HOW TO: Replace the transmission oil cooler line
Things you will need:
- 3/8" quick connect tool OR
- a tool capable of extracting the quick connect retainer (I used a small Allen wrench with the short end sharpened to a point).
- A new 3/8" quick connect retaining ring; O'Reilly Auto Parts sells packages of mixed sizes.
- A new transmission oil cooler line. It comes with the seal and the retaining clips. I ordered this from Rock Auto.
- A 13mm socket.
On the transmission side, the procedure is fairly simple. Shown is an image of my 2010 Malibu's 6T40 transmission; your transmission may look different, but the general principle is the same. You remove a nut from the transmission and the line can be extracted with a light force.
In between the transmission and the radiator are two clips. One is a plastic retainer that holds the metal lines to the transmission. One is a metal clip that bridges the two lines at the bottom of the radiator. I didn't take images of these, but they're retaining clips, you should be able to figure out how to release them.
On the radiator side, that's when things get a little more tricky. The quick connect fitting is covered by a plastic ring; this ring simply pulls off the fitting and slides up the line. The quick connect fitting has a retaining ring, and the line has a flare in it that clicks into this retainer but doesn't click back out. To remove, you can use your quick connect tool if you have one, but if you don't, all is not lost! Take your improvised extraction tool; the objective is to pull against one of the open ends of the retaining ring, as if you were rotating the retaining ring in its groove in the fitting. If you succeed, the ring will pop out of position and can be extracted completely with a screwdriver. Removal and installation instructions for the retaining rings can be found here
Shown is a close-up of one of the quick connect fittings; you should be able to make out the groove in which the retaining ring is sitting.
As a side note, on my '10 Malibu, the lower transmission cooler line is difficult to access, but not impossible; all of the above operations can be performed from the top. You might want to practice working tools with your left hand, if you are of the right-handed persuasion. Once both ends of the line are disconnected and the line has been removed from the retainers, extracting it is a matter of manipulating it free from all the electrical connections around the battery box. Installation is the reverse of removal; note that a new retaining ring must be fitted to the quick connect fitting before fitting the line into it, and I highly recommend doing this before even inserting the new line into the engine compartment.
Shown is an image of the old line after it had been removed. You can see the plastic cover for the quick connect fitting on the right and the inter-line bracing clip. The chassis clip I reused. The seal is still on the end that went into the transmission, on the left.