40HP Yamaha outboard motor sitting for years

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Old 03-06-20, 03:55 PM
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40HP Yamaha outboard motor sitting for years

Hi, I have a four stroke 40HP Yamaha outboard motor on a boat that has been sitting outside for 3+ years. The motor has very low hours and it looks fine. Nothing seems to be seized up. My question is should I do anything in particular or look out or anything before trying to start the motor? Thanks
 
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03-07-20, 04:48 AM
Dixie2012
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In my limited 1st hand experience with an outboard that has been sitting up, you need to change the water pump most importantly. The water pump is kind of a plastic gear or impeller that gets brittle & dried out over time. Upon attempting to run this motor, the impeller is likely to disintegrate & get all in the motor. Obviously if you have it in water, it wont pump water either once it has disintegrated.

Chances are very good that you will also need to have the carburetors rebuilt. They usually don't hold up very well sitting over a period of years.

You also need to have the oil in the lower unit replaced/changed.

I'm sure more experienced boaters & outboard motor mechanics will correct any mistakes I have made here & add to my list.
 
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Old 03-07-20, 03:50 AM
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You can either just give it a try and see if it starts and runs or you can give it a through going through before trying. It's up to you. The big question is was the engine prepared for long term storage or was it just left to sit? Old fuel is usually the biggest cause of problems.
 
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Old 03-07-20, 04:48 AM
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In my limited 1st hand experience with an outboard that has been sitting up, you need to change the water pump most importantly. The water pump is kind of a plastic gear or impeller that gets brittle & dried out over time. Upon attempting to run this motor, the impeller is likely to disintegrate & get all in the motor. Obviously if you have it in water, it wont pump water either once it has disintegrated.

Chances are very good that you will also need to have the carburetors rebuilt. They usually don't hold up very well sitting over a period of years.

You also need to have the oil in the lower unit replaced/changed.

I'm sure more experienced boaters & outboard motor mechanics will correct any mistakes I have made here & add to my list.
 
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Old 03-07-20, 05:29 AM
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I'm with Dixie on this one.
A bad pump will destroy an engine in min. and give no warning when it's going to fail.
There's some You Tube videos on how to change some of the common ones.
It's best to change the lower unit oil after it's been warmed up so it all flows out.
You just remove the upper and lower plugs, let it run out, then fill it from the bottom until it starts coming out the top hole.
Make sure you do not run the engine at all until it has water.
 
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Old 03-07-20, 06:11 AM
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Get the numbers of the engine and with a little luck download the manual.

Remove the plugs and fog the cylinders let is sit for an hour or so.
Turn it over manually you want to make sure that the rings are free,

If you can drain the gas and check and/or replace the filter.
Change the oil.
 
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