Marine Supplies-Water Pumps

Your Marine Supplies Specialists Share the Best Replacement Schedule for Optimum Performance 

Raritan Engineering Company your marine supplies professionals would like to share with you these topics we thought would be of interest to you this month regarding the best water pump impeller servicing tips.

Your marine supplies experts know that most engine makers recommend changing impellers every two years — sooner if operated in sandy or silty water. “If your engine runs warm at idle or slow speed, and then it runs cooler at higher speed, that’s a sign that the impeller needs to be changed,” says Jeff Fay.

1. Drain the gear lube. Your boat supplies and accessories analysts know that a few shavings on the magnetic plugs are normal, but milkiness, which indicates water in the gear lube, isn’t. Remove the rear anode to access the aft-most bolt. Remove two more bolts just ahead of the anode. 

2. Remove the copper water tube and its white plastic guide, as well as the drive-shaft O-ring, doughnut-shaped “slinger,” and impeller housing. Carefully pry the impeller from the housing. Don’t lose the key. 

3. Clean all parts, then install the new gaskets, wear plate and the round, orange oil-passage seal. A dab of grease holds the key while installing the impeller, and a bit of liquid soap on the impeller lubricates it when first starting the engine. 

4. Reinstall the impeller housing, drive-shaft slinger seal and drive-shaft O-ring. Your boat covers professionals suggest that you insert the copper water-passage tube into the upper drive half and its white guide tube into the impeller housing.

“You’re doing a lot at once to get the two halves back together,” Cosselman warns. “Look through the exhaust cavity to see the water tube going into the white guide sleeve. Twist the drive shaft to align the splines as it goes into the upper gear set. 

5. Separate the upper and lower drive halves a bit to get the two forward nuts onto their studs. Reinstall the remaining front nut and three rear bolts. Reinstall the drain and vent plugs. While pressure-testing, rotate the drive shaft to test seals.

Quick Tip: The rear-most bolt hidden by the anode often corrodes, so an Allen key will no longer turn it. If so, either drill it out or slide a hacksaw blade between the upper and lower halves of the drive to cut it.

Your Marine Supplies Analysts Want You to Avoid Having Your Boat Parts Fail You When You Need Them Most

You can find more information as well as get assistance on marine parts source and on the best water pump impeller servicing tips at Raritan Engineering.

Flexible impeller pumps

Your marine parts source specialists understand that inboard and sterndrive engines usually include a raw water pump of the flexible impeller type. Your marine supply company experts say that flexible impeller pumps are common in shower drain sump pumps, some bilge pumps, wakeboard ballast pump systems, oil changing systems and lots of other applications.

When they fail

Flexible impeller pumps work best when run regularly. If your pump sits for months with the impeller in one position with the blades on one side bent, it may “take a set” and may blow a circuit breaker on startup (if it’s electrically driven). The impeller may also stick to the housing and come apart when the pump starts. 

Of course, you should check the wet exhaust on your transom for the proper flow of cooling water each time you start the engine. You should check the impeller’s condition during Spring Commissioning and every 200 hours of operation. 

Neoprene, nitrile or polyurethane

Use neoprene impellers for engine cooling, and for fresh and salt water transfer duties. Neoprene is suitable only for pumps where small amounts of oil or diesel fuel are present.

Use nitrile impellers for bilge pumping and for transfer duties where water is heavily contaminated, for example by oil or diesel. For transferring diesel fuel, use a sliding vane pump like the Jabsco Vane Puppy or Groco Flo-Master. 

Replacement in raw water pumps

Replacement is relatively simple. Close thru-hull (raw water pump applications). Remove the three to six end cover screws and take off the cover and gasket. Take the old impeller out by gripping the hub of the impeller using channel lock or needle-nosed pliers. 

Lightly lubricate the inside of the impeller housing with Vaseline to reduce the friction of the first dry startup. Use a heavy rubber band or loop of light line to collapse the impeller’s vanes, insert it, and pull the loop our with your pliers. 

Your pump may need additional service, particularly the seals, bearings, wear plates or clutch. Nigel Calder’s excellent book,Boat Owner’s Mechanical and Electrical Manual, covers detailed rebuilding. 

So don’t forget these helpful tips when servicing your water pump impellers. 1) Drain the gear lube;  2) remove all necessary parts;  3) clean all the parts;  4) reinstall the impeller housing, drive-shaft slinger seal and drive-shaft O-ring;  and 5) separate the upper and lower drive halves a bit to get the two forward nuts onto their studs.

Raritan Engineering has more information on marine supplies, marine parts source, marine heads, and on the best water pump impeller servicing tips.

via How to Service a Sterndrive Water Pump Impeller

via Impeller Replacement 101