1993 Mercury (8 HP) outboard. Propeller shaft doesn't turn

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chad101

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Just picked up an 8HP outboard off Craigslist for $200 (no prop though). The engine runs the gear shifter seems to work. However when I put in gear the lower horizontal shaft (prop connects to) doesn't spin.

The previous owner said he hit a sand bar pretty hard and the issue is most likely in the lower unit.

I just need to know where to begin with troubleshooting. Would I be better off a used lower unit off eBay?

Any help would be greatly appreciated.
 
ondarvr

ondarvr

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Re: 1993 Mercury (8 HP) outboard. Propeller shaft doesn't turn

New lower units cost far more than the motor is worth. You can either find a used LU or buy a complete parts motor, sometimes the entire motor is cheaper than just the parts.
 
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racerone

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Re: 1993 Mercury (8 HP) outboard. Propeller shaft doesn't turn

Sounds like the driveshaft snapped.------Best to remove this and find out what is damaged before spending a penny on parts !!
 
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Mi duckdown

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Re: 1993 Mercury (8 HP) outboard. Propeller shaft doesn't turn

Chad Hard to tell. drop the lower unit. BUT in forward gear, spark plugs removed, can you turn the prop. Pics would Help.
 
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chad101

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Re: 1993 Mercury (8 HP) outboard. Propeller shaft doesn't turn

Yup! The long shaft is busted right below the water pump. Found some sand (not allot) inside the water pump too.

I'm still trying to get the busted piece out of the lower unit. The bottom half of the water pump is connected to a copper tube, it's becoming a real PITA to remove this.

CAM00014.jpg

Is welding an option? If the busted piece isn't shattered...
 
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Guest

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Re: 1993 Mercury (8 HP) outboard. Propeller shaft doesn't turn

chad101 said:
Yup! The long shaft is busted right below the water pump. Found some sand (not allot) inside the water pump too.

I'm still trying to get the busted piece out of the lower unit. The bottom half of the water pump is connected to a copper tube, it's becoming a real PITA to remove this.

View attachment 229527

Is welding an option? If the busted piece isn't shattered...
Click to expand...

That copper tube is connected to the water intake seal. It should just pull out when you remove the impeller housing. Is it me or does your drive shaft look stripped?? Not to mention i do not believe your shaft is supposed to come off before top housing.
 
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chad101

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Re: 1993 Mercury (8 HP) outboard. Propeller shaft doesn't turn

The top half (metallic cover) had to be removed before I could pull the shaft. I can see the other end way down in the lower unit.

I rotated the lower housing out of the way and I see what appears to be a bearing. I take it I'll need a special tool for this?
 
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Guest

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Re: 1993 Mercury (8 HP) outboard. Propeller shaft doesn't turn

chad101 said:
The top half (metallic cover) had to be removed before I could pull the shaft. I can see the other end way down in the lower unit.

I rotated the lower housing out of the way and I see what appears to be a bearing. I take it I'll need a special tool for this?
Click to expand...

I do not know if welding is an option i am sure the more experienced member can comment on that like carholme and raceone. Please post your outboards model number. Before you spend any money. Do a compression check. If you don't know how you can youtube it
 
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racerone

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Re: 1993 Mercury (8 HP) outboard. Propeller shaft doesn't turn

Facts-----These lower units are not considered to be " robust " ---Many folks searching for used ones on KIJIJI etc etc.-------Many motors available with no lower unit too.-----------Judging by the wear on the shaft, you need to do a complete teardown and inspection.----Replace the bushings amd seals.-------Welding of precision , stainless , rotating parts is not the same as welding a bracket for a manure spreader.
 
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chad101

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UPDATE: I found a used drive shaft!!

I a small problem though.I can't the gear shifter lever back in place. Do I need to disassemble the entire lower unit?
 
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Guest

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The shift linkage needs to go on before the top plastic part of the water pump. As I look at the drive shaft again I do not see any spines that go into the gear housing to make the prop spin. Did you get a new shaft?
 
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chad101

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I got the drive shaft at a local marina/boat salvage yard for $50.

I honestly don't remember seeing any shift linkage. I think I just pulled the shifter rod out. Gosh, I wish I could remember. I have everything in a spare tackle box. Is there a diagram I could look at?

This is why I hate leaving stuff disassembeld for so long. I know better too; I should have taken some pictures for future reference.
 
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chad101

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Found the diagram (see link). I don't see any linkage for the shift rod. in the diagram it just connects to the cam, which rests inside the gear housing??
 
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Guest

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chad101 said:
Found the diagram (see link). I don't see any linkage for the shift rod. in the diagram it just connects to the cam, which rests inside the gear housing??
Click to expand...

Sorry I meant shift rod not linkage. So b #36 goes on before #18. So the shift rod goes on first and then you have to put #18 on. I had a 96 merc 6hp which I did that way. The diagram looks exactly the same
 
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