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Merc 30 - bad buy - low compression - what to do.

Maple

New member
Last spring, in a rush to buy a fishing rig, I purchased a used boat/motor/trailer combo, including a 2-stroke 1982 Merc 30, which was advertised as being "mint". As it turns out, the bottom cylinder has no compression. It runs fair except at thigh speed when it misses badly.

I'm in a quandry what to do. Should I have it professionally fixed for $1500? Sell it for parts for $300? Attempt to fix it myself?

I have no great experience in engine work but am willing to try it over the winter, if there are chances of a good outcome, and depending on what the parts might cost.

Any suggestions would be appreciated.
 
The serial # is 6141707. I'm led to believe by a dealer that it's a 1982 40 hp choked down to a 30.

Thanks for the interest.

I do have a short video of it's performance but will have to find out how to post it here.

Yes. I had a mobile outboard mechanic come and diagnosis it multiple times, and we; changed all the hoses, filters and hose/tank gaskets, changed all the fuel and oils, and rebuilt the carb. Only then did we check the compression, and the lower cylinder pressure was pretty much non-existant.
 
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Your motor is a 40 hp 1982 sounds about right. My 2 cents you are better off selling for parts and spend $1500 on a much better and newer motor.
 
You could spend 1500 bucks on it and have a motor worth $800 or $900 once it's up and running.

rule 1 - "mint" is a weed that is used to make jelly for lamb chops and give menthol cigarettes their flavour

rule 2 - motors that are "perfect" are never for sale

rule 3 - if in doubt have it checked out - after applying rule 1 and 2.
 
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