Mercury 115 I6 rebuld questions

[gregpro50]

I have an '86 Mariner 115 powerhead that I would like to rebuild myself possibly. The motor seems to run well but compression varies from about 120 to about 140. It also seems to have a tick at idle. The motor looks like it has been opened up before (new gaskets). I'd like to go through it to freshen it up. Is this something that I can have the local machine shop check out, hone, bore if necessary and reassemble myself? I've rebuilt car engines myself before and I am not scared to tear into things. I've also seen that Clams Canino specializes in these and I was thinking I could just turn it over to him too. I'm impressed with his knowledge and feedback about his work. I'm pretty anal about the way things are done and I want them done right. I'm just not sure what the best option would be. Talk me into something either way.

 

[Chris1956]

Re: Mercury 115 I6 rebuld questions

Greg, If your compression is 140-120PSI, a rebuild will not get you much more, if anything. If the motor seems tired, it is either not tuned properly, or your expectations are too high.

 

[gregpro50]

Re: Mercury 115 I6 rebuld questions

The individual compression numbers dont bother me. Its the range. I've also never had the motor on the water. It's just been run on a stand. The condition of the powerhead aside, I was just inquiring how feasible it is for me to attempt a rebuild or if I should just have someone do it for me.

 

[Chris1956]

Re: Mercury 115 I6 rebuld questions

The compression variance is not great eough to bother with, IMHO. I would fix that "tick-tick-tick", since that could be a problem looking for a place to happen.

As for doing the work yourself, if you rebuild it, it makes sense for you to do as much of the work as possible. Boring a cyinder is $50/hole or so, new oversize piston sets are $100 each, new gaskets $75 or so. it will not take too long to get out of control on the cost for a motor that is worth $300-500.

 

[CharlieB]

Re: Mercury 115 I6 rebuld questions

The Stacked 6's are a part of boating history, classic, as well as being strong running motors.

If anyone interest is purely blue book value, there wouldn't be any left.

Only you can decide the personal value of your motor, whether to save it and continue to own and operate your classic, or sell it to someone else that will.

 

[gregpro50]

Re: Mercury 115 I6 rebuld questions

Thanks guys, that is some of the info I am looking for.

I dont care about the "market" value of the motors. I have half a dozen of the old inlines in my garage that I play with as a hobby. I've done everything except actually rebuild one yet.

 

[achris]

Re: Mercury 115 I6 rebuld questions

Thanks guys, that is some of the info I am looking for.

I dont care about the "market" value of the motors. I have half a dozen of the old inlines in my garage that I play with as a hobby. I've done everything except actually rebuild one yet.

My favorite engines... I love them at 5,000rpm .. Not difficult to rebuild... Just follow the Merc service manual to the letter... The only tricky part is the exhaust water pocket cover plate... It must be done properly, or they'll leak water into the cylinders....

And to get them to run really sweet, get the carbs synched up EXACTLY.... and don't over time or over prop them....

Chris............