Changing spark plugs.

LouisTB

Original poster
Member
Apr 12, 2016
120
Tampa, FL
I'm getting ready to change out the spark plugs on my 06 trailblazer I6, which has 145k miles on it. Is there anything I need to do in preparation before I start pulling my old plugs out?
 

HARDTRAILZ

Moderator
Nov 18, 2011
49,665
Make sure you get the proper AC Delco Iridium plugs. Nothing else is worth a crap.

i did a set on an Envoy this weekend and only used a flat screwdriver, 10 and spark plug sockets. You will need 6 inches of extension for the plug socket to reach down into well for plug.
 

LouisTB

Original poster
Member
Apr 12, 2016
120
Tampa, FL
Make sure you get the proper AC Delco Iridium plugs. Nothing else is worth a crap.

i did a set on an Envoy this weekend and only used a flat screwdriver, 10 and spark plug sockets. You will need 6 inches of extension for the plug socket to reach down into well for plug.
Yea I already bought the correct plugs. I was more wondering if I needed to unhook the battery like some people say.
 

RTTBLT1

Member
Jan 25, 2016
512
Louisburg, KS
I agree with @HARDTRAILZ, you want AC Delco Iridium Plugs. And if you can, may as well replace all the Coil Boots while your there. Also when I did mine i took a Shop Vac to the SP Wells to remove anything that may have been in the Wells prior to removing the SP's.

Edit: I did mine with the Battery Cables in place...and i still have all my body parts, lol.
 
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HARDTRAILZ

Moderator
Nov 18, 2011
49,665
I unhooked the battery and cleaned the throttle body of the one I did while in there. Took extra 15 minutes and now it idles better for him. Just 4 bolts for TB and 1 for battery.
 

LouisTB

Original poster
Member
Apr 12, 2016
120
Tampa, FL
I agree with @HARDTRAILZ, you want AC Delco Iridium Plugs. And if you can, may as well replace all the Coil Boots while your there. Also when I did mine i took a Shop Vac to the SP Wells to remove anything that may have been in the Wells prior to removing the SP's.

Edit: I did mine with the Battery Cables in place...and i still have all my body parts, lol.
Hmmmm....I didn't think about the coil boots at all but I'll keep that in mind
 
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mrrsm

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@MAY03LT produced a nice "How-To" Video (click on the Youtube Icon):

(Thanks to seeing this years ago...I was able to get mine changed fast enough to loan the TB to my son when he needed transportation on very short notice to make it to a job interview ON TIME. As a result...he got the job!...I can't thank @MAY03LT enough...EVER!)
 
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HARDTRAILZ

Moderator
Nov 18, 2011
49,665
I was asked to swap the boots on the one I did, so I did and personally thought it a waste of time. I did not bother on my personal truck. The boots I took off the Voy yesterday look brand new at 125K.
 
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LouisTB

Original poster
Member
Apr 12, 2016
120
Tampa, FL
I unhooked the battery and cleaned the throttle body of the one I did while in there. Took extra 15 minutes and now it idles better for him. Just 4 bolts for TB and 1 for battery.
The TB was recently cleaned maybe 2-3 weeks ago so I think I'm okay there.

I was asked to swap the boots on the one I did, so I did and personally thought it a waste of time. I did not bother on my personal truck. The boots I took off the Voy yesterday look brand new at 125K.
I guess it'll just end up being if they look nasty, I'll put them back in until I can get some new ones.
 
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jsheahawk

Member
Jan 16, 2013
533
Kansas City
Don't do it on a hot engine, torque them to spec (which I think is printed on the top of the head), and check for oil in the wells when you're changing them. It's common in our trucks.

Also, go ahead and buy yourself something nice because you just saved yourself a good chunk of change. :2thumbsup:
 

Mounce

Member
Mar 29, 2014
13,667
Tuscaloosa, AL
I replaced the boots on mine just for good measure. Nothing appeared to be wrong with the stock boots but I had the new boots on hand so I threw them on.

Hardest part is getting coil #1 out and back in due to the wiring harness running over it.

Put antisieze on the plug threads and a dab of dielectric grease in the boot where the plug goes in and you're good to go. Pretty easy job.
 
