Ok so I can't find any of my micro SD card readers, so I can't export vids off the boroscope. But everything ~looks~ ok. I took a photo of the boroscope screen and it's so bad it's not worth sharing, but I will anyway. Here's cyl#3 with the missing/blown plug (this is post back-tap and thread chase): https://i.imgur.com/HfN36NE.jpg

Here's the chaser for reference: https://i.imgur.com/midzT4Z.jpg
And the Back-Tap: https://i.imgur.com/vYM47Hc.jpg

I ordered 2 tools to start with, before I jump to an insert. I hit the threads with a back-tap first, then back-tapped a 2nd time, then I hit 'em with a chaser. The new spark plug still won't thread though. So I removed the plug from cyl#4 and tried it in 3 and same thing, it just spins. While I had plug 4 removed, I crudely compared depths. With a good plug, I inserted the plug+socket+extension into cyl#4 spark plug hole without threading it at all, then I removed it and inserted it into cyl#3's spark plug hole. I found the plug+socket+extension went 2-3mm further into cyl#3 plug hole than it did in the cyl#4 plug hole. That told me there has to be material missing from cyl3's plug threads... I don't see any other explanation. I was even able to count threads on both cyl 3 and 4 plug hole threads, and both had 11-13 threads each.

I illustrated a crude MS Paint photo for reference, of what I mean with #3 cyl taking more of the plug+extension length than #4. If anybody has any possible explanations other than "yeah it's definitely missing material/mass that should be there" I'm all ears.
https://i.imgur.com/w7ShfKP.png

At this point the only options I see are 1) install an insert with the head on and see what happens, 2) Pull the head and install an insert myself (if no other issues present once the head is removed), and refresh whatever non-reusable hardware/parts I touch along the way while removing the head, or 3) remove the head and take it to a machine shop.


I have my car parked outside my apartment building, where I've been working on it on a side street. I keep the area completely clean of parts at all times, and all tools not in-use while I'm working are stored away, so my apartment mgmt shouldn't say anything. They saw me today and didn't say anything and I have good report with them so I should be ok from that standpoint. I hate the idea of removing my head on the side of the street in a parking spot, but that might be my only safe option now.


Tiny backstory on this car, for reading material: I had tires installed a few months after I bought the car back in 2018, and the shop told me they couldn't fully align all 4 wheels correctly. They said something about "in order to fully align properly, we'd have to replace ____". I'm pretty sure they they said the subframe but they didn't write it down and I was in a hurry to finish (I was moving out of town the next day lol). Ever since, I've had this idea in the back of my head that it doesn't matter what I do to the car or what I fix, the subframe is messed up and tires wear out in <20k miles instead of 40k-60k+ so it's all pointless. I love and care for all vehicles I own, but that's why I sort of have a "just get a plug safely installed and be done with it until I trade it". 😅
Also, I've done all my work on every single car and motorcycle I've owned, so replacing a subframe isn't a daunting task per se. It's just a lack of means (a clean space to work and an engine hoist or other large tools possibly needed).

 

Just install the insert with the head on using the tool and insert I told you about just make sure it’s a good time-sert insert and it will be fine. The tap is full proof as it uses what’s left of the old threads to guide it in so it will be fine, make sure you put red loctite on the insert so it will never come out again.

 

Yeah I think that's the move. I'll order what I need tonight. Depending where I order from, I may not have everything by this weekend, but I'll update y'all when I finish the insert.
Thanks!

Edit: oh and do you like cutting a new seat for the plug? I see even that $50 kit comes with a seat cutter. I was thinking that might cause shavings but idk yet, I'll research.

 

whatever you do please make sure you use a good insert not the ones that come with the kit unless it’s an actual complete time-sert kit. But the best move is that Amazon tool i shared and just buying the separate inserts elsewhere or from a machine shop. All the best I’m sure it will go fine 🤝🏻

 

Oh definitely definitely. I buy cheap when it's okay but for important parts I always buy nice instead of buying twice.

I snuck an edit in my last post, if you don't mind me asking: do you like cutting a new seat for the plug? I see even that $50 kit comes with a seat cutter. I was thinking that might cause shavings but idk yet, I'll research. Also I have my borescope to check out the cylinder before I crank it after my repairs. I can be sure to find a way to clean it out if it has shavings.

