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2005 mercury optimax 115 saltwater

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gizmolvr

Contributing Member
Have the opportunity to pick o

Have the opportunity to pick one of these up for $2500 with 100 hours on it. Is this a good price? What should the compression be and what else should i check when inspecting? Thanks for the help
 
"John fairly new motor and old

"John fairly new motor and old enough in the Opti line that they worked the initial bugs out.

That in itself makes me a little leary of the price, I would expect a 3 year old 150 Opti to sell easily for 4-5K if not more since a new one is selling for over 10 grand.

I would not test this motor out myself, but would insist that the deal not finalize until after you have taken to a Merc certified tech and had it checked - may cost you 100 bucks to have it hooked up to the computer and read, but could save you a few grand in a rebuild.....

Maybe you are just onto a good deal - they are an outstanding motor, but the price just seems a little too good to be true for a 3 year old motor..."
 
Thanks for the reply. The curr

Thanks for the reply. The current owner just got 2 verados at cost that is why he is selling. He states that he did have them checked by a merc tech and there were no issues and they had 105 hrs. I do plan on having them checked by my own tech before finalizing but want to check compression on them first before investing any money/time. What should comp be on them when cold?
Another issue:
The boat i will be putting the merc on used to have a pre mix engine(mixed gas in onboard gas tank)and i have 40 gallons of premixed gas in it. What do you suggest i do when i install the optimax(mixes the oil itself and uses higher grade)?
 
"John, Merc pegs the compressi

"John, Merc pegs the compression on these between 110 and 130 with no more than 15 psi difference between cylinders.

As to your 40 gallons of "mixed" gas - you don't want to run that into an Opti.

The Opti's have two different injector systems. "normal" fuel injectors feed the fuel rails. They can tolerate the mixed gas, but the direct injectors that feed the cylinders from the fuel rails do not like mixed gas at all and you could well cause them to clog.

The Opti's use very little oil to start off with. At idle they are running at 300 or 400:1 and even at wide open throttle the ratio would be about 60:1 (or even less).

By design the oil is mixed with air and moves from the lower crankcase into the cylinders, then at near full compression the gas is "direct injected" into the cylinder, so the only time the gas and oil mix is right in the cylinder.

I would suggest you find another use for the mixed gas and get it out of the tank before you strap an Opti on.

One other note - find yourself a good supply of spark plugs. Merc will never tell you this outright but the Opti's absolutely devour spark plugs - they are usually toast after 50 hours of run time, and they retail for near 15 bucks a piece. Find a good wholesaler and buy them by the mini case (12 plugs)....

I'm not trying to discourage you from the motors - they are outstanding and all in all even if you run them 100 hours a year 200 bucks in plugs per engine is still a small amount compared to the 11K retail price of the motor, but just something to be aware of "ahead of time" - if you try running old plugs the motors run like garbage if they even start at all..."
 
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