John Deere m

[grandpa Love]

What causes this on a crankshaft bearing? Crank looks and feels smooth. The other 3 have very minor "scratches" can't feel them, or catch a finger nail on them....... Also, more on 'magic juice ' to unstick an engine, we got this motor unstuck, it was moving and probably would have run. But look at the rings. I can't imagine running it would have been good for it.

 

[randyrenfro7]

Just a little cleaning and you are ready to go.

 

[timcasbolt]

I'd bet condensation was involved.

 

[DoubleO7]

This would have been a good "reserection" thread.
All steps of the procedures to bring it back to life in one thread.
Now it is just strung out on several pages.

 

[DoubleO7]

I'd bet condensation was involved.

I bet rain got into the cylinders via the muffler and loose muffler on the manifold.
Even if the exhaust was capped.

 

[teddy52food]

Was the oil milky? Maybe antifreeze caused the bearing wear?

 

[Fixingfarmer]

Scratches just a bit of foreign material that got in you probably won’t ever find the source. The one though that you have the picture of had a good big piece of contaminate to have that sharp line and then I’m willing to bet they are exactly right had a bit of water in the oil but one other question is was it gassy? It reminds me of the condition of some of the better bearings on tractors I’ve worked on that were attempted to be resurrected out of someone’s grove and they were only relying on the rain cap for cover. But 2 cylinders were notorious for the gas doing that as well as it leaked past the carb. You were supposed to drain off the excess Oil and gas down to the top valve. On an m maybe this isn’t there but the others have it. 100 hour engine oils were a must and if it’s not going to be cared for consider heavier oil. 15w40 thinned out with gas is perfect 10w-30

 

[super99]

What causes this on a crankshaft bearing? Crank looks and feels smooth. The other 3 have very minor "scratches" can't feel them, or catch a finger nail on them....... Also, more on 'magic juice ' to unstick an engine, we got this motor unstuck, it was moving and probably would have run. But look at the rings. I can't imagine running it would have been good for it.

Ok, so what is the magic juice??

 

[super99]

What causes this on a crankshaft bearing? Crank looks and feels smooth. The other 3 have very minor "scratches" can't feel them, or catch a finger nail on them....... Also, more on 'magic juice ' to unstick an engine, we got this motor unstuck, it was moving and probably would have run. But look at the rings. I can't imagine running it would have been good for it.

I'm trying to remember the details, the guy has been dead for 20 years or so. He had a JD M or 40, don't remember for sure with a bad crankshaft. He said he cut a piece of shoe leather and soaked it in oil and used it for a rod bearing. He raised veggies and used it all year long. Said he pulled the pan and replaced the shoe leather every winter.
Old neighbor across the road from where we used to live told about being in the motor pool in the Army. They had a motor that had one rod journal tore up. The said they took a piece of clothesline rope and coated it with valve grinding compound, wrapped it around the journal and pulled the rope back and forth until they got it down so they could put a oversize bearing in it and that fixed it.

 

[rustred]

This would have been a good "reserection" thread.
All steps of the procedures to bring it back to life in one thread.
Now it is just strung out on several pages.

exactly as i thought. need to keep one project in one place.

 

[J Hamilton]

Ok, so what is the magic juice??

We all know what a certain poster would say is "magic juice"

 

[rustred]

What causes this on a crankshaft bearing? Crank looks and feels smooth. The other 3 have very minor "scratches" can't feel them, or catch a finger nail on them....... Also, more on 'magic juice ' to unstick an engine, we got this motor unstuck, it was moving and probably would have run. But look at the rings. I can't imagine running it would have been good for it.

lack of oil changes, foreign material getting pumped around. oil pressure, wear and tear. and oil grade. and the rings are done once stuck and worn. now you see first hand what i was pointing out on the cub that was assembled with used parts. hands on is the best experience. so i will point out again to keep all your work in steps and in one place for future learners. it will be a from start to finish project. and thats nice to see whole completed projects. and thats why i was asking for your brg. clearance on the used ones, cause if your at max clearance they are done also. to put it this way i would only reuse them if it was the last set in existance and i had to get the tractor running on a friday night to go into town for a wagon load of beverages for the weekend party and this was my only transportation.

 

[grandpa Love]

Ok, so what is the magic juice??

ATF (transmission fluid) and acetone..... Which , when mixed together separates almost immediately........ . I firmly believe Free-All or Deep Creep is a better choice if you believe in magic

 

[Geo-TH,In]

I bet rain got into the cylinders via the muffler and loose muffler on the manifold.
Even if the exhaust was capped.

007
I'm convinced rain is public enemy #1 when it comes to damaging lawnmowers and tractors.
I know of two lawn mowers that were ruined because owners left them outside.
The carb fills with water, water runs into the engine, everything turns to rust. Mower deck bearing rusted solid.
About 15 years ago I bought a Jubilee. I changed the fluids and water ran out of the transmission.
All my tractors stay under a roof. In 2019 I finally bought a tractor with a cab and I built a second pole barn for it.
I'm guessing Gp could write a book about rain damaged Cubs.

 

[KLPinNC]

Check the head for a crack. I have seen several with a crack.