Raw water pump is not turning on mercruiser magnum inboard

[Chaz7R]

Started the boat today to a awful belt squeal. Opened the shroud and saw that the pulley on the raw water pump was not turning (took the blet off and was barely able to turn by hand). I do not know what parts this consists of. Am i going to need to replace the entire unit or just the impeller inside, im not sure if the bad impeller will keep the pully from turning with the belt. Engine is a 5.7l mercruiser mag.

 

[dubs283]

Re: Raw water pump is not turning on mercruiser magnum inboard

sounds like the bearing in the pump assy has gone bad

time to replace the whole thing, probably a few hundred for parts

 

[Chaz7R]

Re: Raw water pump is not turning on mercruiser magnum inboard

Took the assembly apart and the impeller pretty much disintergrated inside. After i pryed everything out the pulley seems to turn freely now. So hopefully it was just the impeller not the the bearings in the whole assembly. Sucks though being 4th of July no marinas were open around here day is shot

 

[Don S]

Re: Raw water pump is not turning on mercruiser magnum inboard

After i pryed everything out the pulley seems to turn freely now.

With all the impeller out of it, the bearing should be turning with no feel of roughness at all, if there is, it will probably lock up again.
How old was the impeller? Did you ever start it with no water?

 

[Chaz7R]

Re: Raw water pump is not turning on mercruiser magnum inboard

I bought the boat in april. It has 181 hours on it. Very well taken care of. So I really cant recall what the guy said. The boat is 13 years old so if it was original hours probally wouldnt matter to much. But pulley seems fine so I think ill just replace the impeller for now considering the assemblys ive seen online are going from $425-$500 ouch