Replacing raw water engine intake hose -5/8 or 3/4

[Brian Peyton]

Hunter 340 - 2000. Yanmar 3GM30. Replacing raw water intake hose. Original hose is 5/8" wet exhaust type. Hose barb on strainer is 3/4". Barb at pump is 5/8"(could be a metric size). Good engineering huh!Should I use 3/4" hose and just clamp down tight at the pump end or replace the strainer hose barb with a 5/8" and use 5/8" hose? I am concerned I may break the little plastic strainer body attempting to remove the old hose barb fitting. Besides wouldn't the 3/4" hose provide a little better flow? I will use the high quality wet exhaust type. West Marine is $5.49 a foot.

 

[Paul Akers]

Best Flow?

Your best flow will be the diameter of the part in the flow with the smallest diameter. My boat has a 5/8" hose (ID).

 

[J. Tesoriero]

Reducer

I would use a larger hose whenever possible for a reduced rate of flow with the same volume. I have the same two hose size set-up on my boat and use a reducer fitting just before the pump. See West Marine

 

[TomH]

Brian

Brian, I have a 2000 340 also and my Intake hose is 5/8th @ pump and runs to the strainer which is also 5/8 reducer coming out of the strainer. Tou can get this to fit your strainer(probably a Sherwood or Grocco) plastic type from West Marine or Boat US. I have changed my hose and strainer already but both sides have always been the same size.