Need info on 18HP Briggs horizontal twin

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Old 06-18-08, 12:10 AM
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Need info on 18HP Briggs horizontal twin

The PTO end of the crankshaft on my recently-acquired 18HP Briggs horizontal twin can be moved about 0.020" side-to-side and 0.010" un-and-down. I can actually see it wandering around as the engine idles. That can't be good, can it?

The engine is a model 422437 type 1266 01 code 90102332.

I removed the crankcase cover to see what's going on. Here's what I found:

The ball bearing is a NSK 6307 R with one shield. The shield is on the side toward the cam drive gear.

The bearing is a fairly tight fit on the crank, but I was able to get it off by hand.

The bearing is a close slip fit in the crankcase cover, but I don't see any evidence that it's been spinning. I can easily turn the outer race in the housing by hand, though.

The bearing itself turns smoothly, but the inner race can be moved around quite a bit because of the excessive clearance.

I was surprised to see the shield on the bearing. Is it supposed to be there? The opening between the shield and the inner race is very close to the bottom of the teeth on the cam drive gear, so I guess enough oil gets squirted into the bearing.

I also expected the outer race to be a light press fit into the cover. Is it normal for it to slip around?

I'd really appreciate an informed opinion on whether I need to do something other than replace the bearing and button it back up. It's running pretty well otherwise.

Thanks,
Roger
 
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Old 06-18-08, 12:41 AM
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The in and out movement is fairly normal, but the side to side is too much, as you suspected. It sounds like the bearing is bad, and also like maybe the housing is worn a little. It may not have spun in the housing, but the walking motion of the crankshaft can kind of beat it around enough to become loose after many hours of use. Especially if the load on the pto is off balance or jerky. Install the new bearing and see what kind of fit it has. If it's close enough, use bearing locktite to hold it fast.

If it were me, I'd be inclined to remove the shield on the bearing. Most PTO bearings are open on the inside and I see no reason for it not to be.
 
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