Adventures in Parts-bin Engineering: The Saturn Vue Transmission Fluid Change

Last week, I noticed a new stain on the driveway in the spot where my wife parks our Saturn Vue Hybrid. A quick sniff test revealed it to be automatic transmission fluid and an inspection of the Vue showed a leak at the transmission pan gasket. The car has just crossed the 100,000 mile mark and the worn gasket decided to accelerate my plans for a transmission fluid change.

Like many modern cars, the transmission dipstick is absent on the Vue, so checking the level is not a quick task. Adding fluid is even more time consuming and requires removal and disassembly of multiple components just to get to the fill plug.

I went out and picked up a filter, gasket, and some ATF and decided to tackle the convoluted process of this transmission fluid change.

Our 2009 Saturn Vue Hybrid uses the ME7 version of General Motors’ 4T45E transmission. The 4T45E is an evolution of the 4T40E, which first debuted in 1995 on J-Body cars such as the Pontiac Sunfire and Chevrolet Cavalier. The 4T45E appeared in the early 2000s on cars like the Oldsmobile Alero and Pontiac Grand Am coupled to the 3.4-liter LA1 motors and others of similar displacement, and was mostly unchanged and used exclusively in cars until the introduction of the Saturn Vue Green Line in 2007. The Green Line necessitated adding an external oil pump along with electronics to work with the hybrid system, but remained much the same internally, sharing its final drive ratio with the Chevy Cobalt.

Much like the hybrid system, the transmission was the product of using existing components from the parts bin along with some engineering patchwork, which resulted in the transmission’s fill and drain locations of our Vue shared with the Alero and others. My first rule of thumb when doing any fluid change is to make sure I can remove the fill plug so I’m not stuck with an empty component, so I looked at the diagram for the 4T45E and started searching for the fill plug.

All other vehicles that use this transmission have some room between their airbox and engine to reach the fill plug, which is on top of the transmission on the engine side. This usually requires snaking your hand in from the front to unscrew the fill, then using a long funnel or hose to extend it to a height where fluid can be poured in. The VUE has no such access due to its height, putting the engine deeper into the bay. Making the task even more difficult, packaging necessitated putting electronics for the engine and hybrid system directly on top of the fill plug.

I started disassembling.

At this point, I have not started the fluid change and am only trying to reach the fill plug as one would if they wanted to add fluid. The process went something like this:

  • Remove the cover for the ECM and Hybrid Electronics
  • Unbolt 10mm that holds the washer fluid fill to ECM plate
  • Unbolt 10mm that holds the positive jump start terminal to ECM Plate
  • Unbolt remaining 7 nuts and bolts that hold the ECM plate to the engine bay
  • Flip the ECM plate over to the engine side to avoid disconnecting the ECM and other electronics
  • The fill plug is now slightly visible but obstructed by the battery; remove battery hold-down
  • Remove battery from the car
  • Remove 4 bolts that hold battery tray in place
  • Realize there’s a fifth bolt under fuse box, loosen the two bolts that hold the fuse box
  • Find a couple swivels and remove the bolt under fuse box
  • Remove (break) snap holding engine harness to battery tray and remove battery tray
  • The fill plug is finally visible, but since the engine and transmission are warm it has expanded and is stuck in the transmission. Find small pliers and loosen the fill plug.
  • This whole process could have been avoided by putting a little thought into the fill location when the engineers decided to grab the transmission from the parts bin. Instead, we’re left with disassembling half the engine bay in order to just add some fluid.

    Once I was sure I could refill the transmission, I put the car on jack stands and started removing the pan to drain the fluid. The fluid actually looked quite red for 100,000 miles, so I knew that the transmission was healthy. I installed a new filter and threw away the thin, rubber gasket that comes with it in favor of a reinforced OEM-style gasket and bolted everything back up. I looked up the fill specs and saw the Vue should take about 7.4 quarts for a drain and fill type of fluid change. I added just over 7 quarts and decided to check the level.

    The level check is a bit simpler than the fill, but is convoluted in its own right. To check the level, the car has to be on level ground and running — normal for many automatic cars — but since there is no dipstick, a check plug has to be removed. Since I did not have the car on a lift and didn’t trust getting an even reading from the car being on jack stands, it had to go back on the ground. I dropped the battery back in and re-assembled the area enough to be able to start the car and run it through the gears. With the car running, I stuck my hand underneath with an 11mm socket and felt for the check plug to remove it. Since no fluid came out, I re-installed the check plug so I could go back up top to add fluid. Failure to reinstall the check plug before shutting the car down would have caused a loss of about 2 quarts of fluid since the pump would be shut off, letting the fluid settle back down.

    This time I decided to add a little over half a quart in order to skip having to add more. I started the car and jumped underneath to remove the check plug again. This time, there was fluid flowing out of it which meant that it was slightly overfilled. I waited until the fluid came to a dribble and put the check plug back in the transmission. I re-assembled all the components on top and took the car out for a successful test drive.

    I’m doubtful the Vue will still be in our possession for another fluid change, but if the process needs to be done again, it will be going on a lift as GM seems to have intended. The only part left of this job is figuring out how to remove the ATF stain in my driveway.

    [Images: © 2017 Bozi Tatarevic, General Motors]

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