1200 Lives (Previous 1/2 pwr w/ clank
- Thread starter SteveV
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The story starts with the block upsidedown on the floor of my cellar. Outside is one of the snowiest winters I've seen in 5 years. Disassembly reveals that diesels don't leave much of a cylinder ridge; the pistons came right out when disconnected from the crank. Holding the two peices in my hands was a harsh moment of reality. Off we go to the dealership to order the new crank. Yep, there is one showing in the computer inventory. Two weeks go by, and the prepaid part turns out to be a phantom, none available with no hope of ever getting one. Here's your refund! I did keep the gaskets for the pan, head and front timing cover for fairly short money but there is no need for the replacement bearing liners. Here begins the story of the crank repair.
scruffy
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And now for the rest of the story????
The break was irregular through part of the number 2 rod journal. All but a quarter of the rod journal bearing surface is unaffected by the ragged break. The first challenge was finding a way to clamp the two pieces together so a pilot hole could be drilled to keep the drill bits aligned. A 4 inch angle grinder was used to make a flat surface on the sloped space between the #1 and #2 journals. While clamped up, the two pilot holes were drilled from the flywheel end for the two 1/2 in x 3 bolts that were used to permanently bolt this beast back together. The bolts enter the journal from different directions (see attachment that follow) with a clearance hole near the bolthead and a threaded (read tapped) portion on the other side of the break. So when unclamped, each broken half of the crank would have one tapped hole and one clearance hole.
Attachments
The cast iron drills pretty good but a dull bit would heat the iron and turn it hard as granite (3 or 4 bits were hurting after those holes). The ground flat (for clamping) also left a drill eating hard section about an 1/8 in thick. The flywheel end has a thurst bearing that requires the bolt head be recessed in a counterbore. Since the 3/4 counterbore required was a special order and came with a 3/4 shank that my 1/2 drill chucks couldn't handle, a 3/4 drill bit was purchased (with a 1/2 in shank) and the counterbore shoulder was formed with a 3/4 hole saw. It was a bit tacky but it worked.
Attachments
The first time the crank was bolted together in installed in the block, it bound up when turned by hand. The solution for this was to remove the crank and loosen the clearance portion of each bolt hole by drilling it slightly larger. After doing this and cleaning up some burrs, the crank spun freely and ran true in the block. One final removal of the crank, the holes, bolts and crank where cleaned with brake cleaner, then locktite red was applied to the threads and metalic epoxy was applied to fill between the bolt and the clearance portion of its hole.
Attachments
The machine has been reassembled with new gaskets and the front timing cover seal had to replaced (it was destroyed by the crank flopping around). At this writing, there's about 1 hr on the rebuild with no changes in noise or behavior from the time it was first started. The injector pump and injectors were rebuilt after breaking the crank but before the teardown so the engine behaves differently to me. Yup, it runs at PTO speed with a bit more vibration probably from my grinding the flat and unbalancing the crank.
Attachments
Von
Veteran Member, Advertiser
OK guys, who wants to start a pool and bet when it will let go? I say within 15 hrs. on the clock. This is not to be mean or anything Steve, Its just that there is a reason that cranks are hardened. With the toque that a 2 cyl. diesel puts out I don't think it will hold for too long. Hey I hope for your sake I am way wrong, but we will see.
RobS
Super Member
Yeah, I'm with Von on this. Normally I'm a pretty optimistic guy, but in this case I think even 15 hours is overly optimistic. There is a tremendous amount of loading, both straight forces and torques on a crank not to mention vibrations. Did you check into a professional repair? I don't have a clue about it, but a decent automotive machine shop could tell you if it could be welded and reground. Good luck in any event /w3tcompact/icons/smile.gif
Von
Veteran Member, Advertiser
Rob,
Yeah, I don't think it will last too much longer. Thats why I said it would let go within the first 15 hours.
Steve, If you are going to sell it, I hope you tell the new owner of the repair. If not I think you would just be setting yourself up for a law suit. Anyway best of luck with it.
Yeah, I don't think it will last too much longer. Thats why I said it would let go within the first 15 hours.
Steve, If you are going to sell it, I hope you tell the new owner of the repair. If not I think you would just be setting yourself up for a law suit. Anyway best of luck with it.
