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Old 09-05-2017, 08:58 AM   #5
Maerin's Avatar
City: East Coast
Country: USA
Vessel Name: M/V Maerin
Vessel Model: Solo 4303
Join Date: Jun 2013
Posts: 825
Originally Posted by Sagdito View Post
I have a very small oil leak coming from my fresh water pump on one of my Cummins 6BTs, now how can this be, as I would have thought there is only cooling water anywhere near the pump. Its coming from the base of the pump where it bolts onto the block.
Any ideas
Engine circulating pump is on the front of the block, about in the center. It is driven by a serpentine belt that rides on a smooth cylindrical drive about 2-1/2" in diameter.

The seawater pump is mounted on the timing gear train case, it is gear driven, there are no moving parts visible. It mounts just below the fuel injection pump, held in place with 2 bolts.

The engine pump should not leak oil, there's no oil in contact with any of the internal parts, only engine coolant.

The seawater pump could leak oil if the large (about 4" dia) gasket between the gear case and the pump mounting plate is leaking, there are also shaft seals that keep the oil on the gear side of the housing, they could leak. Case gasket is simple to replace, if the shaft seals are leaking, the pump should probably be rebuilt, or a new one, depending on hours, condition.

I keep a replacement pump ready to go, swap out the whole pump then service the removed pump at convenience. My current pump has over 2000 hrs. Impeller is about due has about 600 hrs.
Steve Sipe
Selene 4303 Maerin
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