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Texan

Member
Jan 14, 2014
622
My spark plug socket has a rubber insert that fits
over the porcelain. Helps to keep the socket vertical
and not crack the porcelain. FWIW
 
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Mounce

Member
Mar 29, 2014
13,667
Tuscaloosa, AL
I used a magnetic one I picked up at orielly's. It was magical. Perfect tool for the job, new rubber ones hold way too tight and I was scared it would pull off of the extension down inside the head. The magnetic one held great and let go when you wanted it to.
 

LouisTB

Original poster
Member
Apr 12, 2016
120
Tampa, FL
Don't do it on a hot engine, torque them to spec (which I think is printed on the top of the head), and check for oil in the wells when you're changing them. It's common in our trucks.

Also, go ahead and buy yourself something nice because you just saved yourself a good chunk of change. :2thumbsup:
Okay will do now I just need a day off to actually get around to doing them. Having to work 13 days straight cause one of our guys at the shop is out leaves very little down time :/. I'll make sure to buy myself something nice, which usually equates to buying something for the trailblazer haha
 

dkvasnicka

Member
Jul 24, 2015
366
Czech republic, Europe
So Denso Iridium ITV16s are a no no? It's a lot harder to get ACDelco plugs here in Europe and Denso is a quality brand AFAIK, no shit... anyone has experience with these in our trucks?
 

HARDTRAILZ

Moderator
Nov 18, 2011
49,665
Never heard of them, but virtually every plug other than the Delco Iridium has caused issues with the 4.2 when someone tries it
 

dkvasnicka

Member
Jul 24, 2015
366
Czech republic, Europe
LOL, I just found that I can get 6 original 41-103s from US eBay for less (including shipping overseas!) than if I bought 6 Densos here, locally :smile: Problem solved.

I'm just a bit worried about the shipping process... damaging a spark plug is pretty easy :/
 
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HARDTRAILZ

Moderator
Nov 18, 2011
49,665
I would not be worried at all about shipping a spark plug that will have a cylinder(plastic or cardboard) around the tip and is in a box and quite possibly inside another box.
 

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
It is quite possible that your Denso plugs are the same as the Delcos, which are supposedly made by NGK. If it's running fine, don't worry about it. They won't explode or anything.
 

dkvasnicka

Member
Jul 24, 2015
366
Czech republic, Europe
It is quite possible that your Denso plugs are the same as the Delcos, which are supposedly made by NGK. If it's running fine, don't worry about it. They won't explode or anything.

I'm going to do them once outside temps jump a bit more up... and I was set on ordering Densos the whole time. So it's good I now actually tried to search for more possibilities instead of just presuming :wink:
 
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Chickenhawk

Member
Dec 6, 2011
779
Here are my inputs.

#1 - If you are having trouble getting to the #1 plug and coil because of the wiring loom running in front of it, just pry off the loom. Snap the plastic connector holding it to the hole. The secret here is that the plastic connector is exactly the same connector holding door panels in place, and if you break it off, you can buy new ones at any auto parts store for a few pennies.

#2 - Don't sweat plug gap. People who tell you that you MUST gap the plugs before installing are old-school. Dinosaurs are dead; we don't need to walk to school in snow twelve months of the year uphill both ways; and fire has been invented. More plugs have been damaged by people thinking they have to gap them than are improved by these little tweaks. Spark plugs have a very wide range of acceptable gaps; trying to gap iridium plugs can damage them very easily. If it's close and has not been damaged in shipping, just put them in. Gapping them more carefully than that accomplishes NOTHING. (I have seen HUGE gaps in worn-out plugs and they still run fine.)

#3 - Many owners seem to roast a coil right after a plug change. The reason is simple. They are not easy to get seated perfectly, and if seated incorrectly, can roast themselves quickly. Take the time to get them perfect and you will never need to buy a new coil. They SEEM like they are seated, but aren't. Take your time.

#4 - Forum members have tried every applicable plug known to mankind, and nothing works. Just trust us; don't piss around, don't experiment and don't believe market claims. Just get the 41-103 AC Delcos and be done with it.
 

Gary P

Member
Apr 18, 2016
13
Upstate NY
Here are my inputs.

#1 - If you are having trouble getting to the #1 plug and coil because of the wiring loom running in front of it, just pry off the loom. Snap the plastic connector holding it to the hole. The secret here is that the plastic connector is exactly the same connector holding door panels in place, and if you break it off, you can buy new ones at any auto parts store for a few pennies.

