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Crankshaft play problem/question...

T

Tygo

New member
Hello,
The crankshaft of my outboard motor has play when I turn the flywheel.
When one of the pistons is at TDC the play is bigger, then when turned 90° further.
I am wondering if this play is normal?(listen to video)
Does it have to do with temperature tolerance?


I've rebuild two stroke motorcycles before and I was tough that there cannot be any play.
It is a Johnson 9.9 (1977, code: 10BA77)
Any help would be much appreciated!
Tygo


 
Last edited:
Are you speaking of vertical play... abnormal up/down play of the piston at TDC... OR... that the piston has NO vertical play which is normal... and what you're concerned about is that the piston does not move and just sits there while the flywheel continues thru with its sideways throw?

If there's no vertical play at any position, there's nothing to be concerned about. That momentary freeze of the piston at TDC as the crankshaft moves on is just the nature of the beast.
 
I watched the video. You are rotating it with your fingers. But is this with pistons at TDC or mid-stroke? Normal if at TDC. Mid stroke ???. Depends. Roller bearings cannot be set up with zero clearance, so maybe you are just feeling the normal clearance. How does it run and sound? My knee-jerk opinion is it is fine.
 
Thanks for the quick replies!
I've made another video exactly explaining the problem. (Or my way of thinking)
It's the play of rotating the flywheel. Which infernally is connected to the connecting rod,
I am scared that the play is in the connecting rod bearing.
But can this be the tolerance for when it is hot? Or is this way more serious...

Oh, I'm Dutch, please accept my accent:)
Thanks again for any help!

 
Yes, we understand. Please re-read our comments. The bearings are roller bearings, not affected by normal temperatures.
 
That is al normal I think.-----When one piston is at the top the other is at the bottom.-----Normal behaviour for the bearings in this motor.
 
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