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Fish Fry Guy

Newby Outboard Question regarding Impellors

6 posts in this topic

I'm not a knowledgible engine guy other than knowing how to rebuild & service a carb (compliments of my good old 84 Oldsmobile, rust in peace). But.... Can you help me with understanding an outboard engine's Impellor. I believe it is what shoots the water out of the engine, pretty much a water pump right, is this correct? It runs water through the lower unit (where the muffs go) and to the engine block for cooling and shoots it out next to the exhaust. I think that is correct. But either way, when should these be changed? My outboard is 13 years old, I bought it used in '06 and didn't know to ask the question. So, I'm assuming my impellor is original. I probably worry too much but I want to be in "the know" when the time comes to service it. Thanks

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You got the basics right. The impeller is a part inside the water pump housing which is located in the lower drive. The impeller is spun by the drive shaft. It picks up water through the inlet and pushes it via a water tube into the engine when it circulates through a water jacket. The stream of water coming out is called a tell tale. Its purpose is a visual letting you know the pump is pumping. Not only does the water cool the engine, it has to cool the exhaust as well. So if you have a thru-hub/prop exhaust that is where the water exits. If you have an older outboard without thur-hub exhaust the it exits out mid way.

When to change the impeller?

At the first sign your tell tale is putting out a weak stream.

So what if this happens while on an extended trip? Best insurance and piece of mind is to replace it before the weak stream. In your case 16 years, I'd replace the impellor soon.

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Thanks Frank! I may just do that, we are taking a trip up to the BWCA in October and would hate to have problems. We usually take my father in law's '07 boat, but w/the 25HP restrictions on many of the lakes up near the BWCA we are taking mine this year.

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I have a plain 16'er w/25 hp rigged just for the BWCA motor routes too. Since I need to bring extra gas I bring an extra tank with hose. Tools, spark plugs, cable ties, spare impeller(old one), lower unit oil, and spare prop. That takes care of most situations when your in a place where break downs can ruin a trip.

Have a fun trip!

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Thanks! Good call on the spare prop too. Unfortunately, I had my prop eaten up a bit today on WBL. I've boated that lake countless hours and finally had a prop hit bottom. Not on or around Ordway's bar. No lower unit damage at all, skag wasn't even scratched, just the prop now with a 1/4 inch bend on one of the prop blades. I still had no trouble getting on plane and overall it runs ok yet with only minimal amount of off balance shaking. Still stinks though and I know up in BWCA with all the rock around those lakes I probably would have had to get a tow back.

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You can send your bent prop in to a prop repair place (Soderbloom's is a good place) and be back in business for cheaper than buying a new prop!

marine_man

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