Need help with yamaha 2013 sx240 oil pressure ?

[David Martin]

Hello
I got an sbt engine last year with 45 hrs on it. I know a real mistake. I tried to get 2 for my boat but they couldn't get me another good one last year so I built one from yamaha. But the sbt 1.8 ho all of the sudden popped a low oil pressure light . Runs 7400 rpm never misses a beat. Tested the oil pressure switch and it's good. Pulled the pump and there is some scarring on it but not gouging. Looks as if it should pump ok. Took compressed air and pulled pressure switch out and blew through engine. Reinstalled pump new oil filter and it went to 60 psi. As it warmed up it dropped to 21 on idle and 40 on full throttle. SBT IS A JOKE . I'm thinking bad tolerances on bearings. The warmer it gets the lower the oil drops. Anyone have another idea I might be missing ?

Sorry for the stupid question.............what oil pressure is the 1.8 supposed to have?? Most all pressures drop as the engine warms up 40psi is a good pressure.... JMO...... I'm not near my service manual so I'm not sure at what pressure the sensor trips at. 40psi should have good flow to all parts!! is it tripping alarm at 40psi?

 

[Brandon neidemire]

It doesn't trip at the 40. But when it's been running for a while it goes to 20. Looks like sensor trips between 18.2-23.6 psi. You know I was wondering what the running pressure of the engine is. Doesn't really say in the service manual. My yamaha mechanic said they like to see 60. Now I'm not sure if that's wot or what. Any ideas ? Maybe running 20-50 racing oil ?

 

[Brandon neidemire]

The service manual says switch operates at 18.2-23.6 I assume it kicks somewhere in that pressure range

 

[Brandon neidemire]

I been a mechanic for 25 years I know that about 10 psi per 1000 rpm is a good rule of thumb.