Our GMC Envoy just surpassed 150k. I spent a couple of hours on a Sunday doing routine maintenance on this vehicle. I performed the 50K maintenance, the 15k maintenance, and the 30k maintenance. The information below shows what is involved with performing the 30k maintenance. It really isn’t much and can be performed easily in your driveway.
The first item to perform is the replacement of the Air Filter. It is located on the passenger side of the truck all the way in the front of the vehicle. You will need to remove the 3 screws that hold the air cleaner box in place and remove the box. You may need to jiggle the box a little bit to get it off but it will come without a lot of force.
The Second Screw is All The Way At The Bottom.
Once the box is removed, replacement of the air filter is very simple. Just remove the old one off the plastic tubing and slide the new one on. Put the air box back together and you’re done with this part of the maintenance.
The next, and last, step in the 30k maintenance is to replace the spark plugs. This is a fairly simple procedure and can be done pretty easily and quickly in your driveway. I used AC Delco original equipment iridium spark plugs for the replacements. The iridium plugs are supposed to last 100k but I never trust that, I would rather do the preventative maintenance. So far it’s working out for me. These plugs should come pre-gapped but I would check them just to be sure. The gap is .043-.045.
To get to the plugs, you will need to remove the plastic air intake hose from the plenum. A flat head screwdriver will be your tool of choice to accomplish this task. Once the clamp is loose, just slide the tube off the plenum and put it aside and out of the way.
Unscrew the clamp and remove from the plastic intake plenum
Loosen the clamp on the other side too; it is attached to the throttle body. This will also require a flat head screwdriver.
There are two 10mm bolts that hold the plenum onto the top of the engine. Remove these two bolts and move the plenum out of the way. This will expose the coil packs on top of the engine.
To get to the spark plugs, you will need to remove the coil packs off of each individual plug. To do this, unbolt the 10mm bolt that keeps the coil packs in place. Once it is out, you can pull the coil pack right off the plug and move it to the side. I never take the electrical connectors off the coil packs because it is easy enough to move it to the side without having to.
Remove the bolt holding the coil pack in place.
Use a 5/8 inch spark plug socket and an socket extension to get the spark plugs out. Remember, lefty loosey righty tighty! You don’t want to over tighten the spark plugs. Remove the plugs and inspect them. You will be looking for any signs of something not working so well. Oil on the contacts, burn marks, etc….. Here is a link to some spark plug issues.
Now you can put the new plugs in. Slide the new plug into the socket and slide it down the hole. Tighten as much as you can by hand to get it started. I would normally tell you ¼ turn passed hand tight but if you can turn it with the ratchet easily you probably need to tighten them some more. I usually tighten spark plugs right up to the point where I will have trouble turning them. You do not want to over tighten them. You just don’t want them coming out!
Reinstall the plenum, don’t forget the EGR tube on the front of the motor, it needs to go on that open port on the top! Put it all back together and you are done!
Don’t forget this hose. It will cause a CEL!