I would like to say that this story all started with a little problem that just happened to appear one day, however that was not the case. My truck has been a mess for some time and through my own limited abilities I have been trying in good faith to keep her running well. Of course my skills are meager and as I've been finding I have the apt tendency to do more harm than good. So the other day I thought I could perhaps take a more careful look at some maintenance I had performed several months ago to see if I could find reasons for the rough nature of my beloved truck. My first thought went to the spark plugs. I had replaced plugs, wires, and distributor cap all around the same time and this had improved the truck a great deal in some respects, but had not solved all issues. However, at the time I was satisfied with the results and so left well enough alone. Well as I learned upon inspecting the plugs, all was not well. My number 4 cylinder's plug was not screwed in very far. In fact, it took about two full rotations to bring the plug out. Something was very wrong. Upon further inspection, I couldn't turn the plug back in nearly all the way. Obviously I must have been rushing the job last time I changed plugs, cross threaded this one and left it as good thinking it was in all the way.
Now I did know that there was a way to re-thread spark plug holes, but I had never investigated the methods, nor had I thought that it could be something within the confines of my abilities. A little internet searching turned up a few different companies that made "kits" for thread repair. The first one I found was prohibitively expensive and other was reviewed with much skepticism by a Toyota internet forum. In turn, I decided to simply check the local "O'Reilly's" for what they might have to offer.
I should step back for a second and say that I was not optimistic about this repair. It seemed like something I could really screw up. Images of metal chips from the die falling into the cylinder and doing some serious internal damage were on my mind. However the instructions for this little kit were very simple and straightforward and made no mention of this danger except to say that chips should be cleared from around the hole prior to withdrawing the cutting die. Upon reading this I sought out an old vacuum cleaner with hose attachment and a pack of q-tips. I promised myself that I would not do this job in haste and if at any point I felt myself rushing, I would stop immeadietly and come back to it later.
Equipped with the proper tools and mental state I began work. The process was simple enough. The step die was able to grab enough of the original threads to get started and the vertical alignment was satisfactory to my eye. After cranking away for something like 15 minutes, the die finally bound up and stopped, telling me I had gone as far as I could. Then the vacuum came into play and I methodically sucked up every chip I could manage. The q-tips were moderately helpful, but the vacuum was certainly invaluable. When I was satisfied, I withdrew the die slowly, and upon freeing it from the shiny new threads I realized the die was magnetized and doing a wonderful job of hanging on to a ton of chips. One last job with the vacuum and the hole was clear. Now began the tricky job of properly seating the insert to the desired depth without damaging any threads. I screwed a new spark plug lightly into the insert, coated the outside threads of the insert with RTV and placed the whole package on the end of a sparkplug socket and extension. The threads matched well and I didn't make too much of a mess with the RTV, but the one dilemma I faced was how to remove the sparkplug without simply pulling the insert out with it. Through trial and error and a quick snap of the wrist to break the spark plug free, I found I could tighten the package down and then the friction of the RTV held the insert while allowing the sparkplug to be withdrawn. Now I was looking at a brand new set of threads for a previously ruined spark plug hole. Per instructions I used the "seating" tool and a hammer to mush the top of the insert just a little bit. I didn't really understand what this did, but I'm guessing it helps to prevent the insert from loosening in some way.
I stepped back. Was that it? Nothing failed so far. No obvious screw ups on my part. However, the RTV required 12 to 24 hours to fully cure before I could run the vehicle. The morning came, I walked outside, slipped the key in the ignition, turned, and the truck lept to life. I heard a sound I had never heard before that I think came from the starter. I was unable to replicate the sound and wrote it off. After the truck warmed up, my idle was steady and the truck had a bit less shake. After a short drive without any ugly sounds or failures I proclaimed the repair a success. It was certainly a portion of my troubles, but the truck will still need some tweaking. I have yet to check the other bank of cylinders for spark plug issues, deciding instead to focus on one problem at a time. That will be my next area of focus, one that I actually look forward to now that I've gotten to experience a little bit of satisfaction in my work.