 

I cut the seat on mine but I didn’t go to aggressive, again it’s just a matter of a little grease to catch the shavings. Don’t worry if a couple fall in, they will just blow right out the exhaust. Don’t let that sit in your mind while doing the job because it’s not a huge concern.

 

Cool, thanks, I appreciate it

 

Do you have a link to a good time-sert? I'd like to save the link in case I ever need to install one quickly (hopefully I will not need to) then I will not have to waste time searching.

 

I'll let Cutheal answer for a definite answer.

I found the kit my Fit needs, from Time-Sert themselves. Go to this page and CTRL+F(search) for "IMPORTS" to jump to the kit: + TIME-SERT® SPARK PLUG THREAD REPAIR KITS + spark plug stripped thread repair kits for spark plug problems, thread stripped spark plug repairs in damaged threads in spark plug hole stripped out approved thread repair, aluminum head spark plug repair
You'll see it mentions it has "5 inserts p/n 44111", which you can buy by themselves: https://time-serts.com/store/m14x1-2...lug-p-n-44111/
I found the same part number Time-Sert inserts on Amazon, but they weren't going to arrive until next Friday. So I ordered the kit Cutsheal linked from Amazon, and then 5 of those inserts from the Time-Sert official site^

 

@SavvyFit I'd trust @cutsheal5 all the way on this one. Cuts is a smart cookie. As for that subframe of yours, take some pics next chance you get. Post 'em up! Knock on it and see if it feels solid, ect. With the exception of the CV shaft insulators, rust shouldn't be too secretive I think.

 

Thanks for the vote of confidence! Yeah I'm thankful to have y'all helping me out.

Usually on a car forum, I'm active daily. But my Fit is my first car that wasn't bought as a fun/project car, it's my "responsible" car (as much fun as an engine swap might be); I swore to myself I wouldn't touch anything, not even the head unit haha. I don't have much to contribute to the community for Fits, since I only have experience with the repairs I've done myself on it which are few. I just mention all that to say I like giving back not just asking for help. But since that's all I can do, an extra "thanks" to y'all

 

you can usually just order them from any jobber parts store or if you have a local Machine shop they will have lots of them. Just use one a slightly shorter than the length of the actual spark plug.

 

The only thing I have left to figure out is the seat cutter situation. Specifically, figure out how to cut the seat centered. I think it's with the step-tap+seat cutter+driver combined, but if the cutter follows the step-tap it's not going to make a full clean rotation. So I think it goes over the plug tap as a guide. But since I already cut the M16 threads with the step-tap, the plug tap would spin freely in the spark plug hole now while acting as a centering guide. But my worry is that the plug tap threads could catch the spark plug hole's M16 threads and mess them up, and then I wouldn't be able to install the insert lol. All of this is just due to the Fit's deep spark plug wells. I'll figure it out.

12/17 UPDATE: I got the threads tapped for the insert today. I would have kept going but it gets cold too fast here lol I stopped when I couldn't feel my fingers. All I have left is to cut the seat tomorrow, clean the threads, and loctite the insert.
12/18 Didn't do much work on the car today. I'm going to grind off, or at least grind down, the threads on the M14 plug tap. I think it's what they want me to use for a centering tool (slide the seat cutter over the plug tap and secure the tap to the driver with the little headless socket hex screw), but I don't like the tap threads touching my new M16 threads (for the insert). I don't need the plug tap, just the step tap, so the plug tap is expendable.

12/20 Man, this is a tricky repair. Still working on the seat cutting situation. I know exactly how it's supposed to work now (I kept researching a lot), by leaving the step-tap in the spark plug hole to center the seat cutter. But I can't access the headless hex screw when the driver is in the hole, so I came up with another way I'll try tomorrow. I had a great modification or two I was going to make to the driver and tap, but the tap is high speed steel and I don't have a carbide bit, so that's a no-go.

