Had my first "sketchy" 100k spark plug replacement

[The Critic]

Up until now, I had been in disbelief that 100k spark plug changes could result in spark plugs being stuck inside, as all of the plugs I've pulled (to date) came out without too much drama.

I did a 2005 G35 tonight, and it had 91k on the original plugs.

The cylinder #3 and #6 plugs were very difficult to remove. I used my 14" Snap-On Ratchet (lots of leverage) and I was putting a lot of force on the ratchet during the removal process. As you can see in the pictures, 4 out of the 6 plugs had tons of grit and carbon in the threads, while two of the 6 did not. The ones that were difficult to remove also had some rust on the threads, which is quite odd.

Not sure what could've caused this problem. I put back another set of NGK Double Platinums and torqued them to 18.5 ft-lbs.

 

[nightwalker]

I use to work as a technician for Infiniti. We typically recommended spark plugs at 60,000 because we were getting miss-fire complaints long before the 90,000 mile interval.

Did you have any oil contamination on the back spark plugs? Be forewarned, the valve cover and spark plug tube seals cannot be bought separately.

 

[The Critic]

Originally Posted By: nightwalker
I use to work as a technician for Infiniti. We typically recommended spark plugs at 60,000 because we were getting miss-fire complaints long before the 90,000 mile interval.

Did you have any oil contamination on the back spark plugs? Be forewarned, the valve cover and spark plug tube seals cannot be bought separately.

Cyl #6 did have a lot of oil in the hole, so a new valve cover will be installed on that bank soon.

Yeah, I am aware of the one-piece ordeal. It really stinks that you have to buy a new valve cover (which costs $200) in order to fix this problem.

The plugs did not appear to be completely toast on this car but I have heard/seen very worn plugs at this mileage on G35s that were driven hard.

 

[SteveSRT8]

Those plugs look great and could go much longer in my car. But plug life is very driver dependent and platform specific.

I doubt the removal issues were anything but moisture issues or salt, etc., as I have easily pulled out 200k mile plus plugs down here in Sunny Fl.

 

[JHZR2]

6 cyl + FWD = what a pain.

I'd be scared to exert too much leverage.

But I guress what can you do? Did you chase the threads?

 

[Eddie]

6 cyl, when engine is sideways= a pain.

 

[Sayjac]

Quote:
6 cyl + FWD = what a pain.

I'd be scared to exert too much leverage.....

The G35 is a rear drive vehicle.

As noted above, the business portion of the plugs look quite good imo at 91k. I like NGK plugs, whether they be Iridium or Platinum.

 

[Falken]

Honda Fit is a pain to change the plugs too.

I have no problem doing it, but I have to take off the upper and lower cowl to do it.

The upper cowl you break a lot of 5$ blue clips as they are heat stressed from the sun.

If you don't buy new ones the windshield wiper cowl doesn't sit flat against the glass.

The plugs are at the back of the firewall. If you have small hands and are patient you can pull the coils off after unbolting them and blow air down the holes to get any grit out and extract the plugs.

I may actually pay the dealer to do it for me in case I strip the threads getting the plug out.

But I would watch them do it like a hawk, because they may "say" they changed the plugs if they quickly check that you have no CEL. If you do they'd scan it and see if they are misfires. If they're not, then they hand you 4 old plugs and say the job is done and charge you anyway for a service they didn't do.

I have seen a lot of these plugs pulled, and aside from them seizing into the aluminum head they are actually good for the mileage they say.

I would just change them out early to prevent them from getting stuck in the head. Also, if some plugs are loose and getting blow by, it is best as a PM.

I would also run a Techron type cleaner in my engine a tank of gas prior to pulling the plugs to help loosen any carbon build up on the threads that are in the combustion chamber that would snag the plug in the hole.

 

[doitmyself]

I don't know if there is any logical basis for this, but when I encounter difficult to remove plugs, I ease them out by alternating loosening/tightening 1/8 turn or so. It scares me to just muscle them out.

With such dirty threads, one has to wonder what the final torque really was.

 

[LargeCarManX2]

I am an ole timer, and ran the plugs on my old 94 3.8 Chrysler V/6 van 245,000 miles before the tranny went south for the 3rd time and I put her to rest. The engine ran wonderful and the plugs were original.

In the old day's...the plug that caused the miss, was the one to be replaced. Anti-seize was used on the threads. But then again, plugs only lasted (in the old day's) 30 to 50 K before going south.

It is amazing how the new spark plug can last so long...congrates on the replacement....guess your good to go for another 100K?

 

[doitmyself]

What I'm wondering........when is The Critic going to hang up a "shingle"?

