SteveH
Senior Member
- Joined
- Oct 6, 2007
- Messages
- 110
Hello
My single engine trawler is equipped with the 160 4LHA-HTP Yanmar. The engine has 540 total hours since new. The other day while cruising at 2000 RPM, (engine water temp at 170ºF) I noticed a fluctuation in oil pressure between the 4.5 and 3.5 numbers (X10 MPa) on the gauge. When I reduced the power to idle the oil pressure went to near zero, but neither the red warning light or alarm came on. When I pulled out of forward gear to neutral, the oil pressure went back up to the 2 at idle RPM of 750. When shifted back to forward gear at idle the oil pressure would then go back down to near zero. Funny thing, when placed in reverse the oil pressure would only drop a small amount. When the throttle is pushed up in either gear or in neutral the oil pressure rises to normal range of 4.5 with the intermittent fluctuations. Also, these readings are the same at both helm and flybridge instruments.
Could this be the oil pressure sending unit or something worse? Does the red oil light and alarm work on a different circuit than the gauge? A Google search did find problems with some Yanmar oil pressure sending units on other model engines. Thanks. SteveH
My single engine trawler is equipped with the 160 4LHA-HTP Yanmar. The engine has 540 total hours since new. The other day while cruising at 2000 RPM, (engine water temp at 170ºF) I noticed a fluctuation in oil pressure between the 4.5 and 3.5 numbers (X10 MPa) on the gauge. When I reduced the power to idle the oil pressure went to near zero, but neither the red warning light or alarm came on. When I pulled out of forward gear to neutral, the oil pressure went back up to the 2 at idle RPM of 750. When shifted back to forward gear at idle the oil pressure would then go back down to near zero. Funny thing, when placed in reverse the oil pressure would only drop a small amount. When the throttle is pushed up in either gear or in neutral the oil pressure rises to normal range of 4.5 with the intermittent fluctuations. Also, these readings are the same at both helm and flybridge instruments.
Could this be the oil pressure sending unit or something worse? Does the red oil light and alarm work on a different circuit than the gauge? A Google search did find problems with some Yanmar oil pressure sending units on other model engines. Thanks. SteveH