12/21 Alright, I got the seat fully cut and finished! I cleaned everything really well, including using some 91% iso on the newly-tapped threads with a toothbrush. I'm letting the iso dry for a few hours then I'll run down and install the insert. It's going to be around 1°F for the high tomorrow, -15°F for the low lol so no car work for me tomorrow. Day after tomorrow I can be sure the cylinder is clean and then install the new plug and see if she blows up or runs well.
Unless the iso dries up and magically the cylinder looks different, I think some metal shavings did fall into the cylinder. I'm going to buy a little shopvac and buy or DIY a hose extension, to clean it out I think. Either that or some sort of compressed air. We'll see.
Edit: I got the insert installed today! Red Loctite and all. It installed very cleanly. I stopped making excuses for the torque wrench, dug it out of my closet lol, and torqued the insert to 20lbs. I know Loctite can play with torque values but I'm confident. I'll update again on Friday, hopefully please hopefully with a report my car is running great.

12/24 I finished up with the spark plug and drove my Fit a good 30ish miles today. I'm so relieved. It idles without a problem, no timing noises anywhere, seems to be good to go! I used my torque wrench on the plugs this time, like I should have the first time. They're all at 20lbs now. I checked the other 3 and they had 1/4-3/4 turn left each, to get to 20. So my 'tightening job' might have been the cause of re-failure. But I'm choosing to believe the threads were slightly damaged the first time haha. I'll post when I have pics n stuff on my PC next week; waiting for an SD card reader to arrive. Happy holidays!

 

♫♬♪ I'm baaaack ♫♬♪

I never necro forum threads but since this is my thread and a continuation of the same situation, I figured I'd keep it all in one thread to keep the forum clean. I'm sharing in case anyone else can learn from my mistakes and discoveries.

My insert repair failed.
(Edit: Ok, my repair, the insert, didn't fail per se. The insert came out but I never experienced misfires, nor any codes, and no debris or damage was done. The insert held the proper torque, it only backed out when I tried to remove the spark plug from the engine to check everything out.)

I went ahead and pulled the head this time, I'm replacing all gaskets and seals from the head gasket and up, and doing inserts in all 4 spark plug holes because I'm paranoid about this engine also ejecting plugs from cylinders 1, 2, or 4.
After removing the head, I've been able to determine all the reasons my repair failed.
I'm moving halfway across the States in a couple weeks and am driving my Fit. I hadn't checked the torque since I installed the Time-Sert on cyl #3 in Dec. I was in the process of reassembling the engine last week, after replacing the VC gasket and a handful of others (oil pan and crankshaft were next that day) when I checked the spark plugs. The coil pack wouldn't come out of cyl#3's spark plug well. Not good lol I had to rip the coil pack boot and get it out with pliers. I found the boot had fused to a tiny bit of Loctite from the insert, although I waited a plenty of time for it to cure before installing the insert in Dec. I think it was partly due to being so cold outside, so the cure time needed was much much longer perhaps.

Once the ripped coil pack was removed, the torque was correct on the plug itself, however I had a feeling and I wanted to remove the plug to inspect how the insert was holding up. I began to back the plug out and it was at that moment I knew... something wasn't right lol. The plug had some odd resistance and then started spinning a little too easily. Sure enough, the insert came out with the plug. I noticed the red Loctite was brown and crumbly. It appears the Loctite I used got cooked and fell apart. Now, on to the failure reasons!

