Raw Mercruiser Sea pump bad

[tbalt]

HI,<br /><br />I'm not used to this type of cooling system so any info would be great. I have a 1990 454 Mercruiser with a bravo 1 drive. The drive itself doesn't have a raw water impeller inside, instead it has a sea pump that is belt driven by the motor. Today I hooked muffs onto the drive as I used to do with my alpha and the sea pump shredded the rubber impeller. My question is can I use muffs with this setup or not? I dont see how the sea pump can get water with muffs on the lower unit. If that was the wrong way to do it how can I do it.<br />Thanks

 

[Don S]

Re: Raw Mercruiser Sea pump bad

You may have a thru hull pickup instead of coming from the drive. Follow the intake hose from the pump to where the water comes from.

 

[tbalt]

Re: Raw Mercruiser Sea pump bad

I checked it out and the sea pump is hooked to a hose that connects to the lower unit. Does that mean there is a second impeller in the lower unit?<br />If so why would there be two impellers to feed a single motor?<br /><br />Thanks

 

[Don S]

Re: Raw Mercruiser Sea pump bad

Bravo drives do not have raw water pumps in the drive. The impeller may have been bad, or your water pressure low, air leaks in fittings, or a hose or fitting is blocked with something, kinked hose somewhere, or ????<br />You are just going to have to check it out. New impeller check the system for everything.

 

[Fishermark]

Re: Raw Mercruiser Sea pump bad

I've read in various manuals, etc that you need to be careful not to put too much water pressure when running on muffs. I learned the hard way that not enough pressure is just as bad - if not worse. <br /><br />I don't know if that is/was your problem or not, but don't be afraid to turn the hose full on. Any excess water will just go out the sides of the muffs. When you think about it, it is a long way up to the raw water pump from the bottom of the outdrive.