Do 08 or above RL have #4 cylinder issue?

[IanRTL]

Originally Posted by speedlever

Metric or SAE allen?

Don't really know. I just use the one that fits.

[speedlever]

See? Now I gotta go pull out my allens and try them to get the right size. Told you it wuz gonna take me at least 15 minutes to find the right tools. Sheesh.

[Bethard728]

Originally Posted by IanRTL

The reason why it's only happened to older RL's is because it seems to take a good bit of time before this condition rears its ugly head. It could be that it has the potential to affect all RL's, Pilots, Odyssey's and even Accords. On the other hand, I changed my spark plugs in my '07 at 110k miles or so. The stock plugs weren't loose nor did they give me any trouble when taking them out. I consider myself lucky in that sense. Others have not had as much luck. The best thing to do would be to pull the coil packs and check the torque on the plugs once a year. When I initially put my new set in, I did not use an actual torque wrench and tightened them by hand. About 10k miles later after not feeling good about not using the wrench, I checked them all. To my near horror, two of the front were hand tight and the rest were not very tight. I made sure to tighten them all to the recommended 13 lb./ft. and plan to check them all again in the spring.

This might of been covered in a different posts, but I didnt see it right away. How does the spark plug coming loose effect the cylinder? I cant see how it could do any more harm than pulling out the threads. I cant see how a loose plug could do any damage to the valves, piston, or cylinder bore. Unless part of the plug breaks off. Anyway, this has been bothering me. I am the type that needs a logical explanation in my brain before I am a believer.

[speedlever]

My understanding is that the heat of combustion leaking past the loose plug destroys the plug (and parts fall inside the cylinder) and the heat will likely damage the coil pack. Although that last will be minor in the scheme of things.

[IanRTL]

Originally Posted by Bethard728

This might of been covered in a different posts, but I didnt see it right away. How does the spark plug coming loose effect the cylinder? I cant see how it could do any more harm than pulling out the threads. I cant see how a loose plug could do any damage to the valves, piston, or cylinder bore. Unless part of the plug breaks off. Anyway, this has been bothering me. I am the type that needs a logical explanation in my brain before I am a believer.

From what I can gather, it's due to the extra amount of heat and pressure that escape past the threads. The material on the head around the spark plug hole isn't all that thick, and due to the excessive heat/cooling cycles and the abnormal pressure placed on that area, the head forms a crack. This is where the low compression comes from and why the head must be replaced. If it goes too long without being caught, the shortblock may sustain damage, too. IIRC, there was a picture of one of these dreaded cracks from one of the threads regarding this issue. I think it was either eburcher or davidsavournin that provided it. Again, there is no absolution on this issue, but this does seem to be the likely culprit.

[Bethard728]

Originally Posted by IanRTL

From what I can gather, it's due to the extra amount of heat and pressure that escape past the threads. The material on the head around the spark plug hole isn't all that thick, and due to the excessive heat/cooling cycles and the abnormal pressure placed on that area, the head forms a crack. This is where the low compression comes from and why the head must be replaced. If it goes too long without being caught, the shortblock may sustain damage, too. IIRC, there was a picture of one of these dreaded cracks from one of the threads regarding this issue. I think it was either eburcher or davidsavournin that provided it. Again, there is no absolution on this issue, but this does seem to be the likely culprit.

Thanks Ian and Speed. That makes sense.

I pulled a few plugs from the front bank awhile back. Probably around 150K or so. I just did it to check them out to see if the plugs appeared worn. I was very surprised to find the middle plug on the front VERY loose. I had the ratchet on it, but I bet I could of backed it out by hand. I didnt give it a thought...the plugs looked good, so I put them back in (did not torque with wrench) and planned to check them again at 200K. Now Im thinking I should at least put the torque wrench on it. I just always thought "goot-n-tight" was the proper spec for spark plugs.

[speedlever]

Aluminum heads and too tight could = stripped spark plug threads. I do NOT wanna go there.

Just remember no anti-seize on the NGK plugs.

Very interesting that you found cylinder 5 with a relatively loose spark plug.

[Bethard728]

Originally Posted by speedlever

Aluminum heads and too tight could = stripped spark plug threads. I do NOT wanna go there.

Just remember no anti-seize on the NGK plugs.

Very interesting that you found cylinder 5 with a relatively loose spark plug.

I know this was another post, but was there ever a decision made on the use of anti-seize for reinstalling old plugs? I was thinking someone said the original metal composition that took the place of anti-seize would degrade and was not viable for re-install. I cant seem to find that post now though.

I did NOT put anti-seize on when I put them back in.

[speedlever]

No, I don't believe reinstalling old plugs with AS was ever resolved. I don't know if the NGKs are a use once and toss or just what.

[IanRTL]

I wouldn't use the AS on the plugs at all - new or old. And I would totally recommend using the torque wrench. As I said, I always thought "good and tight" was the rule with plugs, too. I tightened mine by hand the first time and when I checked them 10k later, they were ALL loose. I used the torque wrench and 13 lb./ft. is certainly tighter than what I did the first time. Too tight is probably just as bad as too loose, though. Use a wrench!