#2 - Don't sweat plug gap. People who tell you that you MUST gap the plugs before installing are old-school. Dinosaurs are dead; we don't need to walk to school in snow twelve months of the year uphill both ways; and fire has been invented. More plugs have been damaged by people thinking they have to gap them than are improved by these little tweaks. Spark plugs have a very wide range of acceptable gaps; trying to gap iridium plugs can damage them very easily. If it's close and has not been damaged in shipping, just put them in. Gapping them more carefully than that accomplishes NOTHING. (I have seen HUGE gaps in worn-out plugs and they still run fine.)

#3 - Many owners seem to roast a coil right after a plug change. The reason is simple. They are not easy to get seated perfectly, and if seated incorrectly, can roast themselves quickly. Take the time to get them perfect and you will never need to buy a new coil. They SEEM like they are seated, but aren't. Take your time.

#4 - Forum members have tried every applicable plug known to mankind, and nothing works. Just trust us; don't piss around, don't experiment and don't believe market claims. Just get the 41-103 AC Delcos and be done with it.
Good tips. Thanks! :2thumbsup:
What's your opinion on using never seize on the spark plug threads? Some folks have told me they always use it, and others tell me it's not needed, and could cause issues.... :confused:
 

mrrsm

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Oct 22, 2015
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Tampa Bay Area
The Anti-Sieze is definitely the way to go... it's application just requires leaving the first two or three thread lines adjacent the electrode ends of the plugs completely clear of the stuff, as the nose-in threads have a very slight taper and this prevents the material from oozing down into the combustion chamber. Permatex Part# B000AAJTXY seems to be the "Best Flavour" of the stuff because it uses pulverized Aluminum rather than Copper in the emollient and this will prevent Tri-Metal Electrolytic Welding of the Spark Plug threads to the deep, center-bored holes in the Aluminum Cylinder Head.

This is one of those "A Very Little Amount...Goes a Very Long Way..." kind of material... so less is best....and only "finger-thread" the plugs in using a Combo-style 3/8" Drive, Shorty, 5/8" Extension Spark-Plug Wobble Socket (No 3/8" Ratchet Handle attached just yet...) and turn them in very carefully to avoid cross-threading. If you start with Cylinder #6 and work your way towards Cylinder #1.... you'll be fresh and alert... and won't get frustrated and too hasty with how these go in. The Last Place in the World to cross-thread anything on this engine.. is near the back of the block.Screenshot from 2016-04-21 08:43:30.jpg Screenshot from 2016-04-21 08:44:04.jpg
 
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Gary P

Member
Apr 18, 2016
13
Upstate NY
Thanks for the quick reply!

I've been accustomed to being careful with aluminum heads for many years, as all of my motorcycles had them. Totally understand the "little goes a long way" comment. Will be picking up some of that Permatex lube you pictured. Thanks again! :2thumbsup:
 

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
I'm going to do them once outside temps jump a bit more up... and I was set on ordering Densos the whole time. So it's good I now actually tried to search for more possibilities instead of just presuming :wink:

I assumed that you had already changed them to the Densos and contemplating switching to the Delcos. Yes, better (and cheaper) to get the Delcos :2thumbsup:
 

Daniel644

Member
Feb 27, 2015
573
didn't feel like reading all the comments so if this was mentioned already then so be it.

Start with a cold engine (preferably after sitting over night), extension and swivel for getting to the last plug. I unhooked my battery but that was because I also did the throttle body cleaning at the same time, normally on every other car I've owned i've never disconnected a battery for a plug change. beyond that it depends on the size of your hands, I was able to slide my hands down into the tube far enough to handle the spark plugs.

edit: for what it's worth this is the third easiest plug change I've done, with only my 4 cylinder mid 90's hondas being easier, but it impossible for anything to be easier then those.
 

LouisTB

Original poster
Member
Apr 12, 2016
120
Tampa, FL
I replaced the boots on mine just for good measure. Nothing appeared to be wrong with the stock boots but I had the new boots on hand so I threw them on.

Hardest part is getting coil #1 out and back in due to the wiring harness running over it.

Put antisieze on the plug threads and a dab of dielectric grease in the boot where the plug goes in and you're good to go. Pretty easy job.
I replaced the boots on mine just for good measure. Nothing appeared to be wrong with the stock boots but I had the new boots on hand so I threw them on.

