Metalic Noise from outdrive/engine

[jrisebo]

When I try to go on plane, I hear a nasty metallic-rattiling noise at about 2000 rpm. Is almost like someone hitting a piece of sheet metal. In neutral I can goto 3000 rpm, no noise, so I am thinking out drive. Anyone have any specific idea what to look at?

2000 5.7 GS, Duo-prop outdrives.
Thanks

 

[skydiveD30571]

Re: Metalic Noise from outdrive/engine

First thing's first, check the outdrive oil level, then drain and check it for metal flakes. The drain plugs have magnets on them so check those carefully as well.

 

[jrisebo]

Re: Metalic Noise from outdrive/engine

Thanks, we will have to have the boat pulled for that, (33' cruiser) so I am gonna have the outdrives serviced, bearing checked/ aligned, etc.

 

[Bondo]

Re: Metalic Noise from outdrive/engine

When I try to go on plane, I hear a nasty metallic-rattiling noise at about 2000 rpm. Is almost like someone hitting a piece of sheet metal. In neutral I can goto 3000 rpm, no noise, so I am thinking out drive. Anyone have any specific idea what to look at?

2000 5.7 GS, Duo-prop outdrives.
Thanks

Ayuh,.... Check the contents of the fuel filters for Water,...

If it's goin' Lean, that's Detonation yer hearin',....

 

[jrisebo]

Re: Metalic Noise from outdrive/engine

We thought about detonation or pre igintion knock, but why so smooth at 3000 rpm when no load? Why does it start so easy and smooth?

 

[ericv26]

Re: Metalic Noise from outdrive/engine

It takes a load on engine t hear detonation. I had same issue last year with mine. found all plug tips burnt

 

[Bondo]

Re: Metalic Noise from outdrive/engine

It takes a load on engine t hear detonation. I had same issue last year with mine. found all plug tips burnt

Ayuh,.... Exactly,....

Revin' the motor to the moon,.... does nothin', shows nothin', 'n is of Zero diagnostic help,....

Load, on a Lean runnin' motor is the most common cause,...
outa time, can promote Detonation too,...

 

[jrisebo]

Re: Metalic Noise from outdrive/engine

ok, so I should be checking for water and the plugs? So timing can be an issue too?

 

[jrisebo]

Re: Metalic Noise from outdrive/engine

Had a mechanic look at this, and he says its not the outdrive, or a fuel issue. He wants to do a compression test of each cylinder, and see what that results in. Not a normal test, but something where you bring each cylinder to TDC, and then pressurize.

We will see.
Thanks

 

[jrisebo]

UPDATE: We have determined that its coming from Cylinder #3, either a wrist pin at the piston or something in the lower end. Either way, its a pull out and rebuild or replace. Also someone said it could be the skirt of the piston broken. Engine runs, no noise without load, but at about 2100 rpm, its metal on metal clank