1986 46 express

[daveymo]

When I exceed 1200 rpm my starboard Cat 3208 I hear or feel a grinding sound. When both motors are opened up the starboard enging is reving at 2500 rpm and the port engine is about 4000 rpm. Any info would be appreciated.

Daveymo

 

[osd9]

Assuming your motors are Turbocharged, with the motor off and keys out of the ignition, remove the air filter from the turbos and spin the turbo blades by hand. They should spin freely. Check both motors.

 

[daveymo]

Motors are turbocharged. Boat has been rarley used for past 6 years. Just purchased it this year.

 

[Boatingnut]

I gather that is a typo on the 4000 rpm on the port engine. They don't rev that high. 3100 max, in neutral. 2800 WOT, in gear.

 

[osd9]

Also, check the tachs with a laser/optical tach.....

 

[tobnpr]

What they said. Confirm no load wot rpms.
If your tach really said 4000 rpms no load it must be defective. Maybed the other one is, too.

If I'd just bought that boat- mostly sitting for the past half-dozen years, I'd have a CAT technician go through the motors thoroughly. Pay a little bit (hopefully) now- to avoid huge repair bills later.