Powerbuilt 14mm Back Tap Spark Plug Thread Repair Tool, Straightening Tool, Motorcycle Spark Plugs, Repairs Damaged Threads, Collapsible Design - 640811

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!

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).

Worked very good save a lot of money. Easy of use was fantastic. Happy 😊

This thing helped me out a few times. If you work with small engines this is a good tool to have for the customers that cross thread spark plug holes and you don’t want to have to take the head off to tap it out. Seems to be built pretty well just take care of it and use it properly and it should last. Definitely recommend it.

This is a good tool for the money. If the threads for your spark plug are chowdered up, you basically have three options: a new head (rarely needed), drill out and tap the head for a helicoil (probably the best option), or chase the threads. If you make sure that you can clear the piston when using this tool, and clean up any debris before you install the spark plug, this works as a good, comparatively quick, low cost first option. If you've only got half (or less) of the threads left, you can at least use this to install a plug for a drive to the mechanic for a proper helicoil insert, saving $100 on a tow bill.The only "flaw" I noticed when using the tool is that once it's greased up, the center rod that pulls in the cone shaped plunger wants to spin so it was impossible to fine tune how deep the threads cut. The only way I could get it to tighten was to just fully pull back on the knurled nut, tighten it down as good as possible, and chase the threads in one pass. I got lucky and it worked out. I would like to see something like a slot in the rod with a roll pin to keep it from spinning, but considering it did the job I can't complain too much.The only other issue I had was with the length of the tool, and that was only a minor issue for my situation. Because of the location of the spark plug hole it was difficult to maneuver to tighten the nut with the tool fully inserted. 2-3 more inches would have really been helpful (true on many levels). I was eventually able to mess around with some long handled needle nose pliers to get it set (also true on...). Had I been working on a spark plug near the firewall I don't think this tool would be long enough to work.