See full version: Outboard Expert: Water Pump Impellers
This Mercury outboard water pump was run dry briefly, and the impeller literally melted within the housing. You can see the imprint of the impeller on the back. In this case the entire water pump was replaced. [links]
The impeller to the right is new. The two to the left are old, with vanes that are worn, hard and curled over from sitting idle for years in an older motor.
“Another issue is owners think they can start the motor if a hose is hooked up to the flush port,” says Greenwood. “That pushes water through the powerhead and exhaust, but very little gets to the pump. We tell owners to always use a set of water muffs on the gearcase if they want to start the motor with the boat on a trailer.”
The water pump impeller of any outboard motor needs to be serviced on a regular basis, a task that if overlooked can lead to big trouble. Most outboard maintenance schedules call for inspection of the impeller every 100 hours, or once a year. And once you’ve paid a tech to drop the gearcase and look at the impeller, you might as well spend another $25 and get a new one installed. The entire job is about $100 of cheap insurance. here
Pieces of the broken impeller can end up in the heat exchanger or cause blockages in other parts of the engine. This can require major parts of the engine to be stripped down so these blockages can be cleared and the rest of the engine can be checked for small fragments of the failed impeller. here
How long does Mercruiser impeller last? Mercury recommends changing impeller every 3 years. here
Signs of a bad boat impeller are either boat engine overheats when you try to accelerate, loss in impeller vanes flexibility, physical wear & tear like cracks in impeller vane roots, melted or worn of vanes. Even if you see less or no water coming out of tell-tale, it might be due to a bad impeller. here
Most mechanics and manufacturers recommend every 3 years more because you don’t want the bolts on your lower unit to cease up more than the actual wear to the impellor. [links]
It is located just above the lower gear case assembly, making it easy to service. Inside the pump housing, there is a rubber impeller that is keyed to the driveshaft. As water enters into the lower gear case via the inlets on the side of the lower unit, the driveshaft will turn the pump impeller.
More than anything else, bad visuals tell you more, and you can decide on that factor most times. You can decide that by just looking at the impeller, if any of the impeller vanes are lightly melted or have cracks in the roots or worn off, it is recommended to replace the impeller.
Signs of a bad boat impeller are either boat engine overheats when you try to accelerate, loss in impeller vanes flexibility, physical wear & tear like cracks in impeller vane roots, melted or worn of vanes. Even if you see less or no water coming out of tell-tale, it might be due to a bad impeller.
Many people will use the two terms (vessel and boat) interchangeably, confusing few people in differentiating between them. In this article, we will walk you through the difference between a vessel.
Tip – If you are thinking of replacing your boat impeller yearly regardless of its condition, keep the old one as a spare in your boat. You can use the old one during an emergency.here
Impeller pumps generally fail in one of two ways. The first is a gradual degradation in pump performance and flow. This is usually due to impeller or housing wear or impeller age. The second failure mode is sudden, catastrophic failure, with the impeller usually loosing some or all of its blades.
Also Know, how long does an impeller last? You should check the impeller's condition during Spring Commissioning and every 200 hours of operation. Correctly installed impellers may last for several years, but you should stick to a schedule of preventative instead of emergency maintenance. more
Besides, how often should an impeller be replaced? more