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Well, it happened. Two miles from home today, on a quick run to the grocery store, truck blew a plug. Scared the crap out of me when it happened. I was under very light throttle, pulling away from a red light. Driver's side, 2nd cylinder from the back. Thank the good Lord this didn't happen 1-2 months from now, 200 miles from home, deep in the forest on a camping excursion.
I found the COP (broken at the screw/tab location), and the spark plug still in the engine bay. Based on inspection of the plug, the threads do NOT appear to have stripped. Appears to me that the plug simply loosened over time, and just kinda worked its way out.
At this point, based on the status of the old plug, I'm thinking of buying a new plug, a new COP, screwing in the new one at precisely 23 ft-lb torque, and carrying on as normal. I'll also be pulling the other 9 plugs, and re-torque'ing to ensure they're in there good and tight.
Am I missing anything. Should I dig into this any further?
Now that the Masters is finished, and I'm thinking about this a little more, it occurs to me that the look of the spark plug could have very little to do with the condition of the head.
Peering down into the head, I can definitely see threads. I don't have a fiber optic camera for a good "professional" inspection. But I do have a little LED light on a ~18-inch extension and there's threads present, no doubt.
However...my best hope for simply screwing in a new plug is not to be. I can get about 1/4 turn and there's resistance. Dang.
I don't really want to brute force the new plug in there -- that goes against my best judgement. I also don't know if anything fell into the cylinder and trashed the cylinder wall or valves yet. Gotta get the plug hold fixed and THEN test for compression.
Probably the last thread got pulled a little when it blew out. Get the proper tap and try to chase it. You'll have to be as straight as possible to start it. If there are good threads you should be able to torque it down and go.
I agree with your presumption on the last thread getting a little whacked. So try to chase the threads first (and chance not being totally straight when I start), and then torque in the plug? Or just try to torque the plug in now?
I believe I can feel the spark plug "bite" at the first thread, but then it gets resistive after 1/4 turn. I am so tempted to take a wrench to it and see what happens. But also trying to keep a cool head (pun intended) about this.
I could agree with the tap idea. I would also be tempted to put a wrench to the plug as well. Either way further damage is possible. If it were me, Id probably add a little oil to the plug and slowly try it with a torque wrench set at 10 ftlbs. that way you're not putting anymore than that to it. A tap can cut a new path easier and ruin it for you requiring a Timecert.
Try a "thread chaser" first. They're made for this job of cleaning out damaged threads and usually can work a bit better than a machinist's standard tap. They have special taps just for spark plugs that are not the same as a standard metric tap.
I'm dropping by the auto parts store on my way home to grab one of these. Will give it a good coating of grease to catch any metal filings and try it out. If this works, I'll have saved myself $200-500.
According to their website, my store does indeed have this part. I have to stop by there on my way home anyway so I'll find out for certain in a couple of hours.
Considering I've never done a Timesert procedure previously, I'm a bit nervous about doing it myself. Then again if I do it, I'll know it'll be done correctly (or at least to the best of my ability). I've called 3 shops today who claim to have successfully performed the Timesert many times.
How much "rent" are you looking for yours? Shoot me a PM.
Im curious if you've changed your plugs since owning the truck.
I changed mine out the first year I owned it for fear of the same thing, but not sure if the originals are more prone to blowing than properly installed replacements
Yes, I changed out the original plugs about 2 years ago. I installed the new ones with anti-seize and torqued with a wrench.
Since swapping out my originals, I've read that some guys torque theirs down once, then back out until loose, then re-torque a second time. I didn't do that. But maybe I will this time.
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