Melted water pump

[Jme152]

1989 Maxum 1900, Mercruiser 5.0LX paired with an alpha 1 outdrive. Recently the boat overheated and I noticed a crack in one of the exhaust manifolds (it wasn't winterized the last 2 years). The motor survived with no internal damage. I did find that the water pump in the outdrive was completely melted. I've already replaced everything but my main question is, what caused this and is there anything else I should look for? Thanks in advance.

Jeff

 

[JoLin]

The outdrive's impeller melts when the engine is run without a water supply to the outdrive. Normally happens when the engine is started 'dry', with no muffs on the outdrive. It only takes a minute to destroy the impeller.

 

[Scott Danforth]

Not even a minute. If started dry and the drive was sitting for a few days its only a matter of seconds before the impeller melts.

With that significant of an overheat, make sure you also replace the exhaust flappers and exhaust hoses

 

[tpenfield]

:welcome: to iBoats.

Did just the impeller melt, or was it the whole pump body? Sounds like that is what you described.

Tell us more about the crack in the manifold(s) and the lack of winterizing. How do you know the cracks are limited to the manifolds and not the engine block. :noidea: