Raw water issues

[Pack Mule]

This past weekend I chased air leaks on my raw water side . One was its the top of the raw water strainer and the other at the raw water pump . I finally got it running a consistent 180 degree temp for over two hours at 1700 rpm and no air bubbles in the strainer . I still think I can get better flow out the exhaust. The impeller is new. The pump is an orberdorfer . Today I ordered new a new cam , cover plate , o ring and screws for the pump . I was going to get a new raw water strainer but couldn’t justify the bucks . I added a new o ring to the top of the strainer. I think I could probably just resurface the cap and get a better seal.
Just about everything that I’ve had to work on that is mechanical on my boat has had tell-tale signs of the PO having issues , anybody else notice this kind of thing with their boats? This is not my first time with this air issue . I’m going to do my best to end it this time .

 

[Lou_tribal]

This past weekend I chased air leaks on my raw water side . One was its the top of the raw water strainer and the other at the raw water pump . I finally got it running a consistent 180 degree temp for over two hours at 1700 rpm and no air bubbles in the strainer . I still think I can get better flow out the exhaust. The impeller is new. The pump is an orberdorfer . Today I ordered new a new cam , cover plate , o ring and screws for the pump . I was going to get a new raw water strainer but couldn’t justify the bucks . I added a new o ring to the top of the strainer. I think I could probably just resurface the cap and get a better seal.
Just about everything that I’ve had to work on that is mechanical on my boat has had tell-tale signs of the PO having issues , anybody else notice this kind of thing with their boats? This is not my first time with this air issue . I’m going to do my best to end it this time .

If you see no air in your strainer and pump working normally what make you think you can have better water flow in your exhaust?
When my engine is running at cruise speed (1800rpm) I get around 165F-170F in a raw water at 70 to 75F so I would not worry about 180F if you are in warmer water.

L

 

[Pack Mule]

If you see no air in your strainer and pump working normally what make you think you can have better water flow in your exhaust?
When my engine is running at cruise speed (1800rpm) I get around 165F-170F in a raw water at 70 to 75F so I would not worry about 180F if you are in warmer water.

L

I’ve seen and heard better flow. Joy is constantly checking water flow while we’re cruising and lately since my hearing is getting worse she has been bringing more sounds to my attention. I’m not getting the swoosh out the exhaust I’ve heard before . It may not help the temps any but this has been a nagging issue for the last two summers and I just like the PO have been putting a band-aid on a bullet hole . I think I can do better .

 

[O C Diver]

Have you checked the heat exchanger and the transmission cooler for good water flow. Might be some impeller bits blocking some tubes. Might also be worth checking the exhaust mixing elbow for good flow.

Ted

 

[FF]

Simply disconnect the discharge hose for 10 seconds while underway at cruise RPM , and see the volume and pressure..


Could just be a rust blockage in the exhaust riser.


Your wash down pump could be a substitute while trouble shooting , if its large capacity.

 

[JohnEasley]

Have you checked the heat exchanger and the transmission cooler for good water flow. Might be some impeller bits blocking some tubes. Might also be worth checking the exhaust mixing elbow for good flow.

Could just be a rust blockage in the exhaust riser

That's where I would look next, too. Very common issue.

 

[Pack Mule]

Thanks guys . I will check it all out .

 

[Lepke]

If you're drawing air into the raw water you could have a blockage on the suction side or the intake plumbing is too restricted or too small. Too many sharp bends, thru hull undersized, long suction run all can cause high suction vacuum.

 

[Pack Mule]

I’m pretty sure I’ve got it fixed now . To start with my fan belt was a little loose , that helped with my fresh water flow side. I also had a slight kink in my hose off of the heat exchanger to the exhaust elbow.I also cleaned up the seal at the top of strainer . I ran it for at least two hours at 1800 rpm . Temperature held constant at around 175 , the best in the last three weekends. I still have parts coming for my raw water pump . May just hang on to them till I need for sure .