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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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Jeff, my name is*****'m thinking about changing

Customer Question

Hello Jeff, my name is***** thinking about changing the water pump on my 99 mercury 200. Can you give me some advice? Thanks
Submitted: 2 years ago.
Category: Boat
Expert:  Jeff G. replied 2 years ago.
Welcome,this question may need more than a single answer. Please post back with additional questions on this at any time.
Hi doing a water pump isn't difficult with a few hand tools. I'll give you the basics and if you need more information or don't understand something, just let me know.
Drop the lower unit.
Trim the lower unit up.
Disconnect the battery and spark plug wires.
Put the control in neutral.
Remove the nuts from the front, sides and under the cavitation plate of the lower unit. Remove the trim tab from the back. It is accessed from the small well just above and should have a plastic plug on it. Remove the fastener in the cavity of the trim tab. Note the direction the trim tab is in before removing it.
With all the fasteners out pull the lower unit straight down and off.
Remove the bolts and nuts holding the water pump body on. The pump is around the driveshaft. Note the parts as they come off.
Pull the housing directly off leaving the rubber impeller on the driveshaft.
Now remove the impeller there is a key which may come off with it.
If all you are replacing is the impeller simply slide the new impeller down over the key on the driveshaft.
Put a thin film of grease or dish soap in the cup of the pump housing. Now while turning the driveshaft push the housing down over the impeller.
replace the fasteners holding the pump on.
With that done push the lower unit back into place. Make sure the shift shaft in the front of the gearcase indexes with the female shift shaft in the midsection. There is a water tube in the midsection that indexes into the water pump outlet.
Push the lower unit all the way up. If it doesn't want to go the last inch or so while pushing up on the lower unit have a helper turn the flywheel on top of the engine slightly clockwise. This will index the driveshaft into the crankshaft.
Now in place simply replace the mounting bolts and nuts.
Before reattaching the battery or plug wires, have a helper shift the control to forward, back to neutral and then reverse while turning the propeller to ensure it is shifting properly.
That's about it.
Post back with any questions.