I'm not looking forward to replacing some shocks and struts on my Caravan.

Do you do house calls, Mr. Critic? It seems that you are a good friend to many.

Everyone, enjoys the holidays!

 

[RF Overlord]

Originally Posted By: doitmyself
when I encounter difficult to remove plugs, I ease them out by alternating loosening/tightening 1/8 turn or so. It scares me to just muscle them out.
That's what I do.

When removing, if the plug starts to bind, I screw it back down a few turns, then try removing it again. This seems to "chase" the threads and make the removal process less "scary". I also always use just a tiny dab of anti-seize.

 

[Doog]

I run iridium plugs 150k. Never a problem. I also always use anti seize. For the next guy who changes them.

 

[OVERKILL]

Originally Posted By: The Critic
Originally Posted By: nightwalker
I use to work as a technician for Infiniti. We typically recommended spark plugs at 60,000 because we were getting miss-fire complaints long before the 90,000 mile interval.

Did you have any oil contamination on the back spark plugs? Be forewarned, the valve cover and spark plug tube seals cannot be bought separately.

Cyl #6 did have a lot of oil in the hole, so a new valve cover will be installed on that bank soon.

Yeah, I am aware of the one-piece ordeal. It really stinks that you have to buy a new valve cover (which costs $200) in order to fix this problem.

The plugs did not appear to be completely toast on this car but I have heard/seen very worn plugs at this mileage on G35s that were driven hard.


That's insane! $200 bucks???? Everybody complains about BMW parts prices, but the VCG's for the i6 are only $45.00 and are a similar arrangement with the plug well seals as part of the package.

 

[Colt45ws]

I do the work it back and forth thing as well.
When I did the plugs on my car, I had one that was rough, and it was packed with carbon in the threads too. I think it may have been loose for whatever reason, permitting combustion gasses to slowly push through the threads. I say this be cause the tip of the COP boot was blackened as well.

 

[cchase]

Originally Posted By: OVERKILL
That's insane! $200 bucks???? Everybody complains about BMW parts prices, but the VCG's for the i6 are only $45.00 and are a similar arrangement with the plug well seals as part of the package.


That's $200 for the valve cover, not the valve cover gaskets.

 

[The Critic]

I tried to screw the plug back in, but it would not turn. In hindsight, I should have stopped and sprayed some PB Blaster in and allowed the penetrating oil to do its job. However, my concern with this practice as always been the possibility of a difficult start afterwards and/or the possibility of fouling the new plug.

It would seem odd that the factory did not properly tighten these plugs, but given the recent Honda V6 plug issues, I would not be surprised.

And I do agree with sayjac that these plugs could have easily stayed inside for another 30k with no performance or driveability issues, but the removal may be even more difficult in the future.

Lastly, the issue of undertightened plugs due to the dirty threads was something I considered. When I started doing the plugs, I did not realize that my neighbor (the owner of the car) had ordered the V-Power plugs instead of the proper double platinum plugs. After 2 plugs, I realized the issue, and had to remove the two I had already installed. Upon removing the 2 V-Power plugs, the amount of force needed for removal seemed about right for 18 ft-lbs, so I think all is OK.

 

[The Critic]

Originally Posted By: doitmyself
What I'm wondering........when is The Critic going to hang up a "shingle"?

I'm not looking forward to replacing some shocks and struts on my Caravan.

Do you do house calls, Mr. Critic? It seems that you are a good friend to many.

Everyone, enjoys the holidays!


Nah, no plans to start my own side business. I only enjoy doing this occasionally. Thanks for the kind words.

Originally Posted By: sayjac
Quote:
6 cyl + FWD = what a pain.

I'd be scared to exert too much leverage.....

The G35 is a rear drive vehicle.

As noted above, the business portion of the plugs look quite good imo at 91k. I like NGK plugs, whether they be Iridium or Platinum.


The G35 is RWD, but replacing the spark plugs is far more difficult than you would expect. Book time on it is 1.7 hours.

http://eturkov.blogspot.com/2010/10/diy-video-g35-spark-plug-replacement.html

 

[KrisZ]

So why no antiseize? will it take a stripped thread to convince you that service manual is not the bible?

 

[OVERKILL]

Originally Posted By: cchase
Originally Posted By: OVERKILL
That's insane! $200 bucks???? Everybody complains about BMW parts prices, but the VCG's for the i6 are only $45.00 and are a similar arrangement with the plug well seals as part of the package.


That's $200 for the valve cover, not the valve cover gaskets.


So you have to buy the entire cover to get the seals? That's even more ludicrous! LMAO!!!