How to Install a Water Pump on a ZX636 Ninja


Kawasaki's ZX363 Ninja was sold in the U.S. between 2003 to 2006 and was designed as the successor to Kawasaki's previous ZX-6R models. The 636 moniker was derived from the inline ffour-cylinder engine's unusual 636 cc displacement, when most comparable sport motorcycles only had a 600 cc displacement. The 636 could be separated into two generations; the 2003 and 2004 ZX636B series, which feature angular body lines and the typical side-mounted muffler, and the 2005 and 2006 ZX636C that boast a curvier body and an undertail-mounted muffler. Both generations relied on a combination water and oil pump, with the containers for the liquids stacked on top of each other, on the left side of the engine. Antifreeze leaks from the bottom of the water pump or the presence of antifreeze in the engine oil are signs that the water pump needs to be replaced immediately.

Things You'll Need

  • Rear swingarm stand
  • Metric Allen wrench set
  • Flexible funnel
  • Drain pans
  • Metric socket set
  • Ratchet
  • Shop towels
  • Torque wrench
  • Flat-head screwdriver
  • Ethylene glycol antifreeze
  • Distilled water
  • One-gallon plastic container
  • 3.5 quarts of SAE 10W-40 motorcycle-grade oil
  • Mount the motorcycle on a rear swingarm stand to support it in an upright, level position. Let the engine cool for a minimum of two hours.

  • Remove the bolts attaching the lower fairings to the left and right middle fairing panels, using an Allen wrench. Remove the lower fairings, as a whole, from the bottom of the motorcycle.

  • Remove the left and right middle fairing panel, using an Allen wrench, to expose the radiator cap on the right side of the motorcycle and the water pump on the left side of the engine.

  • Turn the radiator cap counterclockwise until it stops. Push the cap down, then turn it counterclockwise until it can be removed from the radiator filler neck.

  • Hold a flexible funnel below the engine cylinder coolant drain bolt, located at the lower edge of the left cylinder head, just above the left crankcase cover. Position the funnel's outlet in a drain pan placed below the engine. Remove the cylinder drain bolt with a ratchet and a socket. Let the antifreeze drain until it stops completely. Wipe away any residual antifreeze with a shop towel, then screw the drain bolt into place by hand. Tighten the drain bolt to 87 inch-pounds, using a torque wrench.

  • Remove the water pump drain bolt located at the bottom of the water pump behind the left crankcase cover, using a ratchet. Let the antifreeze empty into the drain pan until the flow reduces to a light drip. Set the drain bolt aside for later use.

  • Unbolt the coolant reserve tank, located behind the inner fairing panel on the right side of the motorcycle, using a ratchet. Pop the lid off the tank, then turn the tank upside down over the drain pan until all the remaining antifreeze has drained. Reinstall the reserve tank and tighten the tank mounting bolts until they are snug.

  • Place a second drain pan directly below the engine. Unscrew the oil filler cap from the top of the right crankcase cover by hand. Remove the oil drain bolt from the bottom of the crankcase, using a ratchet. Let the engine oil drain to a light drip, then wipe away the remaining oil. Screw the drain bolt into place by hand, then tighten the bolt to 22 foot-pounds.

  • Loosen the clamps securing the coolant hoses to the top and bottom of the water pump cover, using a flat-head screwdriver. Pull the hoses off the water pump cover spigots. Remove the remaining two bolts securing the water pump cover to the crankcase, using a ratchet. Pull the water pump cover off the crankcase. Remove the water pump O-ring, which should still be attached to the crankcase, and discard it.

  • Hold the water pump impeller with one hand and unscrew the impeller bolt with a ratchet. Remove the impeller washer and the impeller from the water pump shaft by hand. Inspect the impeller for damage, such as cracked or missing fins. Replace the impeller if it is damaged in any way.

  • Screw the impeller bolt halfway into the end of the water pump shaft. Grasp the bolt head and pull the water pump body out of the crankcase. Remove the O-ring that seals the water pump body from the oil pump and inspect it for wear or damage that could allow oil and antifreeze to pass between the oil and water pumps. Replace the O-ring if it is damaged. Unscrew the impeller bolt.

  • Pull the ‌inner oil pump rotor and the oil pump cover, located at the rear of the water pump body, off the water pump shaft. Pull the water pump shaft out of the water pump body. Inspect the water pump body and oil pump cover for deterioration around their outer edges, as well as for holes or cracks that could allow antifreeze and oil to pass through it. Inspect the inner oil pump rotor for damaged fins. Inspect the water pump shaft for scoring or grooves that could create a leak. Replace the water pump body, water pump shaft, oil pump cover and inner rotor if they are damaged in any way.

  • Pull the outer oil pump rotor out of the crankcase and inspect it for wear or damage. Replace the rotor if it is damaged.

  • Push the water pump shaft through the water pump body. Slide the oil pump cover over the rear end of the shaft, followed by the inner oil pump rotor. Push the outer oil pump rotor into the crankcase, followed by the water pump body and the attached inner oil pump rotor and oil pump cover.

  • Spread a light coat of ethylene glycol antifreeze around the rubber seal at the rear of the impeller, then push the impeller over the water pump shaft. Install the washer and impeller bolt by hand. Hold the impeller in place, then tighten the impeller bolt to 87 inch-pounds. Reinstall the water pump cover O-ring and the water pump cover. Tighten the cover bolts, including the drain bolt, to 104 inch-pounds. Push the coolant hoses onto the water pump cover spigots, then tighten the hose clamps.

  • Mix two quarts of ethylene glycol antifreeze and two quarts of distilled water in a one gallon plastic container. Fill the radiator with the antifreeze mixture until the antifreeze level is at the bottom of the radiator filler neck. Do not reinstall the radiator cap at this time.

  • Fill the coolant reserve tank to the "full" mark imprinted on the side of the tank, with the mixed antifreeze.

  • Fill the engine with 3.5-quarts of SAE 10W-40 motorcycle-grade engine oil through the filler neck on top of the right crankcase cover. Screw the filler cap into place by hand.

  • Start the engine and let it idle. Watch the radiator filler neck for bubbles rising up through the antifreeze. Tap on the radiator hoses to free any trapped air. Stop the engine when bubbles no longer appear in the antifreeze. Refill the radiator to the bottom of the filler neck, then reinstall the radiator cap.

  • Start the engine again and let it idle. Stop the engine as soon as the radiator fan activates, then let the engine cool for a one hour.

  • Check the antifreeze level in the coolant reserve tank. Add antifreeze to raise the fluid level to the "full" mark, if needed.

  • Reinstall the right middle fairing and lower fairings. Lower the motorcycle onto its side stand.

Tips & Warnings

  • Do not reuse the antifreeze or engine oil, especially if you suspect that the water pump or oil pump are damaged. Contaminated oil and antifreeze can create problems within the cooling and lubrication systems that will result in engine failure.
  • Transfer the old antifreeze and engine oil into resealable containers immediately after completing the repair. Store the containers in a safe area, out of the reach of children or animals, if you cannot immediately take the fluids to an automotive fluid recycling center.

Related Searches


  • 2004 Kawasaki ZX-6R Ninja Motorycle Service Manual; Kawasaki Heavy Industries
  • 2005 Kawasaki ZX-6R Ninja Motorycle Service Manual; Kawasaki Heavy Industries
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