1990 Mercury 8hp - Is this play normal with the prop ?

Putzaroni1

Petty Officer 2nd Class
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Oct 20, 2012
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108
I am not sure if this is normal but I took the prop off to flush the motor and noticed it when I put it back together.
I'm not sure if I did something wrong or if this is the way it's supposed to be. If anyone can shed some light, I'd appreciate it.

https://www.youtube.com/watch?v=xlu5ym8_BBk
 

flyingscott

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Apr 8, 2014
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7,985
Do you have the thrust washer that goes behind the prop on? Or is the propshaft moving?
 
Last edited:

Putzaroni1

Petty Officer 2nd Class
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Oct 20, 2012
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108
I believe it's on there. It is like a key into the Lowe unit then the prop, the. Another washer then the nut. The drive shaft does not move.
 

Texasmark

Supreme Mariner
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Dec 20, 2005
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14,544
Play results in long term damage and as a result usually prevented. In larger engines (for sure) the prop shaft does move slightly back and forth and that's in the gearing inside the LU and is due to an overrun clutch therein for deceleration. On the 8 it may have been omitted due to the low hp. Prop slop on the shaft is a no no. Example, on a 90 hp engine and lots in that hp range the torque on the prop nut is 55 ft-lbs which translates to the prop hard locked to the shaft. I do recall that back in the days of the drive pin (primarily OMC engines) with the hole in the shaft where the pin went through the prop and the shaft to lock them together (like splines do now), there was a little slack, but very little.

HTH.
 

Putzaroni1

Petty Officer 2nd Class
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Oct 20, 2012
Messages
108
Thanks but this seems more like something's missing or assembled incorrectly. I didn't notice the play until I assembled it after taking it apart to flush the motor but when I look at the schematic on Marineengine.com everything looks to be on there.
If the prop shaft doesn't move then what is worn?
 

Texasmark

Supreme Mariner
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Dec 20, 2005
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14,544
Take pictures:

1. Side view of prop shaft without prop.
2. Diagonal view of thrust washer and then install it after the picture.
3. Slide the prop onto the shaft and push it against the thrust washer. Take a side view of that.
4. Put the locking washer on and the prop nut and tighten it. Take a side view of that.

Post the pictures and let's have a look.
 
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