1. The biggest reason: I used the wrong Loctite. I've been using Loctite for over a decade but I never realized they were differentiated by more than just colors. I thought "red Loctite" was "red Loctite" across the board. So, I used a common red Loctite, #518 (-65 F to +300 F). The Loctite called for by Time-Sert is Red 6020.
   • I bought some official Red 6020 Loctite and I think I could just thread a new insert back in, followed by the new NGK IZFR6K13 replacement plug I bought this week, and it would probably be fine. But I have the head in front of me so I'm doing it right. But, the other 2 reasons it failed are minor, comparatively, in my opinion.
2. Secondary reason: The insert seat cutter I used is the wrong size for my Fit. This is an oddball situation, and just my luck honestly. For some reason, my Fit engine has a narrower spark plug well than most other Fits. The standard size on Fits, for the width of a plug well, is 0.8". My plug well is 0.75". I did a lot of measuring, now that I have the head off, that led me to this number. Once I had my measurements I was able to confirm. The typical seat cutter for these Time-Sert inserts is pn 44193E. But, there's a revised seat cutter, pn 44193ER, that my Fit needs. It has an O.D. of 0.75". So, the seat cutter I used was actually hitting a subtle lip in my spark plug well and the lip was stopping it 0.25" short of the actual spark plug's seat and the beginning of the threads. This is a photo of the revised/new cutter: https://www.timesert.com/images/sparkplug/44193ER.jpg
   • Unfortunately, it seems to be an incredibly rare seat cutter. I'm going to have to make some calls tomorrow, to multiple websites, and see if anyone even sells this seat cutter. My Google Fu has revealed very very few hits for possible resellers/distributors of this pn. All the "4412e-111" Time-Sert kits (for our Honda Fits) include the regular 0.8"-wide seat cutter pn 44193E.
3. Lastly, and this may not even be a factor, but it isn't perfect: the M14x1.25 insert tap I have and used, gets stuck cutting the new threads before it completely finishes cutting them. I'll include screenshots towards the end of this post for reference.
   • The thing is, I'm not sure if the name-brand Time-Sert insert tap would behave any differently. The only reason it might work better is because it appears the Time-Sert tap has a sharper more aggressive taper to the step-up from the first part of the tap to the insert-sized thread cutter portion of the tap. But I think it still might behave the same way as this 3rd party tap.

I have some reference photos, in case it helps anyone in the future.
This is the measurements, and my steps to record them:


Here's a visual reference of exactly what I'm referring to when I refer to the .8" vs .75" spark plug well width:



And lastly, here's a reference for what I mean about the tap cutting into the head; I stopped cutting when it got hard to cut, and now I see why; I could keep cutting until the insert-sized portion of the tap finishes cutting through, but I think it might hit my valves, and I ain't about that life:



Pros: the cylinder walls are beautiful and flawless, the pistons have 0 valve lash marks or anything, all internal hardware (timing sprockets+guides, camshaft, etc) is all in great shape, and I haven't measured valve clearance yet but that should be ok.

So, my next steps are:
1) Find/purchase the appropriate "44193ER" seat cutter, as well as the Time-Sert tap, and finish installing the inserts. I'm likely going to have to purchase the entire $265 Time-Sert kit, I just have to make sure it has the revised .75" seat cutter included and not the original .8" OD cutter. I'll re-sell the used kit after I'm done and at least recoup $200.
2) Buy a little ShopVac (I don't have a shop/garage) to help clean up the head and block, and make sure debris doesn't fall into the coolant areas of the block.
3) Re-assemble everything, using all brand new gaskets and hardware I bought for everything I touched that's one-use-only (including misc like the catalytic gasket+hardware, etc). I also bought 2 new tie rod ends, mine have busted boots.

 

Welcome back!
Excellent work in documenting everything to help us understand where you're at and why.
I'm certain you'll get this whole matter straightened out, and sorry to hear how much trouble you've run into.

I'd like to contribute some input, hoping that you'll take it as nothing more than that. From reading everything over I'm nervous about the thread tapping issues you're having (been there! shockingly similar, actually.) Have you considered taking the head to a machine shop to have the tapping done rather than buying a kit? I can't imagine the service would cost more than the kit, but I suppose it might be more trouble. Needing an uncommon tap isn't an unheard of thing I'm sure, but whenever something unusual seems to be necessary, my own problems have taught me to have someone else check my work. Just a thought. If you're dead-set on following your current course I'm sure you'll pull it off regardless!

Outstanding job!

 

I'm also on the machine shop camp. That's what we did with my friends GE head after removing. He had them go ahead and put inserts in all 4 spark plug holes and do a valve job. Got another 100k miles out of the car before trading in.

 

Thanks for the encouragement and support, as always! I'd totally be open to taking the head to a machine shop and having them doing it. I actually preemptively contacted one of the highest rated shops in my city a couple months ago and asked them about pricing. Although this would be my 3rd valve job (I've done a head gasket and valve check/adjustment on a VW GTI and a Ford Ranger before), I fully recognize the value of having a machine shop do it. I've actually never interacted with any machine shops before, surprisingly.
The shop quoted me "Rebuilds (valve jobs) are 695.00 plus parts" which was shocking considering my scenario I explained to them involved bringing the removed head (aka ready to throw on the bench without extra work to get to that point for them).

