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Discussion Starter · #1 ·
I replaced the plugs on our Terrain last night and in the process of removing the intake manifold, I broke several of the wiring harness retainers on the driver's side of the manifold. Anyone know of the part number or what they are actually called so I can find some replacements? I looked at my local parts store and couldn't find anything that looked like it could take a zip-tie.

Plug Replacement
- took me about 3 hours of taking my sweet time
- New AC/DELCO 41109
- New Intake Manifold Gasket 12691199
- spent more time trying to figure out how to release the EVAP line, the PCV line, and the brake vacuum line than anything else
- 5 plugs looked normal, in decent condition
- 1 plug was a little darker/dirtier than the rest (center rear-bank)
- 76k miles on the factory plugs
- we have had a miss from time to time over the past year...just enough to pop a check engine light once or twice, but it never stuck around
- This video is what I used as guidance
 

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yeah- did mine about 1 month ago.
the wiring harness retainers were difficult to remove.
the connection to the purge solenoid was also hard. Instead I just undid the bolt that holds the solenoid and then lifted them and then removed.
 

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The retainers that I think you are looking for are called wire loom routing clips.
Try the website linked below.


 

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Discussion Starter · #4 ·
Another note, the intake valves looked absolutely horrible. Well…at least I think they do. It isn’t like I have done an inspection on many valves over the years.

Has anyone else looked at their intake valves? How do you clean them? I have read this is one of the biggest drawbacks of DI engines.


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yes- mine had carbon buildup on them.
THey had less than my 2010 Traverse.

The Nox has been all Pennzoil Platinum. The Traverse all Conventional until 150,000.
But- I have yet to get any CEL misfire codes on the Traverse. Im now at 164,000.

I do occiasionally feel little misfires on the Traverse. Usually in winter. Ill scan and its something like 10 misfires.
But I also run a bottle of Techron before an oil change.

Same with the Nox. Bottle before oil change.

To clean the valves - you can have a shop do a walnut blasting to clean them up.
Or you can use wire mesh cleaners and spray cleaners. it is a tedious job as you have to scrap off all the crud- and also turn engine so the valve closes so that stuff does not fall in
 

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Discussion Starter · #6 ·
We usually add Techron a couple of times per year....but that has nothing to do with the valves since the fuel never makes it there in a DI engine. We generally also only run Top Tier fuel in it as well...Hy-Vee, QT, or Costco covers our fueling duties 99% of the time.

As for oil...what ever the synthetic the dealership puts in there. Its only ever had its oil changed at our local GMC dealer since we bought it new 7'ish years ago.

I am thinking about trying out some Seafoam Spray into the intake....but....I won't really be able to see if there is any improvement without taking things all apart....which I have zero desire to do anytime soon.
 

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yes, Techron will not get to the back of the valves.
When I do begin to feel misfires- like I mentioned- its winter, im nearing 3500-4500 miles on the oil change interval. And its on cold morning start and half a mile away from having left home.
Ill feel the misfire. I check and the above 'parameters' are true.
I run a bottle of Techron and this corrects the issue. Leading me to believe its carbon buildup within the cylinder and or the lip of the valve (sticky valves).
But the issue is corrected and it does not get to the point to set a check engine light.
 

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144K miles in my ‘15 V6 Nox and still on original plugs. I bought replacement plugs & intake gaskets 2 years ago when I was around 95K miles...they ride in my trunk just in case I need them in an emergency, but I must admit that I’m still in no rush. Every GM plug I’ve pulled that was rated to go 100K miles has looked like it could go another 100K miles when I pulled it out...I may change them out sometime later this summer...maybe closer to 150K miles...
 
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2011 Equinox 1LT V6 3.0L FWD 174.6k miles
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144K miles in my ‘15 V6 Nox and still on original plugs. I bought replacement plugs & intake gaskets 2 years ago when I was around 95K miles...they ride in my trunk just in case I need them in an emergency, but I must admit that I’m still in no rush. Every GM plug I’ve pulled that was rated to go 100K miles has looked like it could go another 100K miles when I pulled it out...I may change them out sometime later this summer...maybe closer to 150K miles...
I'm about to turn 160k miles on my 2011 with the original factory plugs still in there! I stopped doing "preventative maintenance" about 30 years ago. I wait for symptoms first - and even then I don't do anything. Usually start collecting data at that point! LOL!
 