Hardest part is getting coil #1 out and back in due to the wiring harness running over it.

Put antisieze on the plug threads and a dab of dielectric grease in the boot where the plug goes in and you're good to go. Pretty easy job.
As for the dielectric grease, should I use like a q-tip to get it in the boot or just try to pack alittle in with my finger?
 

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
I usually put a dab in the boot and spread it around inside with a small screwdriver.
 

mrrsm

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Oct 22, 2015
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Tampa Bay Area
I used a magnetic one I picked up at O'rielly's. It was magical. Perfect tool for the job, new rubber ones hold way too tight and I was scared it would pull off of the extension down inside the head. The magnetic one held great and let go when you wanted it to.

@Mounce 's Idea about this Design prompted me to look into getting one myself and THIS Tool seems to have all "The Magical" aspects he mentioned above:

s-l500.jpg



GearWrench 80546 5/8-Inch x 6-Inch Swivel Spark Plug Socket (Magnetic)
s-l1600.jpg
 
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Mooseman

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Dec 4, 2011
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wormwood1978

Member
Jan 3, 2015
75
Sorry but not really sorry for bumping this thread. I took many of pointers in this thread and had no problems doing the spark plug change on my 08 TB, 85,000 miles, rust belt. The Gearwrench swivel spark plug socket was awesome and I don't think I could have done the job without it. Finally, I got the Ac Delco plugs from RockAuto delivered for $36. This does not include the $3 off per plug mail in rebate that expires 8/31/19.
 

Mektek

Member
May 2, 2017
656
FL
LOL, I just found that I can get 6 original 41-103s from US eBay for less (including shipping overseas!) than if I bought 6 Densos here, locally :smile: Problem solved.

I'm just a bit worried about the shipping process... damaging a spark plug is pretty easy :/

Be careful with ebay plugs. There are fake ACDELCO plugs sold there by chinese con artists. If the price is suprisingly cheap from hong kong or china then it's probably a fake. How good is the fake?> Who knows??????

I bought this set. Seems like it should help me nicely to get to the one plug under the firewall.

sada-3-8-klicu-na-svicky-6ks-yt-0534-yato-original.jpg

I used an air ratchet. Seemed like the only way.
 

crimecanine

Member
Jan 16, 2019
10
USA
#3 - Many owners seem to roast a coil right after a plug change. The reason is simple. They are not easy to get seated perfectly, and if seated incorrectly, can roast themselves quickly. Take the time to get them perfect and you will never need to buy a new coil. They SEEM like they are seated, but aren't. Take your time.
In what way are the coils tricky to seat properly, or, how can you tell the coils are seated properly? If seating new boots onto the coils is tricky, then I understand. But, if seating the coils is tricky, then I'm not sure I get it.

(I replaced my plugs and boots yesterday and haven't cranked the engine yet, so the process is fresh on my mind, and I still have time to revisit it. I thought that in the process, I would understand what #3 means. Seating each coil+boot back onto the plug and tightening the coil bolt to spec didn't seem tricky, though, so I don't know whether I missed some detail. You just ensure that the bottom end of the boot goes onto the top of the spark plug, push down, and tighten the coil bolt, right?)
 

mrrsm

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Oct 22, 2015
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On the Question of...

"How Do I Tell the FAKE ACDelco Spark Plugs from the REAL Ones?"

This comes 'Straight from The Horse's Mouth'...


 
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Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
And we have our own thread about them:

In what way are the coils tricky to seat properly, or, how can you tell the coils are seated properly?
What usually happens is that the boot is not centered onto the plug and basically gets squished between the plug and the plug well in the head. You have to be sure that you are driving the boot and coil straight down and feel it engage the plug.
 

Brian K

Member
Apr 5, 2012
32
I just replaced my plugs @ 160K miles with Autolite XP5263 Iridium I got from RockAuto. It was becoming hard to start so thought a plug change was worthwhile. No issues and the old ones were nice and light brown so my cylinders should be in good shape and there was no oil in the plug wells. Put some Never Seize on the threads and some silicone grease on the boots and cleaned the TB while at it. Torqued to 13 Ftlbs. Runs great again and starts right up. I hope these Autolites last. I see most use AC Delco which I had in there for the past 75K miles but these so far are smooth and I'm happy.
 
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