The impeller plays a crucial role in your boat engine. If you aren’t careful enough, your wonderful day out in the waters can become worse due to a bad impeller. By knowing the symptoms of a bad impeller, you can avoid that. So, what are the symptoms of a bad boat 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.
When the boat’s engine is turned on, it burns the gas and generates heat inside the cylinders. The raw water (lake or outside water) is sent inside the engine block over the power & cylinder heads, absorbing that heat to cool that heat. With a bad impeller, water can’t be pumped inside.
If your boat impeller goes bad, it will not pump the water inside the engine over the cylinder heads to cool the engine, and it overheats the engine. That being said, we will now see the bad boat alternator symptoms in a detailed way.
Before going into the technical essence related to the impeller, take a look at this small video on the impeller working if you aren’t familiar with its working.
What Are The Bad Boat Impeller Symptoms?
Boat Engine Overheats Frequently
Every engine needs to be cooled down by some means. The boat engines are designed to allow the water to flow over the power & cylinder heads, absorbing the heat to cool the engine. If that water flow is interrupted by anything (if the water does not flow inside the engine block), it overheats the engine quickly.
The impeller pumps that water (see the above video on its working to know more). If the impeller is not working properly, it won’t pump the water, heating the engine. So lately, if your boat engine is heating up frequently, the bad impeller might be causing that issue.
Yet if any trash does adhere inside the water-flowing tubes, it could stop the water flow inside the engine block, overheating the engine. So, you need to check the water flowing lines as well before directly replacing the impeller without any other checks if the engine is frequently overheating.
Related post – Why do boat engines need water? Check this article to know more about the impeller’s importance and how it cools the boat engine.
Physical Wear And Tear (Cracks And Vanes Meltdown)
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.
The impeller can’t be repaired like a propeller or any, so you need to buy a new one. You can get a good impeller for your boat under $50, even on Amazon here. Even the corrosion can be a problem inside the impeller hub; inspect the impeller hub simultaneously while changing the impeller and clean it concurrently.
So, by looking at the impeller’s condition, you can decide whether to replace it or not (most of the time). You can only do this if you inspect the impeller frequently, once every month or so. Otherwise, you may not find the issue until your engine overheats (and stops) in the middle of the lake or elsewhere.
Loss In Impeller Vanes Flexibility
Usually, all the vanes on a brand new impeller will be firm and won’t bend unless you apply any force. But after 50 hrs to 100 hrs of use, they start to bend a little and increases further if you go on. But at some point in time, the vanes may lose flexibility, and all the vanes might lean towards one side.
If those bends are significant, it’s time to replace the impeller. The Bent vanes will not vary the pressure inside the impeller’s housing and won’t pump the water, which heats the engine immediately. So, if you see any significant bent vanes on the impeller, it’s time to replace the impeller.
At 50 hrs to 100 hrs, they may look OK, with fewer cracks or no cracks at all. At 300 hrs, they tend to show the origin of cracks at the impeller vane roots at this level of use. At 500 hrs, they may look distinctly cracked, but if you are lucky, sometimes impeller vanes can still be intact and work ok.
No Or Less Water Coming Out Of Telltale
There could be many other reasons why telltale on your engine is not peeing out water, like internal blockages, etc. But one of them is if the water is not pumping properly inside the engine due to a bad impeller, less water will come from the telltale hole.
If the impeller damage is severe, it may not pump the water inside the engine block at all. Then the telltale will not pee at all. So no or less water will come out of telltale if the engine itself is not getting enough water in the first place due to a bad impeller.
When To Replace A Boat Impeller?
A boat impeller needs to be replaced if its vanes are slightly melted or have cracks in the roots, or worn off. Yet, many experts suggest yearly replacement as a general rule regardless of its condition, but you can do it whenever you see any visible loss OR do it yearly for peace of mind.
Many people may advise you to replace it yearly for a piece of mind. But, as always, inspect it annually (recommended – before every season), look for set in the vanes, tiny cracks in the vane roots, flexibility, and replace on condition. If none are there, you can use it for some more time.
Since the impeller plays a crucial role in keeping the boat engine cool all the time, many say to replace it yearly regardless of its condition, so that you need not worry about the engine failure due to overheating in the middle of the lake. It is up to you if it is in good condition, no need to replace it.
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.
It also depends on the number of hours used and above all what kind of water you boat in, i.e., in muddy waters, you can expect the impeller to wear much faster than in freshwaters. Even if the boat engine is dry started frequently for short periods; as a result, it melts down the impeller quickly.
As mentioned earlier, you can change it whenever you see impeller vanes start to meltdown, OR cracks or wear on the impeller. But if you don’t want to take the risk (of engine failure due to overheating in the middle of the lake), you can replace it yearly or follow the manual and replace it after using it for that many hours.
How To Get Most Out Of Your Boat Impeller?
As always, maintenance plays a crucial role in getting most of anything. If the impeller is taken proper care of by following the steps below, you can last one for a long time. However, it also depends on the number of hours used and above all what kind of water you go in.
Remove the impeller before the long-term storage. Since the impeller is off-set to one side inside the housing, it may keep that shape like that if kept undisturbed for long periods. So, it’s a good practice to remove the impeller from the housing before any long-term storage like winter.
Inspect the impeller at least once every month. Inspecting the impeller is crucial, and it’s highly recommended to inspect it at least once a month. Look for set in the vanes, tiny cracks in the vane roots, flexibility, and replace on condition. If anything there, replace it; otherwise, not needed.
Change the impeller as mentioned in the manual. When you buy an impeller, you will get a manual along with it. They will mention how many hours it will last. It is highly recommended to follow that and change the impeller based on that hours to have peace of mind if you are worried about its failure.
Also, when inserting an impeller, be sure to use durable waterproof grease or other lubricating agents suitable for the purpose and approved by the pump manufacturer on the shaft. So that the impeller will be less likely to become seized to the shaft over time and will be more readily removable when the time comes to do so.
Some manufacturers claim that oil-based grease is bad for the rubber or other material of which the impeller is made and suggest using something like dishwashing soap or other proprietary lubricants. Others say that oil-based grease is fine (source). So, look at the manufactures recommendations before applying any grease.
Check this helpful video on how to replace a boat impeller by boats.com and to know what to look for before replacing the impeller.
The Final Thoughts
When the boat’s engine is turned on, it burns the gas and generates heat inside the cylinders. The raw water (lake or outside water) is sent inside the engine block over the power & cylinder heads, absorbing that heat to cool that heat. With a bad impeller, water can’t be pumped inside, overheating the engine.
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.
Since the impeller plays a crucial role in keeping the boat engine cool all the time, many say to replace it yearly regardless of its condition, so that you need not worry about the engine failure due to overheating in the middle of the lake. It is up to you if it is in good condition, no need to replace it.