Anyone ever hear of spark plugs backing out?

[stargazerngc]

Hey everyone. I found this thread about ten minutes ago after a google search, and it was too informative not to comment. I don't have a Pilot, but I do have a 2006 Accord (I hope this won't be considered off topic because of that). Anyway, I had this exact problem earlier today right after merging onto the interstate. As I was accelerating I heard a ticking noise. I started to take my foot off the accelerator when I heard a loud "ka-chunk" noise and my car started to shake. Thought I had a flat until I had pulled over to the side of the road and saw the engine light was flashing. I popped the hood and there was some smoke along with a burned smell. The plastic in the front of the engine above the cylinder heads where the oil cap is was cracked almost in half. Got a tow truck and managed to find a Honda dealer a couple miles away (I was about 4 hours from home getting ready to drive back). Guy at the Honda dealership said that the plugs had backed out which caused them to essentially explode in the engine. The resulting damage caused the gaskets to fail dumping oil in my engine. The whole thing is ruined and I can either get a used one (aka junkyard) for around four grand or a new one for about six grand. I had never heard of this problem until today, and am shocked at the number of posts on the topic. Like most other people here I'm rather good about having maintenance done on my car. I got it used with 31K miles on it, so I don't know if the plugs were ever touched before then. As far as I know they have never been monkeyed with since I got it since I have only had it to Honda dealerships for checkups. The only time I go anywhere else is for oil changes.

What's the reality that contacting Honda will actually result in them helping me? I've had the car since 2007 and it's got ~ 94K miles on it now.

Sucks to be me apparently. Also, Happy New Year everyone. And thanks for the info.

[KKL]

Originally Posted by KKL

After reading the horror stories on plugs backing out, I replaced the original plugs with new ones at 72K about a month ago. The old plugs were tight. I installed the new plugs per NGK's instructions: contact then a further 1/2 to 3/4 turn. I also used anti-seize on the threads. The horror stories kept coming on this thread and I got worried. Last weekend I checked the recently installed plugs and they were kind of LOOSE. So I retightened them again and gave the wrench handle an extra tug at the end just to make sure. Will check again in a couple of months. I am pretty well practiced now and can do the check in less than 0.5 hour.

I just did a second follow-up check. Two plugs out of six was not as tight as when I re-tightened them 2.5 months ago. I re-tightened again and will check again in a few months. This spark plug thing certainly does not inspire confidence. Maybe instead of worrying about the plugs "welding" to head (I used anti-seize), one should put a thread sealer on the plugs!?

[samc]

I can't believe these plugs are "backing out" so frequently. I've done plenty of plug changes on other cars and never had a problem. I guess a torque wrench is indeed necessary.

I wouldn't worry about thread sealers, Just use a bit of anti-seize and torque properly.

[KKL]

I would not have believed that the plugs could loosen up until I experienced it myself. I have done enough spark plugs over the years to tell what 5, 10, 15, 20 ft-lb feel like without the benefit of a torque wrench. This loose plug thing is definitely a first for me. The comment about thread sealer was stated in wonder. Maybe one should just leave the threads dry as they do at the factory, no oil or anti-seize. I am beginning to wonder about the individual coil setup of today's engines, whether there is some hidden issue in the mechanical packaging that induces unwanted vibrations that could potentially loosen the plugs. Maybe some cognoscenti on this forum could shed light on this suggestion.

[hoorah]

Well, consider me sufficiently worried about this problem. We've got an 07 Pilot with 68k on it. It seems, based on what I've read here and on the odyssey forums, that this was much more prevalent with 05s, but that may just be due to the 05s having more miles on them by this point. Who knows?

What scares me the most is that some people have reported a ticking noise incident to the plug blowing out. I've had a rattling/ticking noise on cold startup for the past 20k miles that I haven't been able to pin down a cause for. Hopefully its just coincident.

I guess I'll be heading out to the garage this weekend and making sure all the plugs are in there tight and not loose. Would love to know if the plugs are really backing out THEN blowing out, or if they all just blow out at once.

Fortunately, our Pilot is CPO so we have powertrain until 100k, for whatever thats worth.

[hoorah]

Also, as an aside, I can comment on the anti-seize on the plug threads. If Honda says don't do it - don't do it.

I work in structural aerospace engineering, often times with parts bolted together. Specified torque values are chosen based on the desired axial load in the bolt (or in this case, spark plug), which is based in part on the yield strength of the threads and varies STRONGLY on the coefficient of friction between the bolt and the threads. I can't show you any of our internal documents, but I'm sure some googling could produce something to the same effect.

If Honda says "alright, I've got a steel plug in an aluminum threaded block with no anti-sieze and X coating on the steel threads, my cof of friction is Y. That means I need Z torque for proper fit".

If you go and put anti-sieze on the threads, the torque you apply will be the same, but the axial force on the threads can be wildly different.

Considering most threads, with a nominal torque value, are loaded to around 70% of their yield strength, I'd be very careful not to go over.

Anecdotally, I've been working on cars since the mid 90s, so longer than some, but not as long as others. I've never ripped apart a spark plug trying to remove a siezed one in my time, but I can't speak to others experience.

[NJGuy]

I just changed out my spark plugs this past weekend. When I removed my old plugs, they weren't all that tight. One of them may have been a bit looser than the others, but I couldn't see how they could back out by themselves. Since the corrosion on the threads was minimal and removal was easy, I chose not to use anti-seize when installing the new ones.

I probably have no more experience than hoorah when it comes to working on cars, but I can't honestly say that I've ever run into a seized plug. Besides how often do you hear about seized plugs on stock, properly maintained, street driven Hondas? Sure, the spark plug threads and engine heads are probably dissimilar metals; and combustion chambers aren't a pleasant environment. But I have faith in Honda that they chose their metals and design with the intention of using dry fit plugs that won't get stuck or ruin the head during removal. With some of the other automotive brands, I may be a bit wary.

