1976 15hp Upper Main Bearing

Mr. Bwok

Seaman
Joined
Aug 25, 2009
Messages
58
I have a 1976 15hp Johnson and am wondering what is involved in replacing the Upper crankshaft bearing. I was replacing the upper crank seal as it was gone. I noticed the main bearing has worked its way up, it is not seated all the way down and pushed the seal onto the cam and wore the seal out, or appears like it has. I was wondering if these are pressed in and what it would take to replace it. It looks worn and I am afraid of flywheel wobble. Can you press a new bearing in, or does the block have to come apart. From appearances it looks like a new one can be pressed in. I was hoping for advice. The part number is 0386008 NEEDLE BEARING ASSY
 

oldcatamount

Lieutenant Commander
Joined
Apr 4, 2010
Messages
1,740
Re: 1976 15hp Upper Main Bearing

I believe you need to pull the crankcase away from the block. The upper, middle, and lower bearings are held in place by a short pin that enters the bearing housings from the piston side of the crankshaft cradle. How a bearing could "work it's way up" is a mystery to me. I strongly suggest that you get a service manual for your motor before you start taking anything apart. The manual will show you the steps involved, please don't just follow my advice because I'm not totally sure about your specific motor.
 

bktheking

Vice Admiral
Joined
Jul 29, 2008
Messages
5,057
Re: 1976 15hp Upper Main Bearing

There is more going on here than that top bearing, it would have no way of working itself up unless the center bearing is worn. The top bearing is held in place by just the crankcase halves, the center bearing is held in by the locating pin that oldcat is referring to , the bottom is held in by the crankcase head. I just went and looked at a block I have in the garage and verified. You're in for a complete powerhead teardown IMO.
 
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