Raw Water Pump on Merc 454

[dollelliott]

I had a new raw water pump installed several years ago on my 1998 Merc 454. I experienced the usual catastrophic failure of the pump with shredded vanes, etc. When I attempted to replace the rubber impeller I discovered that the replacement unit was composed of an impeller which was vulcanized on the shaft rotor. No key way, no replaceable impeller. Are all new raw water pumps similar or can I find a pump with a replaceable impeller? Must the housing as well as the impeller be replaced? Is there a replacement Jabsco unit with a replaceable impeller? What service life can I expect with a new unit?

 

[jtybt15]

I don't want to get into a rant about merc. Is your fuel pump separate from the water pump? If so, I would go to a crank mounted pump as in Volvo's. I would have gone that route except I went with the bravo style Jabsco pump 15+ years ago and it just won't go away.

 

[dollelliott]

The mechanic said that the impeller was stuck to the shaft and required a "puller" to remove the remains from the shaft.
The housing was quite rough on the interior and needs replacement. I note that there is a brass housing for about double the price. Can this brass housing simply replace the plastic housing for greater durability? Can it be mounted to the existing mounting plate? Is a new pump plate and pulley required? How many hours use does Mercruiser suggest before replacement?