Ok, so you can read the rest of the thread and see the battles I went through. After having the crank bolt break, the dealer replace it but not torque it down right so the bolt backed out, then trying to re-torque the bolt myself with rusty, worn threads and having it back out again, here's what I had to do:
That's my crank nose after one broken bolt and two incidents of bolts backing out. Not very promising is it? Can anything save it? Yes.
I bought a Time-Sert. Elsewhere in the thread I mistakenly called it a Thread-Sert, but Time-Sert is correct. These are sort of like Helicoils in that they are meant for replacing stripped threads, but they are different in that they are a solid piece of metal instead of a spring, and they must be sized to match the bolt in all dimensions. If you have a stripped bolt in something else, you will have to measure for yourself. If you have a stripped bolt on a 3.5L Montero V6 (or whatever else used this same crank shaft / bolt / harmonic balancer combo), then you need Part Number 1415H.
The bolt is an M14, 1.5 thread pitch with 28mm of total threaded length that goes in the hole. This is why the Time-Sert can handle the torque and Helicoils cannot. Some Helicoil style inserts will try and tell you they can take whatever, but the better ones do publish max torque specs, an they are somewhere around 20-30lb-ft. No good. When I called Time-Sert, I was able to talk with one of their engineers who went way more into fastener science than I would have ever intended to venture myself, but the simple answer is that these kits will hold as much or more torque than the original metal without slipping if you take your time to do it right.
There you can see how the threaded sleave perfectly matches the threaded length of the bolt. That precision is key, and it fits with all the other precision parts of the kit. I keep saying kit, why? Well because it has everything you need to do the install except for two things. I will get to the two extras you need in a moment. Inside the kit though, you will find a 37/64ths drill bit, a counter sink tool, a precision tap matched to the insert's outer threads, an install tool, a guide for holding the bits when you start them, and the inserts (a new kit has 5). They are very well made pieces, and the use of them ended up being much simpler than I though. Still, here's the new kit;
I said two things were missing. The first is relatively cheap and easy, heavy cutting oil. I know some people use WD40 or some other lubricant when they are tapping a hole, but you will have a better time of it with the purpose made stuff. I spent $10 because my local Ace only had a big jug of it, but a little bit is all you will need at each step. The second is some type of T-handle or driver for each tool. All the pieces have a square shank, but you will find most tap T's can't fit their girth. The good news is that standard 12 point sockets will fit them just fine. I used some 3/8ths drive sockets (1/2, 7/16 and 3/8 I think) and a sliding/T-handled ratchet I picked up at Harbor Freight for like $6 or so. I suppose a regular ratchet could work too, but to keep things aligned I thought it best to have something I could grab on both sides of the bit to keep the force centered.
So to start... First you have to drill out the hole. I stressed and stressed over figuring out how to keep things straight as you have seen in this thread. It turned out to be completely unnecessary. If your threads are worn like mine; worn to non-existant the first mm or two, and getting progressively better the deeper you go, then the bit will bite in straight and true without much effort. Still, to be say, I temporarily JB welded the included guide to the crank washer (I had bought a new one to be safe) to get more surface area against the crank nose. You drill at least 29mm into the crank, so it is definitely a good idea to stop the motor from turning. You can do that by blocking the flywheel teeth at he inspection hatch, the rope trick, or any other way you know how. Just be aware that around half way through you will start to have the engine turn if you don't do something. After drilling, the hole looks MUCH better with fresh metal exposed.
After drilling, you counter sink the hole. This is because the insert has a bit of a lip to keep it from going deeper even if you drilled the hole all the way back (the crank has a 38mm deep hole typically). You need a completely flat surface on the nose of the crank, and Time-Sert has thought of this. The counter sink will stop at exactly the right depth for the insert lip, and the tool fits the freshly drilled hole perfectly so that it is even and clean.
After countersinking, then it is time to tap. Each step up till now, I have used a light little bit of oil, and cleaned the hole with brake cleaner to blow out the metal bits. Before tapping, I used A LOT of cleaner, then dunked the whole tap (except for the shank) in the oil. I also had to remove the JB welded spare washer from the guide at this point since the tap will not fit through the washer. Go slow. The tap cuts very well and centers fine, but I would hate to strip any of the new threads from the get go.
I am sorry, I do not remember which step that is there, but I thought it might show better how I was doing each step. Yes, I drilled by hand. Besides not having a drill that would hold it, but also I wanted to be sure things went slow and didn't get over-cut. Metal can't be replaced after all. Once the threads were cut, test fitting the insert showed the precision of the tools and their sizing. The insert threads in by hand tight, but very clean and smooth. I took it back out and used the highest strength thread locker on the outer threads of the insert (taking care not to get it inside) and screw it in by hand. It will go in all the way without too much issue.
With the insert in, I put just a drop of cutting oil on the tip of the install tool. It threads in to the inside of the insert again with clean precision until the last 2 or 3 turns. These last turns are what permanently sets the insert in place. The back en is not fully formed internally. The instal tool forms the last threads while also expanding the metal of the insert into the surrounding metal with great force. I personally let the thread locker have all night to set up and harden before I put the truck back together. Not sure if that was necessary or not, but I wasn't taking any chances. It looks much better now doesn't it?
At this point, if you were careful and took your time, you will have what amounts to a brand spanking new crank, at least as far as the bolt hole goes. Put it all back together and make sure you do get to 135. If you want, you can put some thread locker on the bolt too. Just make sure there is no cutting oil left both when putting the insert in as well as the bolt because thread locker will not set right if it is contaminated. That should be about it. If you have any questions, I will be happy to answer. Since the kit came with 5 inserts but I only needed one, I will be selling it at a savings. See the for sale section, buy it, then pass it on at another discount. The way I see it, 5 of us could all fix our rigs for around $25 a piece this way. No matter what though, good luck and happy wheeling!
Ok, I just added the kit to the For Sale section.
Please PM or call me (623-565-8432) with sale related questions, use or experience related questions post up in this thread.