Powerbuilt 14mm Back Tap Thread Repair Tool - 640811

I was hesitant to order because there were some negative reviews, but since I'd already stripped the threads in my generator's engine and needed something, I went with this one. And it worked perfectly.If you want great results, take your time and play with the thing. Learn how it works. Snap it fully open, pop it closed again, slowly open it, all that stuff. Work with it. First of all, you want to make sure it works before you put it in your engine; if those expanding thread pieces are going to break off (like one review said), then you definitely want that to happen OUTSIDE your engine! But you want to play with it to see where the knob engages, where the expanding plunger stops spinning and starts gripping and spreading the threads outwards, etc.Second, do NOT put grease on the expanding plunger. You need friction there, you want it to grip the inside of the expanding thread "leaves" or whatever you want to call them. Grease up the threads plenty, you need that grease, but don't put grease where it can get on the inside of the leaves.Third, go slow, take your time, and as you're removing it and cutting new threads, if it suddenly gets a whole lot harder to turn, don't just force it through. Back it off a little. Reverse it and thread it back in maybe 1/4 turn, and then reverse it again and try removing it again; you will probably find that it works smoother the second time it traverses that same spot. What's happening is that as it's cutting new threads, chunks of metal are getting caught in the threads and binding up. You don't want to just force your way through that. By reversing and backing up, it lets those chunks of swarf get caught in the gaps between the four expanding "leaves", getting them out of the way of the threads, so it's much smoother to remove the second time you try to pass that same section.Fourth, go in a few passes. Don't expand it fully the first time you try it! Do like the instructions say, expand it some for the first run but not all the way. For my first run I tried to make the grooves between the leaves basically parallel, so the threads were pretty much even over the whole tool. Remember how many turns of the screw it takes to get it to that size. Then minimize it, grease it up, put it in, expand the leaves to that same size by backing the screw out to that same size, and extract it slowly from the socket. Then clean it up, get all the grease off it (especially between the leaves, where most of the swarf will be), and then split the difference between the expansion size you had (where the grooves are parallel) and the fully-expanded size. Find that middle ground, remember the number of turns of the knob necessary to get it to that size, and then minimize it, grease it, etc, same a the first pass. Then clean it off and grease it up and get ready for the final pass. Put it in the hole, hold the tool down with a wrench of the right size, and yank the rotating knob as far out as it will go so the leaves snap fully open, and then extract it once again, backing off when encountering higher resistance and then going forward again.Once you get it fully removed that third time, you should have perfectly functional threads again in the spark plug hole. I can tell you I did.For getting rid of the grease, I used the red can of Brakleen (chlorinated), and it washed the tool spotless. I hope to never use it again, but am very glad I have it. Really saved my neck (and my generator).

This tool saved me a lot of money. You have to be patient though. Keep cycling through the process. Also another tip: once you finally get the tool to the fully expanded setting, and it will back out well, then I suggest that you slowly work your way out by going back and forth. So make 8 turns out and 6 turns back in for example. This way you clean up the threads in both directions. Lastly, I did all my work by hand. Only once did I put an open end wrench to back through a sticky spot. And I only did that after I had already made a pass with the tool fully expanded. Baby steps and lots of patience needed. This is not a brute force process. The end result was a ok threaded hole. Definitely not like a freshly tapped hole in the end. I also did something that I didn’t want to do. I put a fine line of anti seize along the threads of my plug. I just felt there was too much friction . Check out my before and after pics.

Worked great! I had one spark plug that wouldn't fully seat on a 74 VW I picked up. Since the head is aluminum I didn't want to try and force it. Ordered this and it worked great in cleaning out the threads. Spark plug seats all the way and snugs up as it should. Saved a lot of pulling the head!

This little tool is worth it's weight in gold! Had a JD mower come in with a cross threaded spark plug hole. This tool goes in with some grease to collect any shavings and lubricate. Make sure it's straight. You can feel when backing it our when it engages the threads by hand, and it will turn smoothly. Gradually tighten the screw and back it out by hand until it starts to get tight on the damaged threads. Use a wrench and gently bring it out. Takes about 3 times, each time adding a little more tightness. when you have the tool fully engaged, it wont tighten up anymore, you should still be able to back it out by hand until it gets to the damaged threads, then work it back and forth gently with a wrench. It'll take some time. Don't force! It is doing it's job. You will feel it getting easier each time you turn it back and forth. After you have it out, clean up and hand start your spark plug and you can tighten up to the gasket by hand, then snug properly with a socket. Done!This is a very good tool, works well. Note: Just don't get too much grease on the cone shaped wedge that expands the threads. It needs some friction in order to tighten up and expand the cutters.