torque wrenches can be repaired and adjusted. I used a tester that had a fitting to attach the wrench to and a big dial that read what the actual torque was. We sent it to be tested and certified every couple of years.

 

It seems that this loose spark plug issue is somewhat common on the 2nd gen Fits. I had my eye on a used 2013 sport (120k miles) but now I am not so sure. Does owning a 2nd gen Fit mean I will constantly be tightening my spark plugs to keep them from blowing out?

Does anyone know how well the blue threadlocker will work long term? Could this further damage the threading when spark plugs eventually need to be replaced?

 

That's what I figured. My point is that you need a torque wrench manufacturer to repair and adjust. Not something for Mr Home Mechanic.

 

My sense is that it is somewhat commonly reported on the Internet. Not sure if it is somewhat common versus the total number of Fits manufactured and sold. Also not sure of it is somewhat common on cars direct from the factory assembly line, or somewhat common on cars where someone has monkeyed with the plugs inappropriately. GAFIT has posted that the problem is related to the number of threads on the spark plug. I haven't heard that one before, but it could be correct. However, if it were a plug thread issue, it would be easy for Honda to acknowledge and correct, but Honda, as far as I know, has denied that there is a spark plug issue. At best, they have said it's a torque spec issue — which means there is post-manufacturing human error somewhere.

 

I just pulled mine after changing them 5000 miles ago. All but the number two plugs were loose! Number 2 plug was tightened by me a couple of months ago so it was still tight. Three out of four indicates a problem! I used blue thread locker on them and installed them again. From what I read the blue is the correct type. Don't use red, that is for permanent lock. The spark plug saga continues, I'll keep you posted on how well the blue thread locker works but I have no plans to pull the plugs to check for tightness but I may check number 1 plug since that can be done without pulling the cowling. Best of luck Clay

 

I should mention that I almost didn't check the plugs for tightness. I was just thinking that the number two plug was not really tight when I checked it a couple of months ago. This should be a warning to all of you guys, check those plugs and you may be surprised at how loose they are! I installed the new plugs and tightened them to 25 foot pounds and they were loose when I checked them 5000 miles later! Best of luck, Clay

 

Interesting. As the head threads oxidize and get contaminated, friction rises. So factory torque specs which might be ideal for factory-fresh threads become dicey. The extra friction on the older threads could effectively reduce clamping force (significantly) for a given torque. Anti-sieze coatings included on new plugs could mitigate this, to an extent.

Also, torquing well over factory (revised) spec on a aluminum head risks damage to the threads.

Personal speculation so the views of a professional or specialist would be welcomed.

 

Anti seize might help by sealing the threads from exhaust gases. Any threaded item with anti seize would have less friction and thus be easier to remove. That is what it is its intended use. Mine were brown from escaping exhaust gases so that must be the root of the problem. The thread diameters in the heads must be off a little and that allows gases to permeate the threaded area and loosen the plugs. That is my theory anyway. If your waiting for an official response to solve this problem you will have a long wait! I think thread locker makes much more sense. Best of luck Clay

 

Got one other idea. I'd like to submit for your consideration installing and torquing spark plugs only on a cold engine, same way we treat a valve adjustment.

 

I don't think the torque level is the problem. I used 25 foot pounds on mine and they came loose so just use 20 foot pounds like the new specs sounds good. Need something to seal the threads. Perhaps conductive thread lock would be best? Does it exist?

 

I used permetex "copper spray a gasket" head gasket sealant. It may be a 🐝 to clean out, not sure, but it's.. exactly what you asked for. Haven't checked my plugs since, just the nuts on the coils by hand to make sure a backing out plug hasn't broken them loose, but my engine is whisper quiet.

