I recently purchased a 2011 Fit Sport with 115,000 on the odometer. I bought it from the original owner who took good care of it, but he informed me that he had never changed the plugs. While doing some research on what plugs to buy I discovered that some Fit owners have reported loose/blown-out plugs. After reading about this issue I checked the tightness of my plugs and sure enough cylinder #3 was only hand tight and the coil was dirty. I'm glad I caught it when I did and have since ordered new NGK plugs and Hitachi coils. My question is how do I ensure that these new plugs wont come loose? I intend to use a torque wrench and torque the plugs to at least 16ft lbs. I have also contemplated using a tiny bit of high temp blue thread locker but am not sold on the idea yet.I have read everything I can find on this issue and it seems many users recommend different solutions. Any help is appreciated!

 

1) inspect the thread and a plug gasket seating surface on the head (use light, mirror or camera if needed)
2) use throttle body cleaner spray and clean the plug gasket seating area, until all carbon and smoke residue is removed (you can also use rubber 5/8 OD thick wall hose piece to mechanically clean this area
3) tighten the new plug per instruction on the plug package "If a torque wrench is unavailable, finger tighten the spark plug, then use a plug wrench to tighten the plug" (1/2 turn max for Denso brand) Do not use anti seize (people who used it reported increased number of loose plugs).

 

Here is the problem with thread locker. If you ever need to pull that plug again you run the risk of damaging the threads in the head. That is a an aluminum hole and a steel plug. It does not take much over tightening to strip the plug hole. Thread locker might be the same issue.

I would clean up everything and install the new plug to the exact torque spec. No more, no less, Then recheck it at least once a year.

 

that would be a shame if anti seize contribute to spark plug loosening.
in the past for anti seize compound has made a big difference in removing old spark plugs.
hope it's not the case.

thanks

 

I always use anti-seize on plugs that go in aluminum heads. Over the years I have removed cleaned and anti-seized plugs in hundreds of aluminum aircraft cylinders and auto engines.

I did not mention it here because I do not understand why Fits seem to have a problem with loosening plugs in the middle cylinders. Due to my lack of understanding of the problem, I am reluctant to recommend Anti-seize on Honda Fit spark plugs.

 

I used to always use anti-seize (copper) on car / truck / motorcycle spark plugs but not anymore on the FIT ('11 Sport AT bought new). I assumed that the FIT's plugs were installed "dry" at the factory. Once I figured out that my Check-Engine-Light (misfire code #2 & #3) and my Vehicle Stability Assist Light (eventually comes on when the CEL comes on) were due to the loose spark plugs, I installed new plugs (used all of the original vehicle coil packs #2 & #3 were sooty but not melted like some I've seen on the forum). This all started to happen with 37K on the odometer when I started to smell gasoline on start up (March 2014).

Those "dry" installed plugs worked loose again, so I used some of the "blue" threadlocker paste on all four and haven't had any problems since (70K miles on odometer now, so been good for +30K miles). I don't see any downside to using a little "blue" on the plugs to keep them in place.

 

I just got off the phone with my local Honda dealer and they advised me to torque the spark plugs to 20ft lbs. I must admit, I was shocked but the gentleman ensured me that 20ft lbs was correct. Everywhere I read online stated 13ft lbs. as the recommended torque for plugs in our Fits. Can anyone else confirm this?

 

Because the spark plug seem to loosen up no matter what ft-lbs you use and the significant costs of stripping the threads in the head, I would stick with a lower torque level.

I stuck with about 15 ft-lbs and a little blue paste threadlocker and it worked for the last 30K miles.

 

maybe you could chime in to see how hard it was to remove spark plug with threadlocker,
or anybody that used threadlocker. have to check mine soon.

thanks

 

So after doing extensive research on the issue I went ahead installed the new plugs at 20ft/lbs without the use of anti-seize or thread locker. I came to this conclusion for a number of reasons.

-The Honda dealer I talked to recommended 20ft/lbs.
-13ft/lbs was what the plugs were installed with at the factory, and is likely a big reason why the plugs sometimes back-out.
- On a Honda S2000 forum some members were having similar issues with spark plugs becoming loose. One of the members had an extra head laying around and decided to test the thread strength. He reported that at 80ft/lbs he broke the spark plug but was able to retrieve the broken plug. After closer inspection he reported NO thread damage to the head. This leads me to believe that 20ft/lbs is well within the safe amount of torque we can use on the plugs without thread damage. Also, it appears that Honda later recommended that the torque spec be increased on S2000 spark plugs because the original spec was not enough. I have a hunch that it is likely similar for our Fits.
-I decided NOT to use thread locker for a few reasons. Mainly because spark plugs can reach temperatures exceeding what high temp thread lockers is rated for(typically 450*) and the use of thread locker would decrease the plugs ability to transfer heat- leading to premature plug failure.

