Raw water pump failure???

[michaelxmas]

Big problem gang! went down to the boat yesterday and turn over the engine for a little cruz. Started right up but heard a loud squealing from the engine compartment. The engine was turning, but the belt was NOT. Of course I shut it down fast. It looks like the raw water pump pulley is not turning and that is why the belt is not. The 1999 2100v boat only had about 100 hours when I bought it and I just changed the impuller about 200 hours ago? Tt is in salt water, but before I put it in I have a fresh water cooling unit installed on it. I guess I will try pulling the pump off, but WHY would it jam up like that?

[chpthril]

Sounds like the impeller flipped last time the engine was shut down. Sometimes the engine will roll backwards a little upon **** down, this caused the impeller to flip backwards in the housing. Pull the cover and see.

[laserfish]

Have had this experience and when we took the housing apart, one of the vanes of the impeller had come loose and lodged itself in one of the water ports. New impeller and all was good. I now make it an every spring maintenance item to replace it. Not worth a ruined weekend. Now it is just part of the de-winterizing routine. Amazing that it only takes them sitting just a few months to take a set and start cracking. One day I will try one of the "run dry" impellers made by Globe.

[kko]

Because it a mercruiser and thats what they do. I cant really tell you why but I see it alot. installing a freshwater cooling unit as you call it has nothing to do with the raw waterpump salt water still goes through the raw waterpump. 200 hours is alot of time on an impeller how many months/years has it been? On a mercruiser I would change that impeller every year or 100hrs. like I siad they have a much higher failure rate than the crank drivem raw waterpumps/impellers found on indmar and marinepower engines. The pcm belt driven pumps dont seem to fail like the mercruiser ones do either. Its kind of the nature of the beast as they say and changing it once a year is the fix IMPO. good luck.