Promax piston skuffing

[roadkill636]

What caused this skuffing on #5?

I had high water pressure 25#
And the buzzer went off. A month ago.
At a diffrent time.. also felt a loss of power after a long high rpm run . Felt like a cyl stopped firing.

Then last week herd piston slap. So I shut it down and tore it down.

Is this from lack of fuel?lube?
Overheat?

225 Promax
Factory staff and t stats. popet

[Merc 2.5]

Damn I hate to see that, I'll go out on a limb and say looks like heat to me

[LakeFever]

Id guess a little lean on that hole tightened the piston up juuuuuust a bit more than the others. Premix or injected motor? If the oil mix aint right that also affects combustion heat

[roadkill636]

40-1 premixed. Injectors just cleaned 10hours ago.

Probly lean to pulse pump and Vst not keeping up with the demand on a long run.

[Merc 2.5]

40-1 premixed. Injectors just cleaned 10hours ago.

Probly lean to pulse pump and Vst not keeping up with the demand on a long run.

Is it to the point of runnin out of fuel on long run ? Like start to die till u back off? I have a glass filter to watch for that sort of thang , I ve ran a few dry b4 and start to die but never had a prob like that

[gmorgan]

Get yourself a good dual readout pyrometer like a Koso and keep it under 1200 degrees. I had to get an ACU and a steam wheel.