841D broken crankshaft

Hi all,
This weekend while mowing grass with my 1958 841 diesel the engine started making some hard knocking/clunking sounds. Looking it over with my machinist neighbor, we came to the conclusion that its a broken crankshaft. By hand, I can pull the crankshaft pulley in and out of the engine about an inch!! It still starts and runs, but you can see the crankshaft pulley whipping in and out of the engine (about an inch or so) on every stroke, which corresponds to the engine noise. The bolts on the pulley are all tight so its not a loose pulley. Any ideas on how this happened or had this happen to you?? I spent big bucks on a complete rebuild on this engine a few years ago. About every moving part was replaced, except the crankshaft. I don"t know if the crank itself was magnafluxed , but probably was since it was reground. Hopefully the engine isn"t completely trashed.
Thanks

The reason it broke was because it was ground. These cranks are hardend on journals. Its broke in rod so may have to have rod bigend resized. When I worked at Ford dealer and these engines came in with bad cranks they got new ones. Can put reground one in gas engine and have no problems.

The diesels did not originally have a counterbalancer and there were lots of broken crankshafts so Ford recalled them (I believe) and replaced the crankshaft with one that had a drive gear molded into the center of it and added the counterbalancer.
An original engine without the counterbalancer that has lasted 50 years is probably not going to break. However Ford says DO NOT grind the journals so I assume you have discovered why Ford says not to grind the diesel crankshaft.
I am sure that I have a replacement crankshaft and counterbalancer if you are interested.

I have a 841 diesel engine if you need parts.

My early 841D broke its crankshaft while plowing snow. Journals had never been turned, and it only lasted 49 years.

Thanks AWHTC and Fordtractorpro for info and offering parts. Can I email you guys about parts?
I'll have to double check with the shop to confirm the crank was ground during the rebuild, but I thought they said it was at the time. I do know they had to replace the balancer during the rebuild. If the crank wasn't ground, maybe it was run long enough on a bad balancer that caused cracks? My Ford dealership found a source for new cranks out in Iowa I think he said.... for $4000!! I found others for under a $1000 new but I would assume they are all made overseas. I might be better off with a used factory one.

Thanks Shaun.

Researching a little, looks like there are forged steel cranks which I guess was the original crank in the 841, but many of the newer cranks from overseas are cast steel which can be weaker and snap more easily.

my email is open

Hello Blair , First off to clarify a couple of things 1) The Diesel cranks do not break because they were ground undersize . Ford says not to grind them because they have a Tufftride Hardened coating on them that is about .030 thick and can be turned off if done incorrectly . The coating increases the life of the crank and bearings . 2) They do however break because they were not balanced at all from the factory and they stretch and break rod bolts which will lead to breaking the crank also . 3) As Alan said Ford did recall them and change cranks and install balancer kits but did not balance the engine so it was only a partial cure to the real problem . If you remember we spoke about this before you had the engine done and the shop did not follow all of my recomendations I told you about so that this would not happen and it did . These engines are not cheap to rebuild correctly if you want them to last and it can be done but it has to be complete and correct . Do not run the engine anymore hopefully the block can be saved and the two rods may be reuseable on the journal that broke, get it out and take it apart . These early Diesels are not as tough as the later ones and if anyone or anyshop has not had any experience with them and does not know the common problems they will overlook them and this is what happens . To do it correctly you can average $5000 on the parts, machine work, and assembly of the engine only, not removing it or installing it in the tractor .

I have a used standard crank with balancer gear. Will sell as I have sold the 841 as a parts machine rather than rebuilding it.
Email is enabled.

Thanks for the info Tony, and for taking my call today to discuss. I"ll get back about what I"ll do about it.
Blair

Looks like you have lots of offers to sell you used parts. I, too, have a 172 inch diesel crank that has not been turned. Just add me to your list of possible sources.

Refrain from lugging these engines around so that you don't put extra torque against the rotating assembly, nobody wants to work your engine hard but you will get better service from these if you keep the rpm's up and drop down a gear.