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paker

Surprise in spark plug change

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Odometer read 94k miles. According to this forum, time to replace spark plugs. Bought spark plugs, PCV valve, and plenum gasket set as recommended here. Watched a few youtube videos. Front 3 were easy. Now rear 3. The coils wouldn't come out. Did twisting and pulling alternatingly. No use. Yanked really hard and they came out. Dropped 5/8" socket into the well to remove the plug. No engagement. What the heck is going on? Pulled out a mirror and looked into the well. There is rubber at the bottom! Apparently, the rubber boot was welded to the spark plug ceramic (due to heat and age I suppose). When the coil was pulled up, the bottom portion got torn up and remained in the well. What a mess! Beer time. I need to calm down. I remembered a dental pick set. Relying on the feel, I slowly detached the rubber from the plug post. After 30 miinutes all rubber pieces came out.

 

Old spark plug gaps were between 70 and 80 mils, really worn down from 54. I thank the forum for recommending plug change at 90K miles. Could have been earlier like 70 or 80k miles. My next plug change will be after 70k miles.

 

Lessons learned:

1) Be prepared for boot damage. Apply silicone dielectric grease to the boot to prevent boot-to-spark plug welding.

2) This video was most helpful except for a bolt in the far back (2:45) and an electrical plug (8:00). Both are missing in 2010. The electrical plug is apparently for heated PCV valve. 2010 has a non-heated version.

 

Edited by paker
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This exact thing happened to me with 2 of the 3 rear plugs, after googling wth was going on I learned this is a very common thing to happen. Shit design, don't blaim yourself.

Edited by erikrichard

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On 11/18/2019 at 1:06 PM, erikrichard said:

This exact thing happened to me with 2 of the 3 rear plugs, after googling wth was going on I learned this is a very common thing to happen. Shit design, don't blaim yourself.

 

Not a shit design, happens with literally every kind of plug boot out there if not properly maintained (dielectric grease and regular maintenance).  This has never happened to any of my cars or the hundreds that I work on solely because we change plugs every 50K and clean everything and lubricate.  Maintenace is key to easy work, even on something that isnt an optimal design.

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My 2007 has the extra connector on the intake.  Big pain  to connect and disconnect blind.  Mine is due again soon.  Done at 90,000 first time and we are at 145,000 now.  I did replace a coil 6 months ago because I couldn't get just the boot and it's been fine since.   Next time I'll replace all the boots while the intake is off.  Luckily the bad coil was in the front.

It takes 20 minutes to change all 6 plugs in my wife's 4.0 Grand Cherokee.   :)  

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