Re: Melted a piston?
 

Sorry to hear that Gary. I always try to be optimistic. In this case, at least the thing didn't come apart. I'd concentrate on making sure that I found out exactly what caused the problem. Good luck! Lou

Re: Melted a piston?
 

Gary,


this is one thread from my Good Friday holed piston. http://www.offshoreonly.com/forums/s...gine+tech+guys

Near the end you will see the cause of just one lean cylinder.

Dont think this would apply in a blower setup, but vacuum leak seems like a possibility.

Re: Melted a piston?
 

Fortunately it's not my boat or money paying for it. Belongs to a friend, but he's not too mechanically inclined so I do most of his wrenching.
BTW, the problem was due to lack of fuel pressure. He ran it out of gas at WOT! Leaned out on the 1,2,&7 pistons, melting them. Inaccurate fuel guage, he said. Very expensive lesson for a boat he only ran 2 hrs.

Re: Melted a piston?
 

I have an adjustable low fuel pressure switch that u can get from a speed shop that deals in NOS. Normally open switch that I have set for 4.5lbs add into the Mercruiser alarm system. I also added an auto style backup beeper to the mercruiser buzzer so that I can hear it at speed. Cheap insurance.

Re: Melted a piston?
 

Good idea. I can get 5psi marine hobbs switches for about $10 and wire to the alarm.

Re: Melted a piston?
 

[QUOTE=Gary Anderson]
BTW, the problem was due to lack of fuel pressure. He ran it out of gas at WOT! QUOTE]

That was yesterday :rolleyes: I have to keep reminding myself to go back and read original post, easy to forget the facts.

Re: Melted a piston?
 

Might want to check open and close pressure on the bench, problem with the cheaper ones is that they don't consistently do what they are supposed to. The NOS switches are more expensive but very consistent with a small range between open and close pressures.

Re: Melted a piston?
 

Just found the installation sheet
Nitrous Oxide Systems
part #
15660 adj 4-7psi
15750 5psi
15680 adj 14-24 psi
15685 adj 25-50 psi

Normally open switches, about $37 jegs etc.

1/8" pipe thread

Re: Melted a piston?
 

Thanks,
I would have more confidence in that over a $10 sierra part.
Gary

Re: Melted a piston?
 

Gary, I can feel the pain
Ijust did the same thing to my newly Procharger 454Mag.
The strange this was that I didn't lose a whole lot of power.
Just pulled my piston out this AM. I burned a hole thru #5 exhaust valve, tuliped what was left, cracked exhaust seat, started burning thru the pistion and scored the bore.
I'm gonna end up lucky because I can get away with just honing the cylinder.
Just sent my carb to Dean, so that will be the majority of this lesson $$$.

Mo