20miles.
• https://itstillruns.com/change-filter-gmc-yukon-xl-7474297.html