John Deere 630

[mkr730]

Pulled the main bearings out of the 630. Both bearings have lost their press fit tightness but not sloppy lose at all. The right journal has a slight ridge just left and right of oil
passage, Machine shop said clearance after wear is now .011. Just wondering could these bearings last for light duty chore work. This tractor has been setting up for 15 years and
stuck. Ive broken engine lose with plans of new rings, rework head. Bore was surprisingly good. New gaskets and main seal. Any thoughts from those that have had experience with
two cylinder main bearings.

 

[PJH]

When you say "press fit tightness", are you referring to the fit between the bearing and the crankshaft or is it the fit between the outer shell of the bearing and the bearing housing? The bearings fit into the housing with a press fit, but they are not a press fit onto the crankshaft. The reason I ask - my 630 crankshaft bearings were within specifications on the crankshaft, but the right bearing was finger loose in the housing. The machinist recommended using a seal retainer (maybe Loctite brand?) and re-installing the bearings. I did everything as he recommended and it has ran good for about three years now. There is a pin in the housing that keeps the bearing shell from rotating, so I guess it was planned that they might get loose enough to spin in the housing. As far as re-using your bearings - I don't have enough experience to have an opinion. I'd like to say that it would be ideal to replace them while you are this close to them, but they are expensive, and they have to be fitted to the crank, which adds to the cost. I imagine the machinist fitting the bearings would insist on grinding the crankshaft journals. The cost just keeps getting higher.

They say that the little square section o-ring that fits between the right main bearing housing and the engine block can swell up and restrict oil flow to the right main bearing and the right hand rod journal. While you have the right main bearing housing off of the tractor, you could add a short piece of lamp tubing to keep the o-ring from swelling. The block is already threaded and the tubing will screw right in. You have to make sure the tubing is short enough that the housing will not bottom out on it and prevent proper fit-up to the block. Here's a couple of pictures of the tubing installed on my 630. This was poster Bushhog Papa's idea.

 

[mkr730]

Thanks for your reply. I was referring to bearing fit to housing. Not sloppy loose but could get bearing out without tools. The dial pin is still tight and the dial pin hole is not elongated from movement. Some folks say they never change mains in 2 cyl tractors unless they are in terrible shape.

 

[PJH]

I have an early 50 that I ran until the right main bearing was loose enough that I could lift the crankshaft by hand and feel the slop. I'm not talking about "dial indicator slop" - I'm talking about "thump slop". I overhauled it a couple of winters ago at great expense - the tractor had sentimental value.

Good luck with your project.