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2011 Optimax 250 -- on-the-water fixes

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Frank O

New member
A year and a half ago I repowered my 21' center console, moving from a 1994 Merc Offshore 3.0 L 225-hp carbureted 2-stroke to a new 2011 Optimax 250. The Optimax now has about 40 hours on it.

For a new engine like this, what are the likeliest problems I could fix on-the-water that I'd want to carry tools or parts for? I'm thinking probably fuel filter, spare fuel-water separator. I also carry a spare prop with install hardware. But I'm wondering what else you all would want to have with you.
 
It sounds like you have pretty well listed the things you could actually change on the water.

If you were going somewhere away from home/service for a few days I might add a set of sparkplugs, an impeller (and the tools to install it) and a strainer.

The "strainer" is a small (filter) that keeps crud out of the water hose that cools the compressor. I don't hear much about them anymore so maybe they have been improved it or solved earlier issues, but it used to be the source of alot of headaches. It would clog up and restrict the cooling water to the compressor, and the tell-tale (which was fed by the compressor and not the water channels in the heads).

Anyhow, the strainer, merc part number 35-8348084 goes for about 10 bucks and might be worth carrying along with your other filters...

Otherwise, unless you plan on carrying a diagnostic terminal and a box of various sensors there isn't a whole lot on these that you can fix with a wrench and a screwdriver - very complex motors...
 
Thanks. I just checked my Merc service manual for the Optimax, and it mentions the cooling water strainer that filters water flowing to the port fuel rail and air compressor. Their recommended procedure is just to remove, clean and reinstall it. But a new one can be a good idea? I guess to do either one, they say you have to remove the bottom cowl to get at the strainer.

I bought the older 2-stroke when it was 12 years old and had about 550 hours on it, and I had it for five years. When I think back to everything that went bad on it, it was a pretty mixed bag -- parts that failed that I remember replacing included the temperature sensor on the head, an oil system check valve, one of the CDMs. Also the wire for the kill switch circuit grounded out at the main harness plug at the engine, which disabled the outboard and took a while to diagnose. But I think those all were things you might expect to fail on an older engine, and aren't things I'd probably be faced with on-the-water with the new engine.

About water in the fuel ... that seems like it could be a scenario I might have to deal with eventually. The SmartCraft manual says it throws a warning if the fuel-water separator gets full. But I'm wondering if this depends on a sensor in the fuel-water separator itself? I'm pretty sure there isn't a wire running off my separator filter. If water gets past that point into the engine, is there a sensor there that will throw an alarm?
 
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Yes, on the strainer. On the earlier models it was accessible without removing the cowl - so as I originally stated they may have improved on the original design (still can't figure why they would "bury" it other than to increase service revenue).

As to the "water" alarm, I believe it's talking about the filter in the Vapor Separator filter (which has a probe/sensor in it) and not your water sep filter between the tank and the motor (if that's what you mean).

If you were unaware of the sensor in the VST, take a look at the filter in there. Should be a probe/wire coming from the bottom of the fuel filter cartridge...
 
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