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Jeff G.
Jeff G., Marine Mechanic
Category: Boat
Satisfied Customers: 4728
Experience:  42 years experience, Certified Master Technician, All Major Outboards, Sterndrives, Hi-Performance
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JA: . What is your issue regarding? Customer: I have a 1960

Customer Question

JA: Hi. What is your issue regarding?
Customer: I have a 1960 Merc 400 short shaft 45 hp. I was about to replace the impeller and notice gearbox oil in the impeller housing and also in the cooling tube going to the power head. I had noticed the gearbox contained only water at the end of the season. So I need to replace the shaft seal, or the entire water pump housing. How do I do this? Thanks.
JA: Sometimes boat issues seem like they'll be really complicated, but end up being easy to fix. The Marine Mechanic I'm going to connect you with knows all the tricks and shortcuts. Is there anything else the Marine Mechanic should be aware of?
Customer: No, and thanks.
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Submitted: 1 year ago.
Category: Boat
Expert:  Jeff G. replied 1 year ago.
I'll need the serial number to positively ID the engine. However the seals for the driveshaft have gone bad. As the water pump pressurizes the water it is forcing it into the gearcase and forcing the gear oil out. Under the wear plate that the impeller rests on is the water pump base, this is where the seals are located. Simply pry up with two large screwdrivers, CAREFULLY to remove the housing then punch the old seals out and then tap new ones in.Look carefully at the driveshaft where the seals ride. If it is severely pitted then a new seal won't do you any good, it will continue to leak.Put a new seal and O ring on the base, put some grease on the seal and O ring and gently tap it back into place.We always pressure test the gearcase as well. Your local Mercury dealer can do that probably for just a couple dollars.Let me know if you have more questions on this or need further help. If so enclose the serial number.Thanks