Spark Plug Fun - 2017 GMC Yukon Denali XL

[Darkstar72]

I wanted to share the joy I had swapping out the plugs and wires on my 2017 GMC Yukon Denali this past weekend. I watched multiple YouTube videos to prepare myself and give me a plan of action going forward and boy was I glad I watched a few people do this job. I used every single tip/trick that each person shared in their video on getting the dreaded #8 plug buried behind the a/c lines on the pass side. The drivers side is really straightforward with everything in sight and nothing really special there. Just kept swapping out extensions and swivels depending on which plug I was going for. The fun really starts on the passenger side and this is what I did...first jacked the truck up, took off the pass front wheel, and then removed the wheel well liner. According to some videos this is all you need for access...I still was not having an easy time. I went back up top and pulled the plastic retainer out of the metal bracket off the pass side valve cover for the heater hoses for a better grip on pulling the wires off the plugs and coils. You just use a bungee cord to hold the hoses off to the side so they aren't in the way. Got all the wires off OK except for number 8 which involved some contorting of my hand and just good ol' disregard for keeping skin on my knuckles to get it off. No possible way did I see an angle to get number 8 through the well so I went under the truck but was still having a real hard time positioning a socket on it with the exhaust manifold heat shield on as it really cut down on room to maneuver. The heat shield is only three 10mm bolts so I decided my life would be better if this wasn't in my way. I got it off really easily and that may be the fact I live in the south where rust/corrosion aren't really an issue. Taking that heat shield off made things much better to get a socket on it and get it out. The other three cylinders on the pass side are very easily done through the wheel well with the liner removed...straight shot.

In summary...when deciding to devote a couple hours of your life to this once relatively easy task I highly recommend removing the wheel liner on the pass side, using a bungee cord to pull those heater hoses off to the side after unclipping it from the metal bracket, taking off the manifold heat shield for more room to fiddle around in there, and laying under the truck and going straight up from the bottom to reach cylinder 8 spark plug.

 

[Miami-Dade]

@Darkstar72 Moved you here.

 

[Doubeleive]

I wanted to share the joy I had swapping out the plugs and wires on my 2017 GMC Yukon Denali this past weekend. I watched multiple YouTube videos to prepare myself and give me a plan of action going forward and boy was I glad I watched a few people do this job. I used every single tip/trick that each person shared in their video on getting the dreaded #8 plug buried behind the a/c lines on the pass side. The drivers side is really straightforward with everything in sight and nothing really special there. Just kept swapping out extensions and swivels depending on which plug I was going for. The fun really starts on the passenger side and this is what I did...first jacked the truck up, took off the pass front wheel, and then removed the wheel well liner. According to some videos this is all you need for access...I still was not having an easy time. I went back up top and pulled the plastic retainer out of the metal bracket off the pass side valve cover for the heater hoses for a better grip on pulling the wires off the plugs and coils. You just use a bungee cord to hold the hoses off to the side so they aren't in the way. Got all the wires off OK except for number 8 which involved some contorting of my hand and just good ol' disregard for keeping skin on my knuckles to get it off. No possible way did I see an angle to get number 8 through the well so I went under the truck but was still having a real hard time positioning a socket on it with the exhaust manifold heat shield on as it really cut down on room to maneuver. The heat shield is only three 10mm bolts so I decided my life would be better if this wasn't in my way. I got it off really easily and that may be the fact I live in the south where rust/corrosion aren't really an issue. Taking that heat shield off made things much better to get a socket on it and get it out. The other three cylinders on the pass side are very easily done through the wheel well with the liner removed...straight shot.

In summary...when deciding to devote a couple hours of your life to this once relatively easy task I highly recommend removing the wheel liner on the pass side, using a bungee cord to pull those heater hoses off to the side after unclipping it from the metal bracket, taking off the manifold heat shield for more room to fiddle around in there, and laying under the truck and going straight up from the bottom to reach cylinder 8 spark plug.

i adapt a spark plug socket down 1/4' then use a swivel head ratchet like this one and a breaker bar over that and easy peasy
the swivel head allows just the right angle for clearance

11066 1/4-Inch Drive X 5-5/8-Inch 72-Tooth Swivel Head Ratchet | eBay

Item model number 11066. Included Components - 1/4 Round Flex Head Ratchet (11066). Part Number 11066. Head Type Flat Head Flat Head Flat Head Swivel Head Swivel Head Flat Head and Swivel Head. Head Type Dual Drive Tear Drop Dual Drive Tear Drop Dual Drive Tear Drop Dual Drive Tear Drop Swivel...

www.ebay.com

 

[Doubeleive]

to reach the wire at the plug I use a set of long angled pliers like these, sold at harbor frieght also
there are some out there with a loop on the tip so you don't pinch the wire, but I usually do plugs and wires at the same time so if it tears no biggie

4pcs 11" Long Needle Nose Pliers Set Straight,45 Degree,90 Degree And "S" Curved | eBay

Heavy Lined Teeth. 11" long,Straight,45%,90% And "S" Shape.

www.ebay.com

 

[Joseph Garcia]

