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View Full Version : 1989 YAMAHA 8 HP WATER PUMP REPLACEMENT



JOHN FORGIONE
02-08-2004, 04:57 PM
" JOE AND TONY,I OWN A 1989 8 HP YAMAHA MODEL#8SD SN 041730 CODE#6G1S ,I NEED INSTRUCTIONS ON CHANGING WATER PUMP IMPELLER.i read your advice on same engine,but,could not connect to YAMAHA SITE, PLEASE SEND ADVICE.THANK YOU,JOHN "

JOHN FORGIONE
02-08-2004, 05:02 PM
" great site ,thank you "

tonyob
02-09-2004, 11:11 AM
" John,

I will take a look at that engine today and give you some pointers later, if someone else does not get to it first.

Tony "

tonyob
02-10-2004, 10:51 AM
" John,

This is not a very tough job. First you must loosen the clamp that joins the upper and lower shift rods, located at the front edge of the mid-section, just above the top edge of the gearcase.

There should be two screws on either side of the gearcase, and one under the trim tab at the rear of the gearcase, securing the gearcase to the mid-section.

When you have removed these screws the lower unit will come off. Sometimes the driveshaft can be tough to pull out. If you are having trouble separating the lower from the engine, the driveshaft is probably the problem, but usually it just comes right off.

Once the gearcase has been removed you will see the water pump on top of the gearcase, secured by four screws to the top center of the gearcase.

After removing the four screws, the water pump can be removed from the gearcase. Sometimes the impeller can be frozen on the shaft, and difficult to remove, but it can be broken easily with a chisel or hacksaw. If you have to do this, first cut the rubber off of the central sleeve, and then break this sleeve without damaging the driveshaft.

Remove the base plate and gasket, and clean the top of the gearcase and water passage thoroughly.

Use a little gasket sealer on the gasket and plate during reassembly.


Grease the inner surface of the chrome insert and insert the impeller while turning it counter-clockwise ( as viewed from the bottom of the insert ). Make sure all of the blades are bent in the same direction. Put some gasket cement on the outer surface of the chrome insert and insert it into the plastic housing. Let this sit until the gasket cement hardens. This makes it easier to slide the housing/impeller assembly over the driveshaft and down onto the gearcase.

Place the locking pin on the driveshaft and use a little grease to hold it in place as you slide the housing and impeller over it. You may have to hold the pin in place with a thin screwdriver while doing this. Press the housing all the way down and install the screws and side plates. Tighten the screws evenly and turn the driveshaft clockwise ( as viewed from the top ) every so often as you tighten down on the screws.

Before installing the gearcase, you should attatch a water hose to the water tube to see if the cooling system is clear. If the old impeller was broken there may be some pieces of it clogging the tube or block. Running water through the system will indicate if there is a problem. You can even run the engine with this water hose connected if you think that there may be a cooling system problem. If the engine overheats when test running like this, you have to find the problem before installing the lower unit.

When you are ready guide the driveshaft into the mid-section and the water tube into the grommet on top of the water pump. If you have trouble with the driveshaft, you might have to turn the flywheel clockwise so that the splines line up. Guide the shift rod through the coupling, and after tightening the screws that secure the gearcase, you can tighten the shift rod coupling. Just make sure that the shift handle and the gearcase are in the same gear when you tighten the coupling.

If you run into any trouble let us know.

Tony "

batman
05-23-2004, 01:25 PM
9.9 Yamaha 1987- I have a water/oil mix coming out the breather holes on top of my gear case. Does anybody know what is going on here? I recently replaced my water pump. Could the two be connected?

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