Procedure for replacing impellers on Suzuki DF150/175/250

[matt_unique]

Suzuki DF-150/175/250 Impeller replacement

*Someone on ‘The Hull Truth’ website with the handle of “Flot” initially wrote the following procedure for his DF250. I made edits and additions to the content as I stepped through the process on my DF150’s and double checked the Suzuki Service Manual.

Tools needed:

- Torque Wrench
- Socket Wrench
- Sockets: 12, 14, 17 mm
- 2" socket extension
- Flat wrench 14 mm
- Prop wrench or socket to remove prop
- Pliers
- Needles nose pliers

Materials:

- Couple of rags
- Silicone Sealant (black or clear) Suzuki PN 99000-31120
- Water resistant grease Suzuki PN 99000-25161
- Suzuki water pump kit

Steps:

- Put motor in neutral
- Remove prop - makes life easier by reducing weight - remove cotter pin, use prop wrench to remove nut, pull prop off, set aside
- Tilt motor all the way up
- Use tape or something to mark the exact position of the fin under the cavitation place. Remove "fin" above prop - bolt in the center, takes 12 mm socket
- After removal, you'll see a 17 mm bolt that was hidden. Remove 17 mm bolt using socket wrench with 2" extension.
- Unbolt the (6) 14mm bolts around the sides of the lower unit. You'll find that a normal socket wrench will get wedged between the bolt and the cavitation plate toward the end. Loosen with the socket wrench, finish removing with your fingers or the flat wrench.

Lower unit should now be free but may take a little wiggle effort to pull loose. Be careful with the shift shaft, it is free at both ends, don't bend it. The speedometer water pickup tube will also have to be disconnected after the lower unit drops down about 2”. Pull straight outwards on the lower unit, the driveshaft will be attached. Don't worry about putting the motor in gear etc, just leave it in neutral - the shift shaft is easy to get into place later. Be prepared to hold the 30/40 lbs of weight!

Support the lower unit in something so that you can work on it. A slatted patio table may work well as the skeg can drop right into place. The unit will also sit on the floor (leaning forward) believe it or not. I used two scuba tanks to hold up both sides and used a low stool to do the work in my shed.

Looking down on top of the lower unit, you'll see the water pump assembly held in with 4 bolts, with the driveshaft coming through the center.

- Remove the (4) 12mm bolts keeping the pump assembly together.
- Lift the plastic top case off. What you'll get is the top plastic shell, a metal sleeve inside the shell, and possibly the impeller as well. If any of these pieces stay behind, remove them and set aside.
- Now you are looking down at the driveshaft and a metal plate. There should still be a woodruff key (half circle) inserted into a notch in the driveshaft. Cover all the open holes on the lower unit with duct tape or something before you remove it. The key will fly off and land in one of the holes. Carefully pry the key out with a screwdriver.
- Pull up the metal plate from the lower unit, and the gasket underneath.
- Now that you've removed all the components, clean the surface and remove any leftover gasket material. Grease the whole driveshaft to prevent corrosion and make re-assembly easier. Also, lightly grease the top portion of the speedometer pitot tube.
- Put on the new flat gasket. Holes line up with pins so that you can't do this backwards.
- Put on the new bottom metal plate, as above
- Insert the new woodruff key into the driveshaft notch – use a hammer to tap into place
- Slide the new impeller down onto the driveshaft and over the key. Note that the impeller has a cutout on the inside for the key to fit into. This cutout should be facing down.
- Use pliers to remove the metal insert from the plastic top case you set aside. DO NOT use a screwdriver to pry it out as the edge of the plastic casing will break off.
- Remove the crazy shaped rubber seal ring from the top case and discard. Clean the inside of the plastic case.
- Lightly grease the inside of the plastic case, and insert the new rubber seal ring into the indentations inside
- Clean and remove any leftover material inside or outside the metal cup. Lightly grease the OUTSIDE of the metal cup. Push the metal cup back into place, being careful not to pinch the rubber ring. The metal case will fit snugly and there is a tab on top that will line up with a notch in the housing. Use pliers to try to rotate the metal cup to ensure the tab is in the slot.
- Lightly grease the inside of the metal cup and the bottom metal plate, so the impeller can spin freely.
- Slide your top case assembly back down the driveshaft. Once it contacts the impeller, begin turning the driveshaft clockwise as you push downward. This is important - it will set the vanes of the driveshaft in the correct direction. This is surprisingly easy if everything is greased.
- Hold the top case down, and put the 4 pump case bolts back into place. Use the torque wrench to tighten these to 17 Nm / 12.5 ft-lb.

Your lower unit is 100% assembled and ready to put back on.

- Grease your driveshaft splines, and also the male and female ends of your shift rod. Clean out any corrosion along the way. VERY IMPORTANT: Use plenty of grease on those driveshaft splines as they are a potential problem area
- Insert the shift rod back up into the midsection - you can see it come through the top of the midsection under the center of the motor. It should go into place easily; the flat portion of the rod should face aft with the engine in neutral. It should stay there with friction/grease.
- The Suzuki service manual recommends applying a "light coating of silicone seal to mating surfaces of gearcase and driveshaft housing" I presume this forms a gasket of sorts, so I did it, all around the edge of the lower unit, and all around the edge of the midsection
- Muscle the lower unit back into place. This is possible solo, but is probably easier with a helper. If you left everything in neutral, the shift rod should slide back into place easily as well. Use needle nose pliers to reattach the speedometer hose after the lower unit is bolted into place. You can see if the speedometer hose is connected by looking through a small hole under the cavitation plate. Give it a light tug to make sure it’s connected as well.
- Tighten the 7 bolts holding the lower unit to the midsection. According to my service manual, 10mm bolts get 55N-m (40 ft-lb), and 12mm bolts get 83 N-m (60 ft-lb). Suzuki also recommends applying silicone sealant on these bolts.
- This is a good time to test your shift lever to make sure the lower unit goes in and out of gear properly
- Put the fin back on above the prop
- Re-install the prop if removed

That's it!

Here is a picture of the lower unit components for reference.

--Matt

[stlof]

Good stuff, thanks.