I wanted to share the joy I had swapping out the plugs and wires on my 2017 GMC Yukon Denali this past weekend. I watched multiple YouTube videos to prepare myself and give me a plan of action going forward and boy was I glad I watched a few people do this job. I used every single tip/trick that each person shared in their video on getting the dreaded #8 plug buried behind the a/c lines on the pass side. The drivers side is really straightforward with everything in sight and nothing really special there. Just kept swapping out extensions and swivels depending on which plug I was going for. The fun really starts on the passenger side and this is what I did...first jacked the truck up, took off the pass front wheel, and then removed the wheel well liner. According to some videos this is all you need for access...I still was not having an easy time. I went back up top and pulled the plastic retainer out of the metal bracket off the pass side valve cover for the heater hoses for a better grip on pulling the wires off the plugs and coils. You just use a bungee cord to hold the hoses off to the side so they aren't in the way. Got all the wires off OK except for number 8 which involved some contorting of my hand and just good ol' disregard for keeping skin on my knuckles to get it off. No possible way did I see an angle to get number 8 through the well so I went under the truck but was still having a real hard time positioning a socket on it with the exhaust manifold heat shield on as it really cut down on room to maneuver. The heat shield is only three 10mm bolts so I decided my life would be better if this wasn't in my way. I got it off really easily and that may be the fact I live in the south where rust/corrosion aren't really an issue. Taking that heat shield off made things much better to get a socket on it and get it out. The other three cylinders on the pass side are very easily done through the wheel well with the liner removed...straight shot.

In summary...when deciding to devote a couple hours of your life to this once relatively easy task I highly recommend removing the wheel liner on the pass side, using a bungee cord to pull those heater hoses off to the side after unclipping it from the metal bracket, taking off the manifold heat shield for more room to fiddle around in there, and laying under the truck and going straight up from the bottom to reach cylinder 8 spark plug.

Thank you for your write-up on your experience. Much appreciated.

 

[clogan2]

I had so much trouble just getting the wires loose from the plugs that I gave up after three, and paid my local shop to do the other 5. Decided I was too old for all that trouble and contorting.

 

[RB_Trucker]

It’s nice to see other accomplish this task their own way, I usually do wires and plugs at the same time so I have no cares on what happens to the wires, but yes that #8 plus has been and will most always be one of GM’s most hated parts

Just don’t forget the dielectric grease for the plug boot and coil pack boot, most of my plug wires tore apart because they “sealed” themselves to my plugs.

 

[TheBigCheezeBall]

Thank you for posting this. I was going to attempt this today while replacing the struts, but I couldn't figure out how to get my hand past those heater lines to even remove the wire. I ended up punting on it for today as I didn't want to break those plastic heater line connections. I will try to pull of the heat shield and see if I can get it any easier.

 

[TheBigCheezeBall]

I wanted to share the joy I had swapping out the plugs and wires on my 2017 GMC Yukon Denali this past weekend. I watched multiple YouTube videos to prepare myself and give me a plan of action going forward and boy was I glad I watched a few people do this job. I used every single tip/trick that each person shared in their video on getting the dreaded #8 plug buried behind the a/c lines on the pass side. The drivers side is really straightforward with everything in sight and nothing really special there. Just kept swapping out extensions and swivels depending on which plug I was going for. The fun really starts on the passenger side and this is what I did...first jacked the truck up, took off the pass front wheel, and then removed the wheel well liner. According to some videos this is all you need for access...I still was not having an easy time. I went back up top and pulled the plastic retainer out of the metal bracket off the pass side valve cover for the heater hoses for a better grip on pulling the wires off the plugs and coils. You just use a bungee cord to hold the hoses off to the side so they aren't in the way. Got all the wires off OK except for number 8 which involved some contorting of my hand and just good ol' disregard for keeping skin on my knuckles to get it off. No possible way did I see an angle to get number 8 through the well so I went under the truck but was still having a real hard time positioning a socket on it with the exhaust manifold heat shield on as it really cut down on room to maneuver. The heat shield is only three 10mm bolts so I decided my life would be better if this wasn't in my way. I got it off really easily and that may be the fact I live in the south where rust/corrosion aren't really an issue. Taking that heat shield off made things much better to get a socket on it and get it out. The other three cylinders on the pass side are very easily done through the wheel well with the liner removed...straight shot.

In summary...when deciding to devote a couple hours of your life to this once relatively easy task I highly recommend removing the wheel liner on the pass side, using a bungee cord to pull those heater hoses off to the side after unclipping it from the metal bracket, taking off the manifold heat shield for more room to fiddle around in there, and laying under the truck and going straight up from the bottom to reach cylinder 8 spark plug.

Thanks again for posting this. I tackled this a couple weeks ago, and removing the heat shield is the way to go. I just removed the bolts and shifted it down and forward about 6 inches and was able to gain the clearance I needed to access the plug from the top / wheel well. I had luck breaking the plug loose from underneath, but needed to put the socket on / new plug in from the top. Unfortunately, I also managed to break the wire on old #8 getting it off. Seems as though it decided to fuse to the plug .... At least the parts store had the OE wires in stock. Other than that, it went as smooth as I could ask for. Hopefully I don't need to do this again for another 8 years. All in total job took about 4 hours, but that was with my 8 year old son 'helping'. Number 8 plug was probably 2.5 of that (including the parts store run).

 

[89Suburban]

Yup watch those plastic heater tee's boys when fiddling with those hoses. Might just want to tackle those as well while you at it IMHO.