115hp merc 1985 inline 6

[onbass]

Hi all,

I recently purchased a boat and am considering uprgarding the outboard. i found a pretty good deal on a used 115 merc inline6. Any opinions on this outboard other than it being a pig on gas? I Could y'all tell me about the pro's and cons? Should I even consider this outboard? Any input would be appreciated, thanks!

[Hank W]

The best inline I ever had was a 1985 Mariner 115. They are great motors but beware of the current condition. They are as expensive to have work done on them if not more than the V-6 motors. Look at the overall condition of the motor, if it is really beat up on the outside it probably wasn't cared for very well on the inside. Pull the plug/magnet on the gearcase and check for large deposits of metal on it. Check the compression. I think 130 psi is average but ask Raceman about that. Ask to see/hear it run or test ride it if you can. Peek in the cylinders with a mini flashlight. Look for any signs of water in the cylinders such as 1 or 2 really clean cylinders.Also look for signs of scoring or evidence of piston burning such as aluminum dusting on the plugs. The late model 115 s have a very good holeshot compared to the older distributor motors. I hope this helps.

[mr.clean]

i have an 86` 115 love it, for that size motor it runs like a raped ape. pushes my 16`ft baja on a good day with the right prop close to 60 mph. good luck.

[onbass]

Really appreciate your help guys.

Hank, i'm getting a good deal on the outboard, on a limited budget right now so I hope there's no surprises. I will repost regarding average compression numbers for the outboard. Speaking of compression, what would be the max variance that you would tolerate before a decision is made not to buy the outboard?

Mr clean, which prop are you running on your outboard? You have a jackplate installed? You'll be airborne if you go any faster :) I will be puttin this outboard on a similar sized boat. Heavier than yours though, it's a 16ft bassboat and will an additional person most of the time.

[mr.clean]

i have a 6in.jack plate and stock prop.if you set it up right it should run great.maybe more setback and something like a 21 chopper.

[onbass]

Thinking of installing a jackplate as well, just need to figure out my budget after taking a look at the outboard. Thanks for the quick reply! :)

[Pete Keppler]

I’m a little confused. When did Merc starting putting low dome pistons in the L6s? My 85 115 that I’m rebuilding had 135-150# in each cylinder when I bought it recently. Due to water ingestion, I’m now having it rebuilt. My rebuilder was not surprised at the compression. He seemed to believe that 85’s still had the high dome pistons.

[Hank W]

I guess I would draw the line at 120 PSI. I've always heard that within 10% is acceptable.

Pete
I thought my '85 115 Mariner had the low dome pistons...could be wrong though.