Jet Ski Impeller and Wear Ring Replacement (What's Involved)

Track top speed (GPS or the craft's display) and top RPM on a calm day with the same load and fuel. When the craft is new or freshly serviced, write them down in BoatMend. A slow drop in speed with RPM staying the same or climbing is the classic sign of wear.

Put the craft on its trailer on level ground. Remove the lanyard or key fob and disconnect the battery. Rinse the pump area with fresh water so you can see clearly. Tilting the craft (on a proper stand or with the trailer's tongue lowered) gives a better view up through the grate.

Look up through the intake grate and in through the nozzle. Remove weeds, line and plastic with a blunt hook, not your fingers. SBT points out that fishing line wrapped around the driveshaft in front of the impeller can melt from friction and fuse in place, so it may need to be cut away in pieces. If the grate is clean and the shaft area is clear, the problem is inside the pump.

Have a Sea-Doo with iDF? Some recent Sea-Doo models have iDF (Intelligent Debris Free), which Sea-Doo describes as a push-button system on the handlebars that briefly runs the pump in reverse to clear a clogged intake without getting in the water. Use it the way your owner's manual describes when weeds or a bag clog the grate on the water. It's meant for intake debris; if performance doesn't come back, a stone wedged against the wear ring or a damaged impeller still needs the checks below.

Sea-Doo's pre-season checklist says to inspect the wear ring and impeller for deep scratches, nicks or unusual grooves. Use a flashlight and photograph the blades through the grate and nozzle. Look for:

• Chipped, bent or rolled blade edges (rock damage)
• A dull, rounded leading edge (sand wear)
• Deep grooves or gouges in the wear ring
• A gap between blade tips and ring that looks bigger than it used to, or uneven around the circle

Impros, an impeller repair shop, notes that even slight visible damage to an impeller can change performance a lot.

• Small dings, ring looks fine: some impellers can be dressed or professionally repaired.
• Worn or gouged wear ring, impeller OK: the wear ring is the usual fix and is the cheaper part. Sea-Doo lists wear rings among normal wear items (like filters and gaskets) that need replacing over time even with proper care.
• Damaged or worn impeller: repair (reshaping, welding and balancing at a specialist) or replace.
• Uneven gap or shaft play: bearings or the driveshaft may be worn; a new wear ring alone won't fix it.

Order parts for your exact make, model and year. Impellers come in different designs and pitches matched to each engine, so swapping in a "close enough" impeller can hurt performance or overrev the engine.

The exact steps differ by brand and model; follow your service manual. In general, SBT describes the sequence as:

• Disconnect the steering and reverse cables from the nozzle and reverse gate
• Mark how the driveshaft coupler lines up, if your model has one
• Remove the pump mounting bolts or nuts in the hull tunnel
• Slide the pump straight back out of the tunnel, breaking the old seal without prying on finished surfaces

On some models the ride plate and intake grate come off first. Have a clean bench ready and keep fasteners in labeled bags.

Most PWC impellers thread onto the pump shaft. Removing one needs a tool to hold the shaft and a tool that fits the impeller's splines or flats; brands use different tools and some threads can be very tight after years in salt water. Don't use a pipe wrench on the blades or clamp the shaft in a vise without the right adapter. This is where most DIY pump jobs stall: if you don't have the right tools, stop here and take the pump to a shop.

With the impeller back in the housing (or using the method in your manual), measure the gap between the blade tips and the wear ring with a feeler gauge at several points around the circle. Compare with the limit in your service manual; it varies by pump design and size, so don't use a number from a forum. SBT notes that a gap that's tight on one side and loose on the other points to a bent shaft or worn bearing, not just a worn ring.

Wear rings are pressed or bonded into the housing. Removing one often means pressing it out, or carefully cutting it without scratching the housing bore. The new ring has to go in fully seated and square. SBT warns that a ring that goes in cocked will wear unevenly again almost immediately. Some shops machine or replace the whole housing.

While the pump is apart, check the pump shaft bearings and seals for roughness, play or water in the lubricant. Many pumps have bearings in a housing filled with a specific oil or grease and sealed with O-rings and a cap (often called the cone or cover). Use only the lubricant type and amount in your service manual, replace the O-rings, and don't overfill. Milky or watery lube means a seal is leaking and the bearing kit should be replaced. Also check the driveshaft seal and boot where the shaft passes through the hull; a leaking shaft seal lets water into the hull.

Install the impeller with any thread locker the manual calls for and torque it to spec with the holding tool. Spin it by hand: it should turn freely without touching the ring. Clean the old sealant off the hull and pump mating surfaces, apply new sealant where the manual specifies, line up the coupler or driveshaft splines and slide the pump home. Torque the mounting fasteners in the order and to the values in the manual. Reconnect the steering and reverse cables, then check that the nozzle turns fully left and right and the reverse gate works, with the engine off.

Reconnect the battery. Don't "test" the pump by starting the craft on the trailer: Sea-Doo says never to run the engine out of the water, because even closed-loop cooled models need the ride plate submerged to shed heat. Before the first ride, launch the craft and let it sit in the water for a few minutes, then open the seat or engine cover and look for water coming in around the pump and driveshaft. Start it and check the pilot (cooling) water stream. On a short, gentle test ride, check steering and reverse, then compare hole shot, top speed and RPM with your baseline. Check the hull for water again after the ride. Log the work, parts and new numbers in BoatMend.