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Discussion Starter · #10 ·
I normally wouldn't have done plugs this early either...just know that our MPG has been lower than normal as well as the handful of odd stumbles this past year. Figured it wouldn't hurt, but also didn't expect miracles.

This is what 5 of the plugs looked like....the sixth was a tad darker.
17754


Also to note....the OE front brake pads had plenty of life left in them at 76k miles. I would have left them, but was tired of the pulsations coming from the rotors. Even tried re-bedding the brakes a couple of times, but it never quite resolved the issue. So new rotors and new pads and it feels like a brand new car. I "should" have bled the brakes but ran myself out of time.
17756
17755


Only leak I could find appears to be the power steering pump I am guessing? The rest of the engine and bay were completely dry.
17757
 

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I'm about to turn 160k miles on my 2011 with the original factory plugs still in there! I stopped doing "preventative maintenance" about 30 years ago. I wait for symptoms first - and even then I don't do anything. Usually start collecting data at that point! LOL!
…I’m at 159,800 and it’s time for plugs I believe. For about the past 1K miles (over the past week) I can feel a shudder at times which really feels like a misfire. No light yet, but I’m going after the plugs tomorrow. The only other thing, and this concerns me, is that I also just changed the tranny fluid and I hope the slight shudder I feel isn’t the tranny…
 

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Discussion Starter · #13 ·
…I’m at 159,800 and it’s time for plugs I believe. For about the past 1K miles (over the past week) I can feel a shudder at times which really feels like a misfire. No light yet, but I’m going after the plugs tomorrow. The only other thing, and this concerns me, is that I also just changed the tranny fluid and I hope the slight shudder I feel isn’t the tranny…
I hope not tranny either. These aren't known for wave plate failures like the earlier transmissions. We had an '08 with a wave plate failure, and it felt like running over a rumble strip, not a shudder. Our trans in our '15 doesn't shudder, but has a flare that comes and goes in the 2-3 and 3-4 depending if we are turning. It has been here for 50k miles and hasn't gotten any worse or better over the years.....but no shudders.
 

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I hope not tranny either. These aren't known for wave plate failures like the earlier transmissions. We had an '08 with a wave plate failure, and it felt like running over a rumble strip, not a shudder. Our trans in our '15 doesn't shudder, but has a flare that comes and goes in the 2-3 and 3-4 depending if we are turning. It has been here for 50k miles and hasn't gotten any worse or better over the years.....but no shudders.
…the only thing that really makes me worry about the tranny is that at that kind of mileage, I went ahead and put full synthetic fluid in it…it had only had a synthetic blend at the last change at 80K miles. I know that’s a no-no to switch to synthetic engine oil at that high of mileage (I’ve always run synthetic oil in my Nox anyway), but I didn’t think it could cause any tranny issues by switching to full synthetic…at least I hope it doesn’t…
 

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Mine feels like it’s harder to push lately ... like I have to put the pedal down further because it just doesn’t “go” like it used to. Could be plugs, could be transmission, could even be blocked exhaust, I suppose.

I guess I’m gonna have to get off my duff and finally do something!

I did change the oil/filter yesterday ... LOL!
 

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Mine feels like it’s harder to push lately ... like I have to put the pedal down further because it just doesn’t “go” like it used to. Could be plugs, could be transmission, could even be blocked exhaust, I suppose.

I guess I’m gonna have to get off my duff and finally do something!

I did change the oil/filter yesterday ... LOL!
You still on original plugs at 174K?
 

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I would also add - get a can of MAF cleaner.
Give it a good spray to clean that sensor.

 

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Oh man am I stuck! Cylinder 5 plug won’t come out. I’ve got some PB Blaster down the hole and I’ve been getting it to turn back and forth slightly for the past hour, but it’s barely moving! All of the other plugs are changed, but I’m stuck at the moment on this last one. I’m guessing carbon buildup, but I’m scared I’m stripping the head…
 

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@BandDirector : Oh Nooo!! Coming attractions for me, I guess.

Well, I think I would just continue loading it up with the PBBlaster and gently trying to remove it for a minute or so, then walk away for a half hour or so, and repeat this cycle hoping the PBBlaster works it’s way in to the point where one of the 1 minute removal attempts is successful.

Did you put any PBBlaster on any of the other 5, or only on this last one when you had to?

Did you heat the engine up first and remove the plugs while the engine was still hot, or did you do it all cold, or heat it up, let it cool, then remove them? Honestly don’t know if there’s a “right” way, “better“ way, or “recommended” way with plugs that have been in the engine as long as ours have been...
 
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