Last week I finally decided to see for myself how bad the valve coking issue is on my truck, and decide whether I needed do a manual valve cleaning. I took my 2015 Colorado 3.6L CCSB over to my buddy's house (who owns a 2015 Canyon 3.6 CCLB, and a bigger work space), we cracked a few beers and got to work. For the record, my truck had about 39,100 miles at the time of this valve cleaning.
As has been noted before, the engine cover is a little tricky to get off, starting in front of the engine there are two T30 bolts, front and left, and two 8mm hex bolts in the back. I think its easiest to unscrew the flat head screws holding the air box on, loosen the hose clamp attached to the cover and remove the whole air box assembly. With the air box out of the way you can work a long flat head screw driver under the left side of the engine cover and loosen the hose clamp that connects the air hose that's integral to the engine cover to the intake. Remove the airline attached to the cover and an electrical connector and the cover can be pulled off.
There is a pad on the top of the intake manifold secured with two plastic fasteners. Underneath, there are six 13mm hex bolts directly through the top of the intake manifold that must be removed, and two 10mm hex way at the back holding a bracket on that also must be removed (the ratchet is sitting on one in the second picture underneath). There are a few airlines and plugs on the left side that need to be removed, also several plastic one time use fasteners (one not really visible at the back of the intake) securing various wire runs and air lines to the intake manifold... be prepared to break most of the fasteners, they really don't want to come out.
At this point I would highly recommend using compressed air to blow every bit of sand and dust you can away from the intake area, when you lift the intake off, all of that crap can fall into your intake valve ports. Removing the intake manifold will take some finagling with the three 13mm manifold bolts in the rear because they are too long to come all the way out of the top. I had to hold them up a bit while my buddy and I lifted the manifold straight up and off of the nice, reusable manifold gasket, and then shimmied it out. Remove the gasket and set aside. The intake ports should now be visible.
These are the before pictures of my intake valves, starting on the front left (as viewed standing in front of the truck) and zig-zaging to the back.
The valves of four of my cylinders were closed, I taped the other two ports and used compressed air to blow any dust or loose debris out of the uncovered ports. I then sprayed plenty of CRC GDI IVD Intake valve cleaner to the uncovered ports and let them soak for about 20 minutes. Once the coking was loosened up, I used a long flat head screw driver to scrape the worst of the gunk off of the valves. I then used a 12 ga. copper shotgun brush screwed onto one section of a Hoppes gun cleaning rod chocked into a drill to further clean the valves (Note: shotgun brush threads are 5/16x27, and standard gun cleaning rods are 8x32, you either have to use a shotgun specific cleaning rod section, or buy an adapter like I did... $2 at Sportsman's Warehouse).
After cleaning, I stuck a shop vac nozzle into the intake ports, turned it on, and used a thin compressed air nozzle snaked past the shop vac nozzle to blow the remaining liquid and chunks of coking off the valves. All of the left over liquid and coking chunks were sucked up into the shop vac. After all of the closed valves were clean, we taped up those ports, and took the tape off the remaining two ports. We then used a 19mm socket to turn the engine until the two remaining ports were closed and repeated the whole process.
These are the valves in the same order after cleaning.
Everything went back together fine, and the truck cranked right up and ran smoothly.
The valves obviously had some build up, but not nearly as much as I was expecting from reading about issues on the internet. The buddy that helped me clean my valves decided not to bother with his until he swaps spark plugs at the scheduled 100k miles. Had I known their condition, I probably wouldn't have bothered with cleaning my intake valves until 80k - 100k miles either. I can't really say whether the truck feels like it gained any power, if it did, the difference is almost imperceptible.
I have no idea why some of these pictures are showing up rotated... they were correctly oriented on my phone and computer.
As has been noted before, the engine cover is a little tricky to get off, starting in front of the engine there are two T30 bolts, front and left, and two 8mm hex bolts in the back. I think its easiest to unscrew the flat head screws holding the air box on, loosen the hose clamp attached to the cover and remove the whole air box assembly. With the air box out of the way you can work a long flat head screw driver under the left side of the engine cover and loosen the hose clamp that connects the air hose that's integral to the engine cover to the intake. Remove the airline attached to the cover and an electrical connector and the cover can be pulled off.
There is a pad on the top of the intake manifold secured with two plastic fasteners. Underneath, there are six 13mm hex bolts directly through the top of the intake manifold that must be removed, and two 10mm hex way at the back holding a bracket on that also must be removed (the ratchet is sitting on one in the second picture underneath). There are a few airlines and plugs on the left side that need to be removed, also several plastic one time use fasteners (one not really visible at the back of the intake) securing various wire runs and air lines to the intake manifold... be prepared to break most of the fasteners, they really don't want to come out.
At this point I would highly recommend using compressed air to blow every bit of sand and dust you can away from the intake area, when you lift the intake off, all of that crap can fall into your intake valve ports. Removing the intake manifold will take some finagling with the three 13mm manifold bolts in the rear because they are too long to come all the way out of the top. I had to hold them up a bit while my buddy and I lifted the manifold straight up and off of the nice, reusable manifold gasket, and then shimmied it out. Remove the gasket and set aside. The intake ports should now be visible.
These are the before pictures of my intake valves, starting on the front left (as viewed standing in front of the truck) and zig-zaging to the back.
The valves of four of my cylinders were closed, I taped the other two ports and used compressed air to blow any dust or loose debris out of the uncovered ports. I then sprayed plenty of CRC GDI IVD Intake valve cleaner to the uncovered ports and let them soak for about 20 minutes. Once the coking was loosened up, I used a long flat head screw driver to scrape the worst of the gunk off of the valves. I then used a 12 ga. copper shotgun brush screwed onto one section of a Hoppes gun cleaning rod chocked into a drill to further clean the valves (Note: shotgun brush threads are 5/16x27, and standard gun cleaning rods are 8x32, you either have to use a shotgun specific cleaning rod section, or buy an adapter like I did... $2 at Sportsman's Warehouse).
After cleaning, I stuck a shop vac nozzle into the intake ports, turned it on, and used a thin compressed air nozzle snaked past the shop vac nozzle to blow the remaining liquid and chunks of coking off the valves. All of the left over liquid and coking chunks were sucked up into the shop vac. After all of the closed valves were clean, we taped up those ports, and took the tape off the remaining two ports. We then used a 19mm socket to turn the engine until the two remaining ports were closed and repeated the whole process.
These are the valves in the same order after cleaning.
Everything went back together fine, and the truck cranked right up and ran smoothly.
The valves obviously had some build up, but not nearly as much as I was expecting from reading about issues on the internet. The buddy that helped me clean my valves decided not to bother with his until he swaps spark plugs at the scheduled 100k miles. Had I known their condition, I probably wouldn't have bothered with cleaning my intake valves until 80k - 100k miles either. I can't really say whether the truck feels like it gained any power, if it did, the difference is almost imperceptible.
I have no idea why some of these pictures are showing up rotated... they were correctly oriented on my phone and computer.