Oil Pressure

[luckyj]

Went to Lake Billy. New boat to me. 1989 Striper I/O. 3.0 OMC. Cobra Stern Drive. Noticed that after running at about 3500 rpm for 40 minutes the oil pressure dropped to about 0. But was fine the next day about 30. Any suggestions? Maybe viscosity? Oil pump?

[fishkisser]

First of all you need to check the pressure with a good automotive pressure gauge, don't rely on the boats gauge...
Make sure the oil is of the right viscosity for the operating area you are in. Many times boaters will run the same oil as in their cars, which is too thin.
Make sure the oil is between the full and low marks on the dipstick. DO NOT overfill...
At 2,000 RPM you need at least 30# of oil pressure. Which you have. So it seems only at idle are you having suspicions of low oil pressure ???
Did you change brands or viscosity of oil???
In high mileage motors and with todays oils when the motor warms up and the oil thins it is perfectly normal for the oil pressure to drop a great deal. You should be showing at least 4# at idle. However if there is no noise from the motor, no clacking of top end parts, then the motor is getting enough lubricant.
Hotter the weather the higher the viscosity oil you should use and fixed viscosity at that ...
Hope this helps ... Barney :wave:

[luckyj]

First of all you need to check the pressure with a good automotive pressure gauge, don't rely on the boats gauge...
Make sure the oil is of the right viscosity for the operating area you are in. Many times boaters will run the same oil as in their cars, which is too thin.
Make sure the oil is between the full and low marks on the dipstick. DO NOT overfill...
At 2,000 RPM you need at least 30# of oil pressure. Which you have. So it seems only at idle are you having suspicions of low oil pressure ???
Did you change brands or viscosity of oil???
In high mileage motors and with todays oils when the motor warms up and the oil thins it is perfectly normal for the oil pressure to drop a great deal. You should be showing at least 4# at idle. However if there is no noise from the motor, no clacking of top end parts, then the motor is getting enough lubricant.
Hotter the weather the higher the viscosity oil you should use and fixed viscosity at that ...
Hope this helps ... Barney :wave:

Thanks for the info Barney. Much appreciated.

[Pilar]

Sounds like a hot motor to me. Make sure your water pump is working right. If you changed nothing else then this is the most likely thing.