Tapered Seat Spark Plug Horror

[awesomeissquid]

@ramangain I did something similar and took some old fabric and wrapped it around a screwdriver. I used that to clean out all the funk and then used a small hose on my vacuum to get all the way into the hole.

I ended up reinstalling the new plug I pulled since I need to order all new ignition coils. I figure when I test the engine and listen for any noises I can determine if I want to replace it or not. After finishing the drivers side plugs I chickened out on starting the engine. Tomorrow after some rest I’ll give it a once over before I crank it.

I am still curious about which part I would have to replace to get this back to factory condition. Looking at more parts diagrams I feel pretty sure this would be cylinder head. Is that something I could pull off another engine and then swap in all my other associated parts?

 

[LongHaulCruiser]

I don't think you need to go to the trouble of replacing the head. When I read that you were able to torque the spark plug to spec, I thought good for you. Clean out all the debris you can and put the plug back in. Drive it. Check from time to time to make sure none of your spark plugs have loosened up.

 

[awesomeissquid]

Appreciate the confidence. I am feeling the same way and was more just trying to cover my bases and also trying to better understand how the engine parts come together.

 

[ramangain]

It looks like there is more old spark plug metal down there on the lip of the spark plug hole. That is what is denting the crush washer of the new plug. Use your telescoping magnet to block the hole into the combustion chamber, and use a pick tool to loosen that last bit of scrap metal. After that, if the plug seals and torques down properly, job done!

 

[gatormark91]

Masking tape wrapped sticky side out around a wooden dowel is great for retrieving many things. And if any of it gets stuck in the cylinder, the tape and wood are soft and combustible.

 

[sacman]

I think that you're ok if the spark plug was torqued down to spec. The likelyhood of debris getting into the engine is there but if you are able to put a pickup magnet down the hole gently I think you should be able to pick up a lot of them since they are also metal. I would keep an eye on it to see if the plug come out after a few hundred miles.

 

[Braden620]

+1 on the time sert, used a few friday. I love em!

 

[awesomeissquid]

Quick update on this:

I reached out to NGK about the plug I pulled from the engine since it looks like a taper design but the model number IFR6T11 only lists a gasket design on their website. The representative confirmed that the model number is for a gasket type plug and that it looks like the gasket has been flattened from being over torqued. I plan to try to remove what may be the gasket to confirm that is the case.

 

[Malleus]

I'd worry most about what fell into the cylinder and is sitting on the piston. The only way you'll really be sure the cylinder is clean is to pull the head. Even the smallest trash will score the cylinder walls. Just my 2¢.

 

[awesomeissquid]

@Malleus I had the same fear. When I pulled the plug for the second time with the borescope I was able to insert it through the spark plug hole and look at the piston head and surrounding wall. No debris was in there. I am going to switch out the plug for a new one with a fresh gasket and take another look before I start the engine just to be extra cautious.

 

[Malleus]

It's too bad someone doesn't make a vacuum the size of the borescope...I'd buy one for sure. Good luck.

 

[awesomeissquid]

Small vinyl tubing and an adapter and you are off to the races. Here is the setup I used for all of them just to be on the safe side.

In other news, since I was already procrastinating a bit I decided to see if I could remove whatever was on the spark plug. It got mangled a little, but the concave bit screwed off and revealed the crush washer underneath. Any ideas on what the concave bit might be? Its magnetic so my guess is that it's the top part of a helicoil or time sert that got installed and broke off when the spark plug was torqued on. Maybe the insert (helicoil or time sert) was not fully installed and the top snapped off?

 

[Braden620]

Here is the biggest Time Sert I have (M12x1.25). Spark plugs gaskets don't have threads and are far more ductile that the what you're holding. That lip around the top edge sure does look like part of an insert.

 

[awesomeissquid]

Weekend Update:

I borrowed a higher quality borescope from work to get a more detailed look at what was happening in the threads and to check out the piston head some more (video links below since I couldnt figure out how to upload them). I can conclude that it was a time-sert installed which backed out and then was torqued down upon which broke some of the threads and the top off of it. I reviewed the maintenance notes I received from the previous owner and it seems that this cylinder had the ignition coil replaced in 2017 about 37k miles ago, so maybe they retorqued the spark plug then and that started this whole thing.

Looking at a sideview of the threads it appears that 4x full thread rotations remain on the time-sert which must be all the spark plug was held in by. The piston head appears to still have some threads on it. I am keeping my fingers crossed that they are just sitting on top. I am going to attempt to remove them with a magentized coat hanger and the vacuum tube.

As for the broken time-sert, does anyone have any ideas on how to remove the rest of it with minimal damage to the remaining threads in the head. I figure if I can remove it, a new time-sert can be installed to restore the full thread holding power. Bonus points if it can be removed without pulling the head cylinder off since I really don't want to do that. I wish there was some sort of tool that could expand against the time-sert so I could unscrew it that way.

Piston Head Video
Thread Side View (Piston to Spark Plug Tube)

 

[MJK]

I don't think I would mess with it, but....

If you elect to I would try and loctite a plug to what remains of the timesert to remove it. I believe the correct replacement would be M18 x 1.50, in whatever length you need.

If it got to the point where I needed to remove the head, I would replace the head rather than the timesert. But, I have trust issues.

 

[awesomeissquid]

Interesting thought to run it as is. I guess I could increase my inspection schedule to ensure it isn’t backing out .

Also, the loctite suggestion is great. I could see that being a good option if it comes to it.