The transmission cooler lines play an important role in keeping your transmission running smoothly. They help to allow transmission fluid to flow through the cooling system, which prevents overheating and damage to the transmission.
When they’re clogged, leaking, or break, it can cause all sorts of problems with your GMC Envoy .
If you’re noticing problems with your transmission, such as slipping gears, delayed acceleration, or a burning smell, it might be time to change your GMC Envoy’s transmission cooler lines if this is the cause due to low transmission fluid.
The good news is that this is a relatively easy job that most people can do themselves.
Here are the steps you need to take to change the transmission cooler lines on your GMC Envoy :
1. Get the vehicle up in the air with the use of either a jack and jack stands or ramps.
2. Remove the skid plate and the splash guard (if applicable).
3. Disconnect the transmission cooler lines from the transmission. It is best to do this one by one so you know which line goes where. Often times, it may be better to cut the lines to make removal easier
4. Remove the old lines and replace them with new ones.
5. Reconnect the transmission cooler lines and reattach the skid plate and splash guard.
6. Fill your GMC Envoy with the correct fluid to the right level. – Find the correct fluid for your GMC Envoy here.
It’s important to note that there are a few different ways to do this job, so be sure to follow the instructions that came with your new lines.
Also, be careful not to damage any of the other components in the area when you’re working on the transmission cooler lines.
If you’re not comfortable doing this job yourself, then you can always take your truck to a mechanic. But it’s a good idea to know how to change your GMC Envoy’s transmission cooler lines, just in case you ever need to do it yourself.
GMC Envoy Transmission Cooler Line Issues
If you are planning on installing an aftermarket transmission cooler on your GMC Envoy, it is a good idea to check the existing transmission cooler lines prior to installation, especially if your GMC Envoy is older and in an area where rust is problematic.
If you’re installing a transmission cooler you will need to work with your factory transmission cooler lines, so now would be the time to see if your GMC Envoy’s transmission lines are leaking or they will need to be replaced.
It is common that you will find your transmission lines are leaking due to rusting out over time, especially if you live in an area that is more prone to causing your vehicle’s under carriage to rust. Below shows a perfect example of what rusted transmission cooler lines look like.
How To Remove & Replace Transmission Cooler Lines on GMC Envoy.
Replacing the trans cooler lines on yourGMC Envoy is not too hard of a task. The hardest part will be removing the lines from the transmission. These fittings are typically held in by clips that go into fittings, which can make things easier or harder depending on how you choose to remove the lines.
Typically it is easier to remove the clips that hold the metal lines in place rather than messing around with a wrench in a tight space.
How To Remove Transmission Lines From Radiator on GMC Envoy
To remove these lines first peel back the small plastic cover on the fitting and simply use a pick or small screw driver to pop the clips out.
It is always best to have a couple of extra C clips around when removing old ones due to the fact they tend to pop off with force and fly into random places.
GMC Envoy Transmission Cooler Line Diagram & Routing
The design of the transmission cooler lines on most GM vehicles is fairly straight forward. If you have a setup without a transmission cooler from the factory (in most cases this is standard unless you have a truck), you’ll only have 2 transmission cooler lines going to and from the transmission to radiator, the send and return.
If your GMC Envoy does have a factory external cooler, then the return line at the top of the radiator will then go to the front of the truck to the cooler, rather than straight back to the transmission.
This often confused people who aren’t familiar with transmission cooler line orientation, and they confuse the send and return lines.
Below is a basic GMC Envoy transmission cooler line diagram showing the standard hot (send) and cool (return) lines as the flow through a factory cooler setup.