Burned up new raw water impeller

[JOHNMARDALL]

Originally Posted by Olddan1943

John, please tell us the specifics for the exhaust gas temperature sensor and alarm.... ie, make, model and price.
Thanks, Dan.

Hello Dan,

You'll find the information you need at www.borelmfg.com


All the best
John M

[Captain Bill]

I would point out that the OP's pump was working at least initially. The heat exchanger in these engines is located above the pump. There is no way that the broken blades got into the heat exchanger without water flow. If there is no water flow (like when someone forgets to open the seacock) then all of the broken and melted blades are found in the body of the pump. Please don't ask how I know. My guess is that he sucked something into the intake while underway that eventually fell out.

[Olddan1943]

Originally Posted by JOHNMARDALL

Hello Dan,

You'll find the information you need at www.borelmfg.com


All the best
John M

Thanks John

[windshadowthree]

I changed my impeller. I then immediately checked for water flow out the exhaust. No water! Seacock was open but no water in strainer basket. I filled strainer basket with water, resealed strainer top, started engine, lots of water out of exhaust. My engine is a 13 hp Yanmar. On my boat, if the strainer is not filled with water after an impeller change, there is no suction to draw the water into the system.

[Rorzech]

You didn't mention turning the sea cock open again !

[Rorzech]

Does anyone use a check valve between the through hull shut off, and the strainer, to keep it primed ?

[El Pinguino]

Originally Posted by windshadowthree

I changed my impeller. I then immediately checked for water flow out the exhaust. No water! Seacock was open but no water in strainer basket. I filled strainer basket with water, resealed strainer top, started engine, lots of water out of exhaust. My engine is a 13 hp Yanmar. On my boat, if the strainer is not filled with water after an impeller change, there is no suction to draw the water into the system.

Same same my system.

However I can run the engine for several hours quite happily and then have the pump lose prime.... happens if she takes a heavy roll to port.... cooling intake is right next to keel stub on stbd side ... it must just get a gulp of air and that - as they say - is that...

[kmacdonald]

If your pump wont self prime you have air leaks or collapsed hose, eternal or internal. The intake hose from seacock to pump should be wire reinforced to prevent collapsing.

[DotDun]

Originally Posted by kmacdonald

If your pump wont self prime you have air leaks or collapsed hose, eternal or internal. The intake hose from seacock to pump should be wire reinforced to prevent collapsing.

There is a strainer between the seacock and pump, normally above the waterline. Depending on the head caused by the siphon break, a worn pump may not prime without assistance.

[DotDun]

Originally Posted by Rorzech

You didn't mention turning the sea cock open again !

Post #2 & #3.

[kmacdonald]

Originally Posted by DotDun

There is a strainer between the seacock and pump, normally above the waterline. Depending on the head caused by the siphon break, a worn pump may not prime without assistance.

The pump would have to be extraordinarily worn not to prime. There would be no head caused by an empty siphon break or full siphon break. The bottom line is that if your water intake system won't self prime in a few seconds, there is a problem or problems with your cooling system. I suggest you repair it instead of compensating for it by manually priming this and that. Water intakes are exposed to air bubbles and even removed from the water when power boats jump wave. They don't have to stop and "prime" anything to restore water flow.

[DotDun]

Originally Posted by kmacdonald

The pump would have to be extraordinarily worn not to prime. There would be no head caused by an empty siphon break or full siphon break. The bottom line is that if your water intake system won't self prime in a few seconds, there is a problem or problems with your cooling system. I suggest you repair it instead of compensating for it by manually priming this and that. Water intakes are exposed to air bubbles and even removed from the water when power boats jump wave. They don't have to stop and "prime" anything to restore water flow.

Thanks for you suggestion!

A siphon break 3 feet above the pump is 3 feet of head.

[Olddan1943]

Originally Posted by JOHNMARDALL

Hello Dan,

You'll find the information you need at www.borelmfg.com


All the best
John M

Originally Posted by kmacdonald

If your pump wont self prime you have air leaks or collapsed hose, eternal or internal. The intake hose from seacock to pump should be wire reinforced to prevent collapsing.

IF you had a good flow before this event then, it is something you did or perhaps, the pump was ruined because of the event.
When you pull the hose off the hull valve, you get a good flow?
Consider pulling the hose of the inlet of the strainer and the hose between the strainer and the pump too.

[kmacdonald]

Originally Posted by DotDun

Thanks for you suggestion!

A siphon break 3 feet above the pump is 3 feet of head.

With a worn pump there won't be 3 feet of water in the siphon break, it would have drained out. With 3 feet of water in the uphill and downhill side of the siphon break there will be zero head. They cancel out. If you have a siphon break between the seacock and raw water pump your system is designed wrong.

[kmacdonald]

If there is a siphon break on the intake side of the raw water pump it will never prime. Siphon breaks are between the exhaust manifold and water injection elbow.