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Slow Engine Cranking

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DRK82

New member
Just rebuilt lower unit water pump. New impeller was properly lubricated and installed with vanes correctly set (counterclockwise as view from bottom, clock wise as viewed from top) It was a very snug fit in pump housing. Engine now cranks slower than before. Is it possible for a new impeller to cause this before it is broken in ? Alpha One with 3.0 Mercruiser.
 
only if you assembled the pump incorrectly. Simply replacing the pump has no effect on cranking speed
click to enlarge #41 goes above the housing not under the housing. called the " slinger"

 
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Put mine together correctly with #41 inside pump housing. Puzzled as to why they describe this as a "slinger" as opposed to shaft seal, etc.
 
DRK82 said:
Put mine together correctly with #41 inside pump housing. Puzzled as to why they describe this as a "slinger" as opposed to shaft seal, etc.
Click to expand...
Its not a shaft seal, it’s not supposed to touch the housing. The merc impeller kit cones with a fixture to slide the slinger down the drive shaft and correctly position the slinger just above the stainless water pump housing. The slinger is designed to keep any water and exhaust gas in this cavity off the shaft and out of the impeller. Raised concentric rib on the side of the impeller is what seals the impeller to the housing.

if you installed this inside the housing and jammed it in there by screwing the housing down, you need to remove it and likely get a new slinger.
 
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