Buying a 1982 150 hp Mercury

Joined
Feb 4, 2014
Messages
11
The venerable old 1959 Volvo on my 19' Lund finally died (in a kind of cool way - a story for another post though) and I'm replacing it with an ob in the 115-150hp range.

I found a donor boat on Craigslist and checked it out today. Wanted some opinions (first Merc and first 'big' motor)

The motor is an 82 150hp v6 currently on 1979 fiberglass Invader. It's a clean motor cosmetically.

Compression readings: RH from top to bottom: 120, 115, 90; LH from top to bottom: 90, 90, 120. Is this a rings issue or should I be wary of cylinder wear?

The other issue was a failure to fire. Cranked well and the starter seemed strong. Spark plugs (gapless style) all had strong spark. Fuel was not getting to the cylinders so I would assume that the problems is clogged carbs (owner was unsure if it had been run dry last time it ran so probably wasn't).

So I wasn't able to hear the motor run. I told him to give me a call when he got the carbs cleaned out; so my question is should I still be interested with the compression readings the way they are?
Definitely not buying before hearing it run though
 

Dukedog

Captain
Joined
Oct 6, 2009
Messages
3,235
90's are low. Won't know till its opened up. Pistons, rings, cylinders? Any one or all three? Who knows? Could be ring tension?

First generation motor. Would need ta be "cheap" even if its runnin'.................jmo
 
Last edited:

CharlieB

Vice Admiral
Joined
Apr 10, 2007
Messages
5,617
Agree with DukeDog, if cheap enough it has possibilities.

You are looking at least into a set of rings, gaskets, and seals, at best. Depending on piston/cyl wear, a set of pistons plus the machine shop charges for boring all 6 holes.

Suggest getting the model and serial # of the motor and do your homework. Look up parts and see what it would cost you. Call a reputable machine shop that regularly handles outboard motors and get an estimate on boring all holes. Knowing your potential rebuild costs you can better gauge as to whether or not the price on this motor is worth it to you.

No matter what used motor you buy, plan on buying a new water pump kit, carb kits, fuel pump rebuild kit, all fuel hoses and primer bulb, lower unit gear oil. These all need immediate attention before you ever take any new to you motor out. You want to be sure that you minimize as many potential problems long before they ever become a problem while out on the water.

Many owners do all the above every other, or every third year, just to prevent potential problems. It's good maintenance.
 
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