New year...New impeller?? 7.4L Merc Mag

Last year i had the impeller replaced. Yesterday, I fired the boat up with the garden hose and let idle for 5 mins or so and it heated upto 160 before i shut it off. I noticed hardly any water coming out of the exhaust pipes and also heard a suspicious sound coming from the engine compartment. My guess is i need antoher new impeller but here's my question:

How long should you be able to run your boat on the hose w/o overheating?

Also, is there any logical reason to believe that it may be easier for the boat to circulate water when floating on the lake as opposed to running on the hose?

Thanks in advance.

tf

Re: New year...New impeller?? 7.4L Merc Mag

If you don't have good water pressure in your garden hose, two things can happen with a bravo raw water pump. One, you won't get enough water to it. And two, the pump is powerful enough to suck your garden hose flat. So if you just didn't get a lot of water to the pump, you probably didn't hurt the impeller. If you completely ran the raw water pump dry, you have ruined the impeller, at least. On my Bravo, it would take FOREVER for it to reach 160 degrees while running on the muffs. And I mean like 20-30 minutes. If I turned the pressure on the hose way down, it would warm up faster. But you should NEVER overheat you engine while running on muffs, unless you are doing something wrong.