Available from any autoparts store, most expensive on amazon. cheap from summit racing and ebay.
It's a high temp adhesive version of anti-seize meant to seal imperfections between metal head gaskets and cylinder heads and promote temp transfer.. which it says on the can.
I can't find record of anyone else using it for plugs, but I'm pretty stoked on it.
Also, just so we know we're not alone, F150s around the same age have the same issue. Not enough plug threads, plugs ejecting.
I don't yet know how or if i'll need to clean it out when my change is due at 30k miles (denso ik22s have a shorter life span according to denso)

 

That may be better than blue thread locker. Temp range up to 500 degrees! Blue thread locker works but this may be better still. Nothing noted about electrical conduction properties but its copper infused so that sounds better. Can the plugs be pulled out afterwards though? Please let me know how that goes. Thanks for the suggestion. Best of luck Clay

 

It's likely going to be quite a while before I pull the plugs, but the gasket aerosol lays similar to paint, just sticky like flypaper. I'd be quite shocked if it could stop removal.
I'm not sure what you're driving at in regards to electrical conductivity. To coat my spark plugs (this process is messy) I did something like this



Just getting the threads.

 

Actually I found out you can. Google it.

 

I was referring to the electrical connection between the plug threads and the motor. Blue works fine for this but copper spray may be better because it sounds more conductive to electricity. Testing all of this is a problem since the cowling has to be removed to check the plugs. Even if your plugs cant be removed it may not be a real problem since these plugs last so long. My car had 120k miles before I changed the plugs and had no misfires at that! So you now have 120k miles on your new plugs anyway so why worry about removing the plugs? Best of luck Clay

 

Just adding my experience to the list-

2008/9 GE8 Thailand built L15A7 Manual. 97,000km

Was on a roadtrip, cruising down the country hwy at 110kmph, and all of a sudden hear a clapping sound come from the engine - initially though maybe the accessory belt broke and was flapping about or the undertray broke.

Immediately pull over and the engine is struggling bad and a loud flapping noise with engine light on. I thought either a miss or maybe a bad exhaust leak.

Get it towed to the nearest town's honda dealer because I am hours from my city. The service counter lady say the mechs have diagnosed it as a spark plug coming loose, or even out? and has also killed the coilpack. So they then installed a new sparkplug and a non-genuine coilpack. Show me a print out of the error code, saying it was cylinder 4.

I had replaced the plugs myself around 45,000km and 4.5 years ago - use the NGK advised procedure of doing them handtight and then 2/3 more of a turn to crush the sealing washer thing (i have installed plugs on many cars with never an issue). I guess from now on I will check and torque them every 20,000km.

For a few months before this incident my idle had been a bit low, around 550rpm, and a bit of vibration. I thought maybe a minor miss or an engine mount was worn. Maybe the engine was a little louder too. I was going to look into it, thinking to check the coils.. so prehaps it was actually the sparkplug already a bit loose and not sealing properly. With the new one installed the idle is back to 700rpm ish, but could possibly be the resetting of the ecu too.

 

While you have the time, I'd check everything - all four spark plugs. My #2 & #3 were always the issue.

 

yeah, when i have time i am going to pull out the new plug to ensure the thread is fine... if its fine i might get 4 new plugs and new coils

 

Not sure why you'd be so quick to change the coil packs when they aren't the problem, plus one is brand new. If a spark plug is leaking for many miles, yes, the escaping hot exhaust gases can damage the coil pack and I would change it, otherwise, I'm not sure that they go bad.

After a dealer scammed me and replaced the coil pack ($55 diagnostic, $160 coil pack, $55 labor), check-engine-light came back on the next day (same spark plug was still loose) and they recommended bring it back (more $$$). Luckily I had asked for the return of original coil pack to my car that they replaced. After inspection, covered in gasoline smelly soot, I surmised that it was a leaky spark plug (new to me at the time) and never the coil pack. I changed all of the plugs and reused that original coil pack to prove a point. Everything continues to work fine ~40k miles later, except the #2 & #3 plugs came loose again (~5k miles later), so I used some blue threadlocker, and had no problems since.

 

well i ended up having a look.. and the spark plug that blew out seems to have taken 60% of the thread with it.. I didnt want to bother and risk trying to rethread it. so just got a replacement engine and put it in, and did a new clutch at the same time.