'78 Merc 500 50hp, fix it or replace it

[hotrod53]

My boat has a '78 Merc 500 50 hp motor in need of help. It hasn't been run for 10 years but it was well winterized and free rolling. In order to get it back on the water I figure that I need to rebuild the fuel pumps, rebuild the water pump, the starter bendix needs to be replaced, and the lower case is shot therefore needing seals and a case.

Here's the question... do I fix it or replace it. I'm trying to do a budget build but I surely don't want to throw money at a piece of junk. This motor was apart a few years back when it blew a piston so it was gone over back then. I know the history since it belonged to my neighbor.

I ran across an '82 Nissan 75 hp with tilt and trim for $1000 but I'm not sure what to do with the Merc. I have been watching Ebay for a lower unit and have come close a few times but just can't find one that will definately fit.

What do you think?

 

[*EdC*]

Re: '78 Merc 500 50hp, fix it or replace it

First thing I'd do is a compression check. If all cylinders are above 100, and are within 10% of each other, I'd rebuild it. I'm certainly no expert. But, if you do the work, it shouldn't be too expensive. For what it's worth, I think, $1000 bucks for a '82 Nissan, seems a bit much.

 

[hotrod53]

Re: '78 Merc 500 50hp, fix it or replace it

I think rebuilding may be out of the question, this is a Merc 500, one of those motors where the head and block are one piece. In order to rebuild one of these, the entire crankshaft pulls out with connecting rods and pistons in tact. I am told that some of the Merc dealers won't even tough these.

 

[*EdC*]

Re: '78 Merc 500 50hp, fix it or replace it

Hot rod53'
By all means... do what is best for you....

"this is a Merc 500, one of those motors where the head and block are one piece."

There isn't a "head" on this motor. It is a water jacket cover. Here is a pic of of a similar one.