115 optimax troubles

[Kmorningstar01]

ive got an 05 115 3 cyl. Opti. Got motor with 2 low holes. Rebuilt motor with new pistons and gaskets. Fired up on stand and sounded great... Against better judgment i hung it on my boat... knowing I shoulda shipped out Injectors for cleaning and checking. Motor lasted 7 mins on the water and burnt another piston. #3 again. Pull it down replace again. Shipped out Injectors. #2 air injector comes back NFG. Now this is where I’m lost. Would a #2 air injector cause #3 to get no air because it was suck open causing #3 to run lean?? Please help, I can’t keep sticking pistons in this thing lol

[Kmorningstar01]

Anyone an opti guru??

[Kmorningstar01]

Motor serial is 1B026973

[EuropeanAM]

First- Air injectors mix air for the purpose of ATOMIZING the fuel as it's delivered. They don't really deliver the "combustion air" (that's drawn through the intake and throttle plate as with any traditional 2-stroke).

Injector problems in Optimax Engines CAN affect nearby (or other) cylinders. Direct/Air injector failures tend to CASCADE (meaning that one weak or intermittent injector may result in failure of MULTIPLE injectors within a relatively short amount of runtime).

Don't know who you used for the injectors... but if they are telling you it's bad, it very likely is.

[Kmorningstar01]

Yeah I get that it’s bad but I’m scratching my head how a #2 failed his test but yet #3 piston was melted

[EuropeanAM]

Wonder if it's possible #2 and #3 got swapped around somewhere between the engine and his equipment?

[Kmorningstar01]

I had them marked and labled. As did he when they returned.

[billnorman1]

Is the timing adjustable on this engine?
Was it resleeved or honed?

[EuropeanAM]

Timing is PCM controlled.

[SilverFox579]

Where were your injectors "shipped out" to?

[Kmorningstar01]

Spectrum marine in ft Myers. I think was the name. He’s a friend of a friend. Let’s not start the finger pointing game. I trust him and his work. Block was able to be honed.

[SilverFox579]

Not about finger pointing it's about finding someone who can properly test Optimax injectors under the same conditions when in your engine. Might take a few minutes and visit this page to read more about testing, cleaning, and validating Optimax injectors - http://europeanmarine.org/injectorservice.html

[EuropeanAM]

In regards to your questions about #2 vs. #3, we also have to remember that the engine shares a common exhaust area, meaning that debris from one cylinder CAN migrate to another in some circumstances.

It is also possible for passage of small debris through the DI, across the rail passage, and into another DI.

If you trust this shop's abilities... follow the recommendations made.

[Kmorningstar01]

I’m going to get a gauge to check the air and fuel pressures. I’ll report back with my findings

[Kmorningstar01]

In regards to your questions about #2 vs. #3, we also have to remember that the engine shares a common exhaust area, meaning that debris from one cylinder CAN migrate to another in some circumstances.

It is also possible for passage of small debris through the DI, across the rail passage, and into another DI.

If you trust this shop's abilities... follow the recommendations made.

so I’m looking at the sheets the company gave me. They say before cleaning they flowed 25ML at 20sec at 6000rpm. After they cleaned them the results went to 36ML at 20sec at 6000rpm. That’s almost 40% of fuel missing when i had a melt down. Would that cause my issues ??

[Kmorningstar01]

Air and fuel pressures with dead on what the manual calls for

[EuropeanAM]

so I’m looking at the sheets the company gave me. They say before cleaning they flowed 25ML at 20sec at 6000rpm. After they cleaned them the results went to 36ML at 20sec at 6000rpm. That’s almost 40% of fuel missing when i had a melt down. Would that cause my issues ??

Were these the Fuel or Air Injectors?

Really can't tell much from single-line info (have to look at the whole picture).

[Kmorningstar01]

Sorry this was fuel injectors

[EuropeanAM]

so I’m looking at the sheets the company gave me. They say before cleaning they flowed 25ML at 20sec at 6000rpm. After they cleaned them the results went to 36ML at 20sec at 6000rpm. That’s almost 40% of fuel missing when i had a melt down. Would that cause my issues ??

Knowing now that these are the Fuel Injectors, It would be very unlikely to see this type of overall increase in flow unless the injectors were ALL severely restricted (such as is seen with an engine that sits for an inordinate period of time).

Can't tell much from those numbers, but it wouldn't surprise me in the slightest if these are now way RICH (high flow), which can actually result in a number of performance problems.

[lpugh]

Yeah I get that it’s bad but I’m scratching my head how a #2 failed his test but yet #3 piston was melted

I can see very well how that could happen with a air injector stuck open, during the combustion process a lot of pressure is developed that would feed back into the air rails thru the open direct injector, spiking air pressure enough to reduce fuel/air pressure spread thus reducing fuel flow from another injector at the moment of the increased air pressure, I doubt the tracker valve and pressure regulators would be able to compensate for that completely. A pressure wave from the combustion process is pretty intense, think of 2 cycle expansion chambers and how they function, pressures and timing of the pulses
Just theory on this is, not a fact
Any thoughts on that Merc guys ?