Bearing Questions

Mnethercutt · Jul 9, 2018

Posted this over on the JD forum but wanted some more feedback.

I need new conrod and main bearings. Question now, is it absolutely necessary to remove the crank and have it machined, or can I get by with just replacing the bearings? This is a parade tractor that gets on average less than 5 hours of use per month.

Also any suggestions/tips for replacing bearings appreciated.

old · Jul 9, 2018

If you can see of feel with your finger nail any thing what so ever on the crank shaft yes it need to be pulled and turned. Even better if you can mike the journals so as to be 1000% sure they are not out of round.

44 massey · Jul 9, 2018

You can get some idea if you plastic gauge it too!!! I like to even if it perfectly smooth (journals), tells me if possibly need to go oversize (.001-.002) with new bearings!!! Wont tell u if
out of round tho unless you check it then rotate it every 90% and recheck but a lot of work!!!!

Earl-IL · Jul 9, 2018

Are you having oil pressure problem ? Just a suggestion. The only way you can check main brg. clearance with plastigage in the tractor accurately, is to be able to push the crankshaft up against the upper half of the main brg. Maybe a jack and wooden blocks. Jack the center, check front & back.

Bob · Jul 9, 2018

"Get by" is sometimes a VERY expensive experiment.

Your original post reads "My connecting rod bearings all (save one) need replacing".

What are you basing this on, and WHY are you in there? Just curious? Low oil pressure? Knocking?

Unless you have the experience to judge the condition of the crank, know how to properly interpret plastigauge, and are ABSOLUTELY SURE exactly what bearings are in there now, you will be ahead to have a pro make that decision for you.

You wouldn't be asking here if you had that experience, and no one here can evaluate your crankshaft remotely, much less without so much as photos.

If you guess WRONG, you will have scrapiron when done, and it's a small tractor (simple to split and remove the crank) and a simple crank evaluation and grind (if needed) is gonna add only a hundred or two $$$$ to what you are doing, and SHOULD make for a LOT better likely outcome, IMHO.

Steve@Advance · Jul 9, 2018

A lot depends on how bad it's worn.

If it hasn't had any catastrophic failure, like a spun bearing, or run out of oil and burned, you can probably get by with new bearings. One problem though, disturbing the rear main seal may cause it to leak worse. If it has a rubber 2 piece it can be replaced without removing the crank.

Be sure to go back with the same bearing size that came out as it may have been turned before.

Ken Combs · Jul 9, 2018

I've always used a piece of business card type paper in two main bearing lower halves. Just install the cap bolts snug, no overly tightened, to pull the crank up then measure the other journal(s). Move the paper to the ones you have measured and repeat the process.

Like Old said, if you can feel any grooving/scoring etc, out it comes.

IME, mains seldom are out of round, rods often so. So mic'ing them is best.

old · Jul 9, 2018

I agree Bob. If I remember right he is also working on a tractor that parts are hard to come by and are very costly to boot. If he was the throw a rod out the side of the block due to not having things right he will then have scrap iron on his hands

37chief · Jul 9, 2018

It's possible what you want to do. You can purchase a micrometer fairly reasonable from ebay, they you aren't guessing. If the rod journals measure ok, more than likely the mains will be good also. Then just roll in a set of mains, and replace the rod bearings. Then you chance a rear main leak, but for a parade tractor you should be ok. Like someone mentioned why do anything? Stan

neverfear · Jul 9, 2018

Great reply Bob.

Mnethercutt · Jul 9, 2018

Probably should've said that I've already checked with plasti gage. All bearings right now are standard. Crank did have visible lines on it...so looks like it'll be coming out and going to a shop...

old · Jul 9, 2018

I learned decades ago if it looks iffy it is iffy and can/will cost you big time if you try to get around what may well happen if you do not jump threw all the hoops to get it 100% correct.

rustred · Jul 9, 2018

there is tools to measure a crankshaft... you just cant look at it and say its good or no good. get it measured then you know. i would not be turning a crank on an old tractor or whatever it is just because of gossip from farmers. plus what is this unit??

rustred · Jul 9, 2018

post a picture of lines. the crank can be polished and those line probably dont mean a thing. dont think this is a race engine with high rpm. these old cranks that turn 1400 rpm are pretty forgiving.

Bearing Questions

Mnethercutt

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old

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44 massey

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Earl-IL

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Bob

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Steve@Advance

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Ken Combs

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old

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37chief

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neverfear

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Mnethercutt

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old

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rustred

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rustred

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