opinions on these 125,000 mile plugs from a 2013. My opinion is not bad. The reason I changed them, was standing behind the car and heard a small skip. Started noticing it didn't have zip it used to. Plug change improved performance.

 

I'm not an expert, Ed, but here's my take. It's good that you changed them out. You've got carbon buildup on the ground electrodes, and discoloration and (perhaps) oil on the threads. I'm wondering why this is happening.

 

Looks like a lean, hot burn. I'm not sure what causes that, I've always wondered. Too much/ too little air? Bad air filters?

 

Thanks for the response. It's my wife's car and she's very easy on the accelator. Don't know if that has anything to do with it. The air filter looked new but I can't remember the last time it was changed. I know looks can be deceiving, (40 year diesel mechanic) I'll change the filter. I checked the valve adjustment while I was right there at them, were all in specs. I was amazed at how clean a 125,000 mile motor was on the inside. Don't know if it's due to advances in oil or engine manufacturing. Probley both.

 

Ask us for an opinion about plugs and then tell us you've been working on diesels for 40 years!
Well! They're lean! But they look even, and modern cars tend to er on the lean side for fuel economy/lean out for coasting. Pair that with a light foot, maybe that's what 120k healthy miles look like. I'd join MC and bet a valve cover leak too by the looks of those threads, but I suspect you don't need to hear that. Sneaky!

 

Sneaky? WTF, i gave my opinion on them and ask for other opinions. My 40 years on diesels doesn't include evaluation of spark ignited engines. I didn't notice the oil on the threads and I wish to thank MC for pointing that out. I did replace the VC gasket when reassembling after valve adjustment check.

 

Hey, I'm genuinely sorry for the misunderstanding. I was just teasing and it came across rough, which wasn't at all the intention. From what you said you've got some serious experience, more experience than the bulk of us here. I took it as a pro half-jokingly asking for input ~ No hard feelings. I do think the plugs look lean, but the consistency and your mention of having checked valves makes me think that's how they're supposed to look at end of life.

I use Denso IK22 power plugs and change them pretty frequently: 10-30k miles. Ive had issues with loosening and have been recreationally experimenting with different means of keeping them good and snug. That is to say when they've loosened, I've often replaced them. I can't say how they'd look after even 30k.

 

Pyts;

Hey, I'm genuinely sorry for the misunderstanding. I was just teasing and it came across rough, which wasn't at all the intention. From what you said you've got some serious experience, more experience than the bulk of us here. I took it as a pro half-jokingly asking for input ~ No hard feelings. I do think the plugs look lean, but the consistency and your mention of having checked valves makes me think that's how they're supposed to look at end of life.

I use Denso IK22 power plugs and change them pretty frequently: 10-30k miles. Ive had issues with loosening and have been recreationally experimenting with different means of keeping them good and snug. That is to say when they've loosened, I've often replaced them. I can't say how they'd look after even 30k.

Sorry I took your comment wrong and thanks for the input.
This was the first plug replacement at 125k miles. None were even slightly loose. I replaced them with NGK which is what they came new. I put moly coat on the threads and torqued to 13ftlbs + a little extra. I wish I had researched a little more and found out about them loosening. Hopefully with my wife driving it most of the time ( I drive it like I stole it) I won't have loosening problems. It don't rack up miles on it like it has in the past.

 

The updated torque for the plugs is 20 instead of 13.

 

@BigEd Pyts was kidding, Ed. This is a friendly, kidding sort of a place. We are also a place that is respectful of anyone who has 40 years of experience at anything. Welcome aboard.

1) I'm not smart enough to know why a lean condition would produce carbon buildup. I would have thought a rich condition would be the cause.

2) Your wife's style of driving may be contributing to the carbon buildup (?). Taking the car to redline regularly may be a way to burn off the carbon. At least, this is what I was raised to believe.

3) 13 ft-lbs on the plugs may not be tight enough (as @Frenzal noted).

 

@Mister Coffee
sorry I took him wrong, we're good now. I may go back and retorque them to 21ftlb in about a month after some thermo cycling. I did torque to 13 + a little because it just didn't feel tight enough, but I didn't want to overtorque in aluminum head.

 

Actually, that is the dry torque, he says he put a coat of moly on there so he should increase that by 20% or go to 24

 

. thanks for the info, I thought moly coat should be used in aluminum. But with all the blowouts maybe blue lock tight would be more appropriate.

 

The molly acts as a lubricant, so if you want to get the same torque you need to add 20%. The spark plug manufacturers recommend not adding any to the plug. As for lock-tight, that has not been generally recommended on these forums. Basically, new plug dry to about 20 torque. Since you added moly, bump that up to compensate for the lubricating action to get the same torque.

 

Wrong way - lubricating the threads results in the fastener being TIGHTER for the same wrench reading. If you are working with a dry torque spec and use anti-seize, you need to REDUCE the wrench reading by 20% or you risk over tightening.

It's important to realize what the engineers are designing for is actually clamping force, which is a function of bolt stretch, and tightening torque is an approximation of stretch but is affected by things like whether the threads are lubricated. There will be more bolt stretch at 20 ft-lbs wet than 20 ft-lbs dry. In critical applications you will note that the spec is a seating torque plus an angle (e.g. 40 ft-lbs plus 60 degrees). This is far more precise than torque alone.

Now, I'm new around here, but not new to working on cars, and in all of the reading I've done the updated Honda recommendation of 20 ft-lbs is WET (e.g. with anti-seize), which means it is equivalent to 24 dry, which is at the top end of the generic spec for the thread pitch of the required plugs in an aluminum head. Honda's original spec was 13 ft-lb, and I've seen conflicting documents saying that both wet and dry. The difference in clamping force going from 13 dry to 20 wet is huge, and quite possibly (to me - likely) Honda's response to ejecting plugs.

I am referring to the picture I insert below, where the PDF service manual is shown on the left, and a fresh printout from the dealer to a forum member is on the right. It shows the updated Honda spec of 20 ft-lbs WITH a "small amount of anti-seize".

EDIT: to make things more interesting, apparently if you purchase genuine NGK plugs for this application NGK includes specific instructions to NEVER use anti-seize. Not going to lie, finding this all a little frustrating. In my situation, I was all geared up to at least check plug tightness prior to heavy winter and replace in the spring, but it turns out that my Fit had plugs replaced by a dealer last year so I'm probably not going to do any of it prior to heavy winter.

 

Yup, I got it backwards Good call!

 

Idon't know much abt my (sad). But, where is the carbon?At tips as shown in picture?