Spark Plug Thread Repair Debocale

I stripped out a spark plug thread when replacing the plugs on my Tacoma. Stopped right there and had it towed to a shop in my area to have the thread repaired. Assumed they were going to helicoil it, but the shop ended up just chasing the threads and said it was good to go. I received the truck back and noticed a tick/clank coming from the area of the repair after I got it home. Tick/clank varies with engine speed. I removed the plug and checked the gap, then retorqued it to make sure it does still thread in tightly. The plug does thread in correctly and stay tight. All other plugs are gapped and torqued properly. Tick/clank is isolated to the left side valve cover/spark plug area. Right side presents no such noise. Upon removing the plug from the repaired hole+thread I also noticed that the porcelain portion of the plug, as well as the coil, we damp in what I assume to be gasoline. I really can’t distinguish if it’s gasoline or oil or another substance. It it doesn’t smell like gasoline or oil. None of the other plugs or coils are covered in any substance. Truck has no rough idle. Doesn’t drive any differently.

I’m already taking the truck back to the shop tomorrow to have them check it over again, but I’m posting here to get some other opinions on the matter. I’m not entirely confident that the shop will be able or willing to alleviate the issue and I’m stumped on it myself. Already screwed up the thread. Not looking to blow my engine by ignoring a potentially larger issue that may arise from my negligence.

thank you in advance to anyone willing to help this bumbling idiot

 

When one runs a spark plug tap in, it’s a good idea to put thick grease on the tap to capture any metal shavings and keep them from falling into the combustion chamber.

It’s possible the shop left some slop around the plug hole. Did you get a chance to look at that spark plug when they gave it back before driving home? If yes, and it looked clean then and is now covered in gas, you definitely have a problem. If it’s just grease or anti seize, it’s probably ok.

If you have an air compressor, an air blow gun and some brake or carb cleaner, clean it off really good. If it gets mucked up again, then a thread repair insert is in order. KD makes a good kit with tube type inserts (good) instead of the spring type (not as good). If you don’t feel confident doing the task, have it done by a shop.

 

If there is debris big enough to give that kind of sound in the piston chamber it would of done more noticeable damage by now.
Just my thoughts.

 

I would insert a camera and check for any damage. These engines already have a ticking noise and the left side is louder for some reason. Also if you are like me, you can become paranoid and hear and feel weird things that they were always there but never heard before

 

This is true. I thought that initially as well, which is why I took it all apart again. But after seeing the fluid deposits on the plug and coil I pretty much confirmed my suspicions of something being amiss. Ticks me off too because I could’ve avoided the situation by exercising a little more patience on that plug

 

A while ago I decided to change the spark plug on my pressure washer. It broke where the nut part meet the threads. I assumed it was done but decided to mess with it before I throw it away. I drilled the left over of the plug and got it out. Whole bunch of debris and metal shavings went down over the piston. I inserted a magnet and removed most of it then fired it few times to get whatever I missed out of it. Installed a new spark plug and it has been working flawlessly for the last 6 years. It is a Honda by the way.
I hop the the mechanic shop inspected the cylinder and removed any possible shavings that might fell in there. Again I would insert a camera to check it and check the cylinder pressure. And as others mentioned above maybe the shop lubed the spark with something before they install it.
Good luck bud.

 

Re: Spark plug replacement: This is a related side tip that I was taught many years when I stripped the threads in the head on one of my vehicles: Only R&R plugs on an engine with an aluminum head that is completely cold, i.e.: sitting overnight. The plug actually blew right out of the hole when I was driving it a short time later after the swap. It happened to be the first plug I replaced, and I work slow so dodged a bullet on the other four. The clang and the noise coming out of that spark plug hole was impressive. Explanation given was the aluminum head cools at a faster rate than the steel plug, (which holds its heat longer) and can contract around that plug, essentially locking it in place until the head and the plug are the same temperature. The shop repaired the hole with an insert and all was fine.

Don't beat yourself up too much over this: now you know of at least one other person who had this happen to them. It left a heck of an impression on me and I never swapped plugs again (with an aluminum head) on an engine that hadn't sat overnight. Never had it happen again. YMMV, but maybe it will help someone else down the road.

 

If you are worried something is in the cylinder, get a boroscope and look inside the cylinder for debris. Most shops have small scopes and they even make a bluetooth model for your phone now.

 

At work we got some new machines with Nissan engines. A design flaw we found very soon was the plug threads extended into the combustion chamber by 4 or 5 threads. Combustion would muck up the threads making removal nearly impossible without damaging the head. A trick I learned is to blow the area clean. Just begin to loosen the plug, remove the ratchet and use a T bar with the same socket and extension combination, saturate with wd40, then crank in and out repeatedly to work it into the threads. This trick saved some, some still needed to be helicoiled. After enough complaints and warranty claims, they found plugs with an unthreatened section on the end and started shipping them with those.

Like what Williston said, a cold aluminum head definitely helps. I can usually get away with 30 minutes cool down. But if it’s a difficult one, I’d let it cool and soak overnight.

I missed the part about the noise. Were you able to find the source?

 

The borescope / endoscope are less than $20 on Amazon and work just fine for occasional/hobby use