630 JD main bearing advice

PJH

Well-known Member
I pulled the right main bearing housing, hoping to replace only the seal. Main journal looked good, and the bearing looked good, but it was finger loose in the housing. It wasn't spinning in the housing, due to the locating pin, but I don't think it should be loose. If I understand the service manual correctly, the bearing is pressed into the housing, then sized to the journal. Before pulling the housing, I had .007 inch clearance in the right main, measured with a dial indicator. I also checked the right rod bearing and journal, and they looked good. Engine oil was getting into the first reduction gear cover, and I'd hoped for an "easy" fix. I'm thinking that I might as well pull the crank and start looking for a machine shop. Am I correct in thinking that the main bearing should be a tight fit into the housing?

Thanks for any advice
Paul
 
Press fit means tight.
If the crank protrudes enough to be miked theres no need for removal.
Just measure the journal and machine the new bearing to fit.
 

.007" is ideal on that 4" Main..!!!

That replacement bearing is going to cost ya over $100.oo PLUS having it machined to you journal size.

DO NOT install any tighter than .005"

Yours may be one that just had a Main seal start leaking.. Mine had a Main Bearing clearance of .070" and made no noise and the Rod bearing showed signs of oil starvation too.(just caught it in time!)
Ron.
 
Thanks for your reply Ron. The new bearing is now around $173, if I remember right. The looseness of the old bearing in the housing bothers me. I'm wondering if a new bearing will fit tightly in my housing. I don't know how to find the OD of the new bearing without actually getting it in my hands.

My left main had .004 inch oil clearance, but the end play was 0, or at least not measurable. Should have been .005 to .010, I think. I have it ready to come off too - I want to replace that troublesome o-ring, and I'm hoping to re-use the left bearing. The left side was pretty clean for an old tractor. I expected an oily mess under the flywheel cover.

Paul
 
Thanks for the reminder Mike! I used that on a loose race in a mower gearbox, and it's held up (so far).
 

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