1977 Mercury 200 (20hp)

[caughtacase73]

I just bought a 1977 Merc Thunderbolt 20hp motor for my old boat(1977 16ft mirrocraft). This is my first boat and motor and I am looking for any advice, mostly on the motor. The only thing I know at this point is that its a 20 hp, has electric start, and is a tiller. Anything I should look out for? Anyone have history with this type motor that can give any advice?

Thanks Travis

[Sylvan75]

I had a similar engine a while back and it was good to me. Just make sure that impeller is in good shape before you trust your vacation time on it. I would start it with some water ears and check the water discharge. Replace the impeller if needed. Replacing spark plugs and lower unit oil is a good yearly maintenance idea too.

[marine_man]

Quote:

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I would start it with some water ears and check the water discharge.

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I wouldn't trust a waterpump based on this test alone, unless you crank the water pressure way down on the hose, which I wouldn't do either. When you're running the motor through the hose muffs the water pressure is forcing the water through the motor more than the water pump is forcing it through the motor. I'd back it into an access and verify it that way.

In regard to the motor, they were a pretty decent motor.. the big thing, as with any motor, is to either use the motor a lot or make sure you've got fuel stabalizer in it to avoid gumming up the carbs. That and the yearly winterization and you should be in good shape.

marine_man