I took the starting motor apart on my 5T D-4 today. The crankshaft had some slop in it and I wanted to see what was wrong before it shelled itself. The rear journal of the crankshaft were it rides on the bearing is .1006 undersize. Sloppy loose. The front journal is .0317 undersize. The crankshaft rattles around in the block like a ball bearing in a 5-gallon bucket. Clearance for Aluminum main bearings is .005-.0085. Babbitt bearing clearance is .002-.0055. The journals for the rod bearings are in good shape .020 undersize. This crankshaft has center points drilled in each end of it. Would it be feasible to turn each end of the crank down say .120 to .150 undersize and make a sleeve that could be turned or ground to bring the journals black to specifications at 1.8120 – 1.8125? A thin sleeve held in place with Loctite 680 or a similar bearing mount material has a super high tensile strength and can withstand an enormous amount of heat. Once the bearing mount has cured the sleeve could be turned true and polished. Are the Journals on this crankshaft-hardened material? A sleeve made of 4140 could still be machined on a lathe and polished to a suitable finish ton run on the aluminum main bearings and be just about as hard if not harder than the crankshaft itself. Will it work and will it hold up being on the journals of this crank. I have the machinery to make these sleeves and turn the crankshaft. Would I be wasting my time?

I lave a John Deere diesel motor in a forklift that has one of the balancing shaft bearings held in place with Caterpillar Bearing Mount. This bearing had a gap of approximately .0125. It would spin quite freely in the block. This balancing shaft turns twice the speed of the crankshaft. It is still working fine after about 3 years. These bearing mount materials that are available now have some tremendous capabilities. Opinions, ideas, suggestions, and comments are welcome. Thanks in advance. bboaz

As you have the machines and the expertise to operate them, I do not see why it would not work. This is one of those ideas that you do not want to send out to the local shop. The original crank is probably just forged and was never hardened. The only thing that I would be concerned with is those centers were probably only used for rough machining and the crank was ground to spec using the actual journal surface. Or at least the gear and flywheel surface.

Rather than turning the crank journals down and sleeving 'em, have you considered turning the crank to clean up and then making new aluminum bearings to fit? The reason I suggested turning the crank is I'd be leery of thin sleeves on a crankshaft. All it would take is no oil in the bearing, sleeve heats up and loosens on the crank and crank starts using the sleeve for a bearing. .Might never happen but I'm a strong believer in the Murphy's Law that states "anything than can go wrong, will, and at the worst possible moment."

If you do go ahead and sleeve the crank, go with at least .003 interference fit and heat shrink the sleeves on rather than depend only on the LokTite. It's good stuff, I probably used several quarts of of the stuff over the years when I was rebuilding heavy equipment parts but I still used a .001"-.0015" interference per 1" of bore to make sure sleeves stayed where they were put.

I don't see why what you propose wouldn't work.
I'd skip the heat shrink proposal though as a 1/16 wall is to thin to get much of a heat shrink.
The crank is plain old cast iron....no heat treat.
The bearing loads are not very severe.

Many a large pump (old) used replaceable sleeves (usually about 1/8 wall) for packing gland wear sleeves, some pressed, some keyed.

Have always been intrigued by the use of tapered roller bearings for the mains on the D17000 similar style pony. Maybe this is a chance to revive the design:)
(Have since read that the reason the roller bearings were abandoned for the aluminum substitutes is that these engines often sat idle to the point where the oil film was lost and rusting became a problem.)

Is the block eaten out or just the shaft? If the block is good I would make new steel inserts to replace the original aluminum bearings and they could be babbitted to fit the shaft after grinding it to clean.
Mike

i made some main crankshaft bearings out of aluminium and also a sleeve over the outside of the crankshaft on flywheel end.I made the one bearing to fit the under size crankand made the sleeved end back to standard size with taper for fly wheel. Have not had any problems .

Thanks for all the input, OldNuc, ol’ Grump, Old Magnet, Mike Mahler, and 560 farmall. Looks like 560 farmall has already done this and it worked. How did you hold the sleeve you made for the flywheel end in place? The block is in good shape. The only thing worn is the main bearings on the crankshaft. I am going to turn a new bearing for the flywheel end since it is only .031 undersize. Polish the shaft on the flywheel end and make the bearing to fit with the minimum clearance of .005. The cam end is going to have to sleeve. It looks like someone has been welding on the bearing surface because it is pitted and really rough. I will be limited on how much clean up I can do because of the bolts that hold the retainer cam gear on the end of the crankshaft. I think a press fit sleeve with bearing mount is going to be my best solution. Make a sleeve with an oversized OD, to press fit on the shaft with a light coat of bearing retainer, then turn and polish back to original size. The woodruff key for the flywheel was wallered out and I have welded it up to cut a new key-way. Again, Thanks for the comments. Brian Boaz

a new seal and sleeve assembly similar to what Farmall described. There is a pusher tool that gently slips this toilet paper thin sleeve onto the flywheel end of the crankshaft. Press fit is all that holds it. A guy at work had it done on his 4020.
You could have the crank spray welded, then ground to original size if bearings are readily available. If not, then I agree to make aluminum replacements is the way to go.

The shaft saver sleeve for the pony crankshaft nose is a CR # SS-99175 (3/4in. wide)
which has a working range of 1.747 - 1.753
Typical nose seal seat diameter is 1.749 - 1.750.

The difference in diameters between journals (original 1.812) and the nose (1.749) gives you about 0.063 in. dia. to play with.

BBoaz, did you try looking or advertize for a good used crank? Just a thought. In central Pa. this Cat dealer, Cleveland Bros. has a Cat used parts store and the # is (814) 342-4210 and ask for Den. Tressler.