Before I installed the new plugs I made sure to clean the threads and seating surface in the cylinder head with throttle body cleaner and various soft bristled brushes. I felt that it was very important to remove any carbon buildup that may have gotten into the threads. When I installed the new plugs I torqued them to 20ft/lbs with a freshly calibrated torque wrench. Overall I am very confident I will not have to worry about the plugs coming loose. Although, I do plan to check them in the next 20,000 mile to make sure.

 

Totman - Please report back at some interval (annually maybe) on how it is going.

After I removed and cleaned up the coil packs and bought new plugs, I removed the windshield wipers, plastic cowling / HVAC airbox under the window and eventually the airbox's metal tray, so I had complete access to the back of the engine.

Used a torque wrench (probably no higher than 18 ft-lbs) but no threadlocker. Again #2 & #3 came loose - CEL came on again. So, I decided to use the threadlocker and do the removal / install of the coil packs and plugs "left-handed" & "blind" except for my "mind's eye" without removing the HVAC airbox stuff. So, the plugs with a little dab of threadlocker were tightened according to "left-hand feel". I usually don't do things that way on my motorcycles because of the dire consequences of any failure but I'm the only one driving the FIT and I would immediately understand the issue if it reoccurred.

Anyway, not saying that 20 ft-lbs wouldn't work but I've been good for the last 30K miles and I'm not touching it for now but I do want to adjust the valve clearances (+70K miles on it now without adjustments).

BTW, last fall I took a welding / cutting torch class at the vo-tech and a Honda tech was there and we talked. He stated that the loose plugs was a known issue and guys made a lot of money on it by changing out good coil packs after tightening the spark plug underneath it.

They made a mistake with me when I asked for mine coil pack back. When I could see it covered with soot and smelling like gasoline, I knew it was the plug not the coil pack - jerks.

Sometimes I'll ask a new service rep when should I change my power steering fluid in the FIT. I get all sorts of answers but "never" do they tell me the truth that there isn't any. It's electrically activated. Be careful out there.

 

spike55_bmw - The service rep at my local Honda dealership verified the 20ft/lb torque spec from their online database. My guess is that Honda changed the spec from 13ft/lbs to 20ft/lbs after reports of loosening sparkplugs became more frequent. That's what I understood after reading about other Honda vehicles with this same issue. I would encourage other members here to call their local Honda dealer and see if their service rep also suggest the torque spec to be 20ft/lbs. I think this information is important for others to know if indeed the spark plug torque spec has increased.

 

Totman - Thanks for checking with Honda. The new number is now filed away in my data bank.

BTW, I do agree with you, on a more theoretical basis, that the use of threadlocker will reduce the heat conductivity between the head and spark plug but I didn't use a lot and since all has been good for 30K miles, there has to be enough metal-to-metal between those components to dissipate the heat here in a Pennsylvania-type climate. Maybe if I was in Arizona it would be different.

My one brother tested heat sink pastes as part of a computer processor / heat pipe experiment, so I've seen improved conductivity with pastes but these pastes wouldn't "lock" components together and weren't at engine combustion temperatures.

 

The typical torque value for a used plug with gasket compressed is 14 to 16 foot pounds (Toyota specks, but Honda is the best I know). Any "internal" recommendation is an anecdotal thing unless supported by TSB or a written memo. The service adviser from local dealership tried to sell me ATF flush at 25,000 miles and oil change every 3 months.

 

I changed mine out at about 150k, still original and never were touched since I bought the car new. Put new ones in and tightened them by feel, about to hit 160k. I love this car. Putting Nearly 3k-4k miles a month on now.

 

wow 150k, congrats.
on the new plugs did you use antiseize compound,

thanks

 

I just used the dielectric grease

 

dielectric grease on the coil boot i hope.
to clarify i have always use antiseize on the threads.

thanks

 

Lol, yes on the coil. I did not use anything on the threads, I peeped in the holes and it looked very clean and shiny. No carbon build up in any of the plug holes. I just tighned the new plugs in with a ratchet, just not over tight.

 

My plugs are always loose whenever I check them. For what it's worth, NGK on their web site recommend installing plugs without any lubricant in alloy heads!!