I'll call some other shops today, before trying to find that tap, because it sounds like maybe that price is a bit higher than typical. Maybe another shop can do it for cheaper. I have the head bagged up and in my apartment, I can easily put it in a box and take an uber to a shop. Shops will be a little distance from me but I can hop on a local monorail and get close before Ubering to save a lot of $ for the ride.

I'll see what I can find.

That's awesome! Congrats on you and your friend getting that done. 100k+, nice!

I explained my situation in the text above in this comment, to Pyts. The shop I contacted was way more expensive than I expected but maybe they were pricier than normal. They quoted me almost $700 not including inserts, for a valve job.
I appreciate the seconding of the suggestion, I'll definitely contact a few more shops today before trying to track down the tap I need. Maybe another shop can do it for a more reasonable price.

Also, I bought this Fit in GA, so maybe ours were siblings! 😂 I moved to CO but am moving back to SC in a couple weeks.



Edit; update: I was thinking and ya know... maybe they quoted me more because they're specifically a cylinder head shop not a general/mechanic machine shop? Idk. Google says $150-$200 is average. I'm definitely calling around right now.

 

I get all of that for sure! It was expensive, but not as bad as you were quoted. I believe he ended up in the $600 range, but that was ALL in. New valve guides, new seals, valve job, and inserts. So, he was basically starting over with a completely fresh top end with the benefit of the threaded inserts.

We're also in GA and CO though. Generally speaking, the SE is about the least expensive are in the US for automotive work.

Just info for anyone reading this...The head I'm putting on the L15A1 that I'm building has one hole with weak threads. Because of mine being a build on the wild side with lots of boost, the race shop that did the cylinder head advised against a steel insert because it can create a hot spot in the combustion chamber due to the steel vs. aluminum in the rest of the chamber. I don't think there's any concern with a normal build, but just mentioning it because I though it was interesting. Hoping that mine doesn't eject the plug at 20 lbs of boost because I have a lot of money in that head.

 

That's what it sounded like to me too, despite me only inquiring about a valve clearance check.


That's awesome! This is my DD and I don't want to mod it, but I've watched a lot of videos from boosted Fits. I'm all for fun projects. I bet it's fun to drive!
Thanks for the info about steel inserts in aluminum heads. Good to know! It looks like there's shops and people who are all for quality steel inserts in aluminum heads, as well as people against it. Both sides make sense. Good to keep in mind.


Hey, any advice for finding a good machine shop? Obviously the CNC machine shops are doing things like manufacturing. But there are a couple dozen machine shops on my side of this city. Do you personally look for any particular keywords or qualities or anything, when searching for a machine shop for head work?

Update: Hell yeah! I called up the guy at that head shop I contacted previously, who quoted me the $600+. Talking to him was way better than email. He said inserts would be about 1hr labor ($125) if he can do it "if my tools fit down the spark plug well". He measured his cutter while I was on the line with him and his seat cutter OD is .74", which is perfect! I asked him about aluminum vs steel (I read up on the steel vs aluminum and it makes sense, aluminum expands further/faster than steel, I can see how it could be a problem); he said he'd just do steel on mine since it's OEM non-modded etc. I asked about a valve adjustment and he said it'd be an additional 15mins labor if no parts are needed.
So for <$200 I can swing by, wait an hour or two, and he'll do it all.
Thanks so much guys, this is much better than doing a kit. I appreciate it.
There's city transit from my doorstep to his shop, it'll just take me an hour and some change to get to his shop. I'll go over and have this knocked out tomorrow morning.

 

TLDR (I'll update later) I got my head fixed up by a great machinist.

I've got the head reinstalled and the head bolts torqued down. Working on reassembling.

I missed ordering an o-ring replacement for a part. The O-ring is PN 91302-PX4-004.
Seen in this diagram as part #12:
https://www.hondapartsnow.com/genuin...2-px4-004.html





My move is in 2 days, so I'm going to have to re-use the current o-ring. I never ever reuse o-rings but I don't have a choice. I'm ordering a replacement and will install it after my move. I figure the likely worse case scenario is it leaks a little oil, but I can keep an eye on it when I stop for breaks. Fingers crossed it'll be fine.