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Sherman has over 19 years experience in the marine business as a Mercury - M/C Certified Technician.
He has operated his own shop since 1998, providing repairs, parts and accessories. In 2003 Sherm opened Sherm's Marine and is a full service Mercury and BassCat dealer.  
Sherman will be sharing some very good tips and detailed articles on the various repairs/maintenance that you can perform yourself. 
Most will have photos included.
** Check out Sherm's Website !!

Sherm's Marine
Sherman Truss
8662 South - 400 W.
Wabash, IN 46992

Phone: 260-563-8051  Fax: 260-563-8748
Sherm's Marine

E-Mail: Shermsmarine@omnicityusa.com

** Click here for "Hot Foot Installation"  

  Wheel Bearing & Brake Maintenance

2/10/02   3.0 L Water Pump Replacement

Mercury Water Pump Replacement
(This will cover most all models.)
** Click here for 3.0 L engines

** Click here for Printer Friendly Version

This is a job that can be done with common tools and in less than an hour.
** Remember, safety first!**

Step 1: Remove the ignition key.
Step 2: Remove cowling, then all spark plug wires from plugs, then all
spark plugs.
Step 3: Make sure gear housing is in Neutral.
Step 4: Tilt motor to full up position and engage the tilt lock lever.
Step 5: Disconnect the pitot hose (speedometer) and remove propeller,
(makes it easier to do next step).
WP2.jpg (25236 bytes)  Photo 1 - Step 5 - Removing the prop using a 2 x 4.
* Click on thumbnails for large photos.
Step 6: If you have a trim tab, mark it and the housing so you can put it
back in the same location for reinstallation (grease pencil works well).
If you have a flat anode plate this is not needed.
Step 7: Remove the plastic cap at the rear edge of driveshaft housing so you can remove the bolt holding the trim tab.
Step 8: With trim tab removed, remove bolt inside trim tab cavity.
Step 9: Remove two lock nuts/washers from bottom middle of anti-cavitation plate.
Step 10: Remove locknut and washer or plate from front gear housing stud.
Step 11: Loosen the 2 side locknuts.  Both nuts must be loosened sufficiently before either one can be removed and the housing will be loose at this point.
WP1.jpg (54756 bytes) Photo 2Steps 7 to 11 -  Indicates the nuts/bolts to be removed.
Step 12: Pull gear housing as far away from drive shaft housing as you can then remove the loosened nuts.
( Be careful...it's now free, so don't
let it fall!)
**Note: As you remove the gear housing from drive shaft housing, watch for the possibility of the water supply tube to stay in water pump housing as you remove the gear housing. IF it does, go ahead and remove gear housing then remove the water tube from water pump housing and re-install it back into drive shaft housing and into powerhead grommet.
(You will have to push it back up into rubber grommet). It should stay at this point, (you will need a flashlight to see up to grommet.) 
WP3.jpg (37127 bytes)  Photo 3 - Steps 12 to 16 
 Removing the water pump housing.

Step 13: Mount the housing on something that will hold it in a sturdy upright position.
Step 14: Now we're ready to remove the water pump housing.
To do this, remove the 3 nuts/washers and 1 bolt.
Step 15: Remove the water guide tube and slide the rubber slinger up the driveshaft to remove it.
Step 16: Using 2 small pry bars (medium size screwdrivers will work), lift the waterpump housing up and slide it up and off of driveshaft.
(If the impeller goes up with it, watch for the key.)

WP4.jpg (17811 bytes)  Photo 4 - Top row shows the old impeller, new impeller, key, nuts & washers and screw.
Second row shows the WP housing & guide tube.

Step 17: Remove the impeller the same way as you did the housing by sliding it up and off the driveshaft (may have to use a pry bar if it is stuck in place). Remove the key.
Step 18: Inspect pump housing for cracks and the stainless insert for wear.  If it has any it will also need to be repaired or replaced.  Also check the face plate (located under the impeller) for signs of wear.
(If you remove the plate you will need to replace all the gaskets.)
Step 19: If all is ok, (and/or you you have repaired/replaced them), then it's time to start reassembly.
Step 20: If removed, slide the gasket/face plate down the driveshaft into position then gasket onto studs, then the key (make sure it is in flat of driveshaft, using a small amount of grease will help hold the key in place.)
Step 21: Now slide the new impeller down onto the key. (Make sure the key and keyway in impeller hub align together.)

WP5.jpg (34989 bytes)  Photo 5 - New Impeller in place and ready to go back

Step 22: Put a VERY light coat of grease on water pump housing insert,
(just enough to help impeller slide into housing.)
Step 23
: Slide housing down to the impeller and studs, now turn driveshaft
CLOCKWISE (viewed from top), with one hand as you push water pump housing down over impeller & studs.

WP6.jpg (30465 bytes)  Photo 6 - Installing the housing...push down as turning
                 driveshaft clockwise.

Step 24: Put nuts/washers and bolt back on and tighten. (DO NOT OVER TIGHTEN as you can damage housing. Torque spec: 50 in. lbs. on nuts, 35 in. lbs. on bolt.)
Step 25: Reinstall the rubber sling washer & guide tube.  Also make sure that the bolt for trim tab/anode plate is still in place.
Step 26: Put small amount of grease on drive shaft splines, (keep it off the top, do sides only) and also put small amount on shift shaft (same as drive shaft, sides only).
Step 27: Shift control box/motor into forward gear.  Next, slide prop back onto prop shaft (no nut). Take pliers and as you turn prop counter-clockwise turn shift shaft clockwise until in full forward gear.
(Do not turn prop clockwise).

Step 28: We're now ready to install gear housing back onto drive shaft housing, so position gear housing so the drive shaft protrudes into the housing and you have to make sure the supply tube from power head starts into the guide tube on pump.
Then, as the drive shaft gets up to the power head you will need to turn counter-clockwise to align splines of drive shaft and crankshaft.
Also, you must check that the shift shaft from gear housing to shaft in driveshaft housing slide together properly.
Once everything is aligned the gear housing should fit back up against the driveshaft housing.

WP7.jpg (36447 bytes)  Photo 7 - Re-installing the gear housing.
Step 29: Install the 2 side locknuts (gear housing will have to be away from driveshaft housing a small amount for clearance for the nuts to fit over the studs).  Once both nuts are in place, push gear housing back tight against and snug up the 2 nuts.

Step 30: Check shifting operation by putting control box/motor back into neutral.  Prop should turn freely in both directions.  If not, have the shift shaft off and you must redo Step 28.
Step 31: Once all checks out ok, install the 2 locknuts in back under the cavitation plate.  Then the 1 bolt in trim tab cavity.  Then the locknut/washer on front stud.  Now tighten all 6 nuts/bolts to 55 ft.lbs, then install trim tab/anode plate.  Reconnect pitot hose.
Step 32: Slide prop back off, grease propshaft splines, then reinstall.
Thrust washer, prop, washers & nut. Torque to 55 ft. lbs. (piece of wood - 2x4 works good while tightening nut).

WP2.jpg (25236 bytes)  Photo 8 - Re-installing the prop.
Last Step: Reinstall spark plugs and wires.

Job is done and ready for a test run!!
Any questions?   Sherman Truss

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