I have read that when you apply anti-seize or some other type of lubricant to the threads of a fastener, you're supposed to back off of the torque a bit when tightening. This kind of echoes what hoorah just stated. So if you're applying a lubricant in conjunction with less torque, wouldn't the fastener be even more prone to loosening?

Also, if one wants to be a real tightwad about getting as close to the proper fastening torque as possible, he could clean the threads in the head real well with a wire brush or thread chaser. IMO, I don't think it's really needed for these cars.

[Caddyman]

ok so this is my second post i think here. at first i signed up because i had a bit of oil in my spark plug holes when doing a change recently. it is a 06 pilot with 130k on it.

it never had any issues other then a wheel bearing i replaced around 70k

i thought the oil issue was because i read somewhere about the gaskets between the block and head were going bad. as i read this thread though it seems exactly what is happening to my (my wifes) motor. a month ago i had a CEL and took it to get scanned. the scan showed misfires in all cylinders and a bad cat and o2 sensor. i did spark plugs 3 weeks ago. CEL went away, awesome. CEL is now back. I noticed the oil in 2 holes last time i did the plugs so i bought 2 new plugs tonight, removed the 2 coil packs, and there is a tiny bit more oil in there. interestingly enough, the 2 plugs were pretty damn loose, the one was almost hand tight, and i cranked them down pretty good originally (i thought).

so i replaced the 2 plugs and cranked them down good, buttoned it all back up, and we will see how it goes tomorrow. really hoping the CEL goes out, i would like to take it through DMV inspection tomorrow.

[Scooter2525]

So as an accurate assumption, we are seeing this issue in the 05-07 range, after around 60k miles? I have a '10 that has around 30k and would like to nip in the bud to not have expensive repairs like I did on my late bimmer....

[samc]

I don't know if you can say that the problem is on a specific mileage or year set but it seems people are suggesting you just take a 3/8" spark plug socket and check the tightness on your plugs. I haven't noticed anything wrong but I'll probably check my plugs this weekend anyway for peace of mind.

DIY Spark Plug Change with pictures

The DIY calls for 8.6 FT/lbs which is not tight at all. I would just make sure every plug is nice and snug and call it a day.

Edit: So I got off work early today so I checked out my plugs. As said they didn't seem all that tight, I don't own a torque wrench (yet) but I don't think 8.6 ft-lbs is all that much. I loosened and retightened them to "snug."

Here are a few pics of my plugs, they looked fine on an '06 with 63k miles.
And here are the tools I used
-7/32 Allen key
-5/8" socket. You could use the normal spark plug one but that rubber insert made things so much harder
-And your two friendly 3/8" short extensions. The two short ones worked better then one long one.

Just take your time and do one at a time. Again mine weren't all that tight but I think it's just the factory torque rating on these. I feel confident knowing now that they are good to go. And yes the back ones were very difficult to reach but take your time and use one of those helmet flashlights if you have one.

[KKL]

Just did another check on the plugs since January. The back plugs are good. The front ones definitely have loosened up (NOT finger loose, but it did not take much effort to twist loose with a wrench). Will check again in a few months.

[bchaff]

Well, we have a 05 Honda Odyssey with 100,000 miles (we bought it used at 78,000 miles), but just had the same experience with a spark plug loosening, leaving us stranded on the road (on Easter Sunday, no less). Had it towed to the dealer, and when they called back the next day, they explained that the no. 4 spark plug had loosened, destroying the coil and threads. The tech believed he could extract the coil and insert a helicoil to repair the threads, but could not rule out that further damage may have been done. They ended up replacing both the #4 and #3 spark plugs and coils, since the #3 coil was also showing some damage due to heat, as well as the valve cover gasket, grommets, and seals. The total for parts and labor came to $679, which, considering this was from the dealership, isn't as bad as I had feared it might be (that price also included rotating and balancing tires as well as reinstalling as best as possible a rear seat pocket that had come loose). I declined the factory recommended scheduled maintenance service, which includes changing the timing belt; since this was quoted at $1,800 I figure I can shop around to get a much better price.

Just got the car back home last night, and everything seems to be fine, but probably be on guard forever now, checking spark plug tightness and listening for hints of abnormal noise. We asked the dealership if there were any recalls for this issue; they there is nothing they could do at the dealership level, but encouraged us to contact Honda America, to at least let our voice be heard. Hearing some of horror stories on this thread, I guess things could have been much worse for us- but it does sound like this is an issue that is larger than Honda wants to admit to.

[robs]

Was out in the garage tinkering and decided to pull the plugs on my 06 with 80K just for the heck of it. Wanted to see what condition they were in. All of this *BEFORE* I saw this thread.

First things first, they all came out a bit too easy. Especially the front 3. Secondly never in my life have I seen 80k plugs look so good. Boots looked good so I put em in dry. Torqued them to 13ft/lbs.

I'm sooo glad I checked them after finding this thread. I'll give it a few months and re torque them again but man can I sleep better knowing what I know now

[jonshonda]

This just happened to me today. 06 Pilot with 101k. Check engine light w/ VTM-4 came on and I noticed a slight miss at idle....but I had been noticing a slight miss at idle for a month. I know the plugs were overdue, but all other research I had done didn't turn up this issue or any need to change before 100k.

We were 180 miles from home and she started to miss real bad, idle was very rough. Had the wife and 8 month old with me, and the road I was on was very busy and the weather was sh!t. I decided to get to the closest service shop and out of danager. Well, the plug is beat to hell, and the coil too. Threads look to be toast. Had it towed home @ $3.57 per mile.

Gonna present info I have found here to Honda to see what they can do for me.