Looking for some educated thoughts. Went to change my oil this wknd on my '07 496 Mag. Dropped the Bravo drive down into my large tub filled with water. The water level was right at the cavitation plate and the intake holes were submerged. I started the engine but had no water flow thru the system. I have a closed cooling system with heat exchanger. I shut down, then re-started but still no flow and then the alarm sounded. So I figured my impeller was probably fried. Pulled the pump off, impeller looked fine and water came out. I replaced the impeller with a new one. The bronze housing is not scored other than at the very bottom of the main housing. The front cover is fine. I took the end caps off the heat exchanger and blew it all out with compressed air. Didn't see any blockage. Pulled the hoses off the exhaust elbow and didn't see anything. I then blew out the intakes on the drive. I did have a lot of nasty swamp water come out of the drive but intakes weren't plugged. The boat ran fine 2 weeks ago on my last run of the season. I had to order new gaskets for the heat exchanger so I haven't fired her back up yet but I'm baffled as to why I couldn't get any water flow??? My only thoughts are either the pump was cavitating and couldn't get a prime, or there's a blockage somewhere. Anything else I could be missing here???

It's not going to draw water up from a plastic tupperware container. You would need it to be several feet deep and to encompass the transom assembly to simulate the boat sitting in the water, making up for the water pressure around 4 feet deep. When your boat is sitting in the water, your SWP is below the water line of the boat.

Next time, either put muffs on the drive (which still suck) or install a fresh water flush Tee into the sea water side of the system right before the SWP.

So what your saying is the pump itself does not create enough vacuum to pull the water in from the Plastic Tub? It requires some pressure to force water in through the intakes to prime the pump? And just being submerged enough in the water doesn't provide that pressure? Or with a hose, that provides the pressure.

Exactly.

Makes sense so we'll go with that. Thanks, I hate not knowing what went wrong

I have used a tub to winterize my boat with a bravo drive. I used a 750 gph bilge pump connected to a set of muffs on the drive. Works great to let the motor warm up and get the antifreeze circulated.