High Engine RPM to Prime Raw Water Pump

[mnewman949]

I have had an issue since I purchased my boat where it take a good amount of engine RPM (2500) to Prime Raw water pump. When I first get the boat in the water I let it idle up to temp around 160 - 180 degrees. At this time I need to run the RPM's up to get raw water circulating around my Heat Exchanger.

While I can live with this little procedure I would like the system to function as intended.

More Info:
1997 Volvo Penta 4.3
DP-SM Outdrive
New Exhaust Risers and Manifolds
No Thermostat at this time
New Raw Water Impeller
No Leaks inboard in cooling system.

 

[Don S]

Re: High Engine RPM to Prime Raw Water Pump

Shouldn't take that long or that rpm to prime the pump in the water. Sounds like an air leak somewhere. Have a look at item one in the link below.
VP.?/ 357328

 

[GilligansIsland]

Re: High Engine RPM to Prime Raw Water Pump

Are you saying it has to run UP TO temperature, before you bring it to that RPM at which time it primes the pump?

I think you certainly have a leak, but I think you're also killing your impeller and making it worse. The thing I would do next, is pull the impeller and see if it's still intact. But that's JMHO.

 

[jeffnick]

Re: High Engine RPM to Prime Raw Water Pump

Had the same problem on the muffs with my 260A - it's raw water cooled. Had to get the temp way up to get water out of the exhaust. Once it started, it was fine. After checking everything and finding nothing, the next time I ran her on the hose, when the temp got up over 150 with no exhaust water, I pulled the intake hose off the pump and there was no water in it. I pulled the impeller and found it in good shape, but it had a set to it. I replaced the impeller and things are now fine, just seconds to exhaust water.