How to Change the Transmission Fluid & Filter on a 2007 GMC Sierra 1500 Z71

by Phillip James

Your transmission fluid and filter are critical to maintaining the good health of your truck's automatic transmission. Without regular fluid and filter changes, the filter will clog, the fluid will become loaded down with contaminants and your transmission will eventually fail in a very expensive and inconvenient manner. Fortunately, you can change these items yourself. GMC recommends you perform a transmission fluid and filter change every 50,000 miles for heavy-duty use or every 100,000 miles for normal use.

Removing Parts

1

Park the truck on a level surface, set the emergency brake and use the jack to raise the a front corner of the truck. You will be crawling underneath the vehicle while it's jacked up, so ensure the jack is seated securely. You can also use portable ramps to raise the front of the truck if you have these. Remember to set the emergency brake.

2

Locate the transmission pan. On the bottom of the engine area you will see two flat rectangular metal pans. The forward one is the oil pan. Just behind it is the transmission pan. It will be located in the middle of the truck, just about between where the front seats are located.

3

Loosen the shift linkage bracket. This bracket is on the driver's side of the transmission, just above the transmission pan. Use the T 40 Torx bit with a 1/4-inch socket and ratchet to remove the rear bolt holding the bracket to the transmission, then loosen the front bolt enough to move the shift linkage out of the way.

4

Remove the transmission pan. Place a catch pan underneath the transmission pan and then use the 3/8-inch ratchet and the appropriately sized socket to remove the bolts that are spaced around the perimeter of the pan. Go slowly and be ready to catch the transmission fluid that will drain from the pan as these bolts are removed. Pull off the old pan gasket (the rubber seal that goes between the pan and the transmission) and clean off the areas the gasket touches. Clean out any debris that may be at the bottom of the pan, then set the cleaned pan aside.

5

Remove the old transmission filter. It's a large black assembly that mounts immediately above the transmission pan. It will work loose with a downward pulling motion coupled with a little bit of twisting. The filter has fluid in it, so be sure to keep your catch pan in place to keep it from spilling.

6

Inspect the transmission filter seal. This is a black rubber seal, accessible now that the filter has been removed. It mounts directly above the filter itself, inside the vertical hole that you disengaged the filter from when you pulled it off. If the seal looks damaged or exceptionally dirty, carefully remove it. If it looks to be in decent condition, you can just leave it in place. If you do remove the seal, be careful not to scratch the walls of the hole into which it fits.

Install New Parts

1

If you removed the transmission filter seal, install the new one from your replacement filter kit. Coat it with transmission fluid, then use a socket to carefully tap it up into position until it stops.

2

Install the new transmission filter. Coat the neck with transmission fluid and then press it into place until it seats.

3

Reinstall the transmission pan. Place the new gasket onto the transmission pan, then mount the pan back in place. Snug each pan bolt by hand before tightening each one with the ratchet and socket. Tighten the bolts in an evenly spaced pattern so that you avoid tightening all the bolts on one side of the pan at the same time. These bolts should be just tight enough to seal the pan, but don't apply too much force to the ratchet or you can strip the bolt threads. About one-half to three-quarters of a turn past snug should do it.

4

Reinstall the shift linkage. Use the T 40 Torx bit to install and tighten the rear mounting bolt before you tighten the front one. Again, don't apply too much force to these bolts or you will strip the threads--just enough to mount everything firmly in place.

5

Lower the jack and add the new transmission fluid. On the 2007 GMC Sierra 1500, the transmission filler tube is under the hood, on the passenger side of the engine. Add 5 qts. of DEXTRON VI automatic transmission fluid. Start the engine and let it idle in park for a few minutes before checking the transmission fluid level. Add the remaining fluid as needed to reach the proper level indicated on the dipstick.

Tips

  • check Replacement transmission filter kits can be purchased at any auto-parts store. You can also dispose of your old transmission fluid and filter at almost any auto-parts store for free.
  • check Keep all sealing surfaces clean; dirt and grit will cause the seals to fail eventually. When in doubt, wipe clean with a rag and some transmission fluid.

Warnings

  • close A vehicle falling off a jack can kill you. Be very careful to use your vehicle jack correctly while performing this work.
  • close Don't perform this work on a hot engine; you run the risk of burning yourself on engine components and hot transmission fluid.
  • close Transmission fluid is a potentially hazardous material; avoid getting any in your mouth or eyes and wash up after you finish the work. Dispose of old fluid and filters properly to protect the environment.

Items you will need

About the Author

Phillip James has worked in the engineering and technology fields since 2002 and began writing in 2004. His work has appeared in his university newspaper, the "Avion," and he has done private technical manual work. He is pursuing a Bachelor of Science in aerospace engineering from Embry-Riddle Aeronautical University and his aviation airframe and powerplant mechanic certification from the Federal Aviation Administration.

Photo Credits

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