1984 Merc 115 inline6

Hi Folks,

New to the board and to outboards, but I've got plenty of mechanical experience, so hopefully these motors won't throw me for too much of a ride

I just bought a 18' Sea Nymph with a merc 115 on it. I don't think the boat is rated for such a large ob, but the guy I bought it from did lots of wakeboarding with it until he had some troubles with it and never fired it back up.
Any general advice on this ob would be greatly appreciated...
- The entire ob looks like its brand new...powerhead freshly painted, wiring looks fresh outta the packaging, carbs nice and shiny...all in all an immaculate looking engine.
- He said he had it close to full throttle when heard a strange noise followed by puff of white smoke. He shut her down and never attemoted to re-start
- All the plugs look great with a small amout of fuel on them, but #1 has what looks like melted ceramic or some kind of metal on it. It's also pretty dry leading me to believe it overheated
- The motor turns over and has lower compression in #1 by about 30psi

Were these fairly reliable motors...worth a rebuild?? Anyone got 2 cents on this one?

Thanks!

Re: 1984 Merc 115 inline6

I have the exact same engine, seems like like you blew #1. I've been told they are very reliable, he probabily had his mix too lean, water in fuel, or needed a new impeller. (a long way up to #1 to get it cool) If it's as clean as you say it must have sat a lot. The best thing for the old girls is to run them, keeps everything fresh.

I believe you need a special tool to get the cylinders back in. There are a few guys on here that know their stuff. First thing they'll say us buy a manual. Good luck.

Re: 1984 Merc 115 inline6

Yup, the manual is on the way and I can't wait to get my hands on it!

Re: 1984 Merc 115 inline6

How much did you pay for the package? Running the motor is worth around $2500 + your boat. One guy on here did a rebuild and said he spend over $2000 on just parts.

Re: 1984 Merc 115 inline6

I got a 1986 sea nymph (18'), shorland'r trailer in really nice shape and the merc for $800! Good deals on boats these days...
I've seen these motors on ebay for $2500. Originally I thought I'd sell it and get something smaller but, overall, the motor's in pretty good shape so I decided to keep it and rebuild. However, I'd dump it and get something else if I'm going to have to sink too much into a rebuild.
I'm very surprised how pricey parts are for these things!

Re: 1984 Merc 115 inline6

I have never done it and i think he replaced a bunch of other things while in there. You can check on this site and see how much just a few parts would be. It might be cheaper to buy someone?s blown engine and part it out. I?ve seen someone selling just the block of an I-6 for $250 on Craig?s list. I'm sure you'll have to replace a bunch of seals and gaskets when you open her up.


I paid $800 for my 94 17" starcraft as well. He even threw in an extra lower unit and mid section w/ a trim and tilt attached. It needed a lot of work to look good though, but she runs and looks good now! You can always find good deals when someone is tired of messing w/ a problem. I did have to replace my stator though, that was expensive but much easier than your blow #1. I have 140?s psi in all 6.

Good luck with it.