Which motor to rebuild

[keithhlars]

I have a fairly large patio boat that is rated up to a 90HP motor. The is currently a 1991 70HP 3cyl Johnson that was run without a straight gas mix and has lost 50% of its compression.<br /><br />I also have an 82 Merc 115hp inline 6cyl with good compression but that last time it ran was over 10 years ago. At that time we hit a rock skiing so the prop shaft is no longer straight.<br /><br />How concerned should I be about using the 115 when the rating is 90 max?<br /><br />And what is the likely-hood that the lower unit can be fixed or does it make sense to just buy a rebuilt one? The mechanic I spoke with said the Merc is too old to deal with because you don't know what else might be wrong since it hasn't run is such a long time. <br /><br />Or should I just have the newer 70HP Johnson rebuilt?

 

[JB]

Re: Which motor to rebuild

Hi, Kieth.<br /><br />Rebuild the Johnny, sell the Merc for parts.<br /><br />Good luck.

 

[alcan]

Re: Which motor to rebuild

Hi Keith<br />I would repair both of them.

 

[Valv]

Re: Which motor to rebuild

Rebuild the Merc, sell the Johnny (just to start an argument.... ...just kidding).<br /><br />There is a guy looking for a block for a 115hp Mercury, you might want to make a deal with him and sel for how much will be your rebuild.<br /><br />You should stay with the recommended max rating, even though your boat will handle bigger (but not too big) motor. It's just a matter of Coast Guard sticker and possibly insurance refuse to pay in case of accident.<br /><br />I still don't understand ratings myself, there are 16' bass boats with 225hp, and some bigger 19'/20' fiberglass at 140hp max....go figure

 

[keithhlars]

Re: Which motor to rebuild

Valv,<br /><br />How do I find this guy. I search on 115 Merc and found a guy who has a 115 with a bad PH, but is looking to buy a 90HP 4 stroke. Is this who you are talking about or someone else.<br /><br />Keith

 

[Valv]

Re: Which motor to rebuild

Keith, it's just few posts below you.<br /><br /> http://www.iboats.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=17;t=011462 <br /><br />val

 

[FlyBoyMark]

Re: Which motor to rebuild

Something to consider, if the old Merc wakes up and runs ok....its power head rated and being a little worn and derating for the prop it might only equal a 100 hp current engine, so its rite in the envelope for your max power requirements. I would look at the overall condiition of BOTH engines and select the best then 2nd., repair cost.

 

[ehenry]

Re: Which motor to rebuild

If all thats wrong with the Merc is a bent prop shaft I'd go with it. The shaft can be straightened. I just had it done on my engine for a fraction of the cost of installing a new shaft. Your problem is going to be putting a 115 horse engine on a boat rated for a 90.