Impeller life expectancy?

[eze2bme]

Since everything petroleum based seems to be going up in price, I'm thinking about buying a supply of impellers for my mains (6-71N's with Depco 17935-0001 impellers). How long should the impellers last if stored in the shipping box? I am in fresh water and change the impellers every other year. Thanks.

 

[MikeP]

I would expect them to last for 6-10 years - about the same as the generally accepted age for a tire that is not used - if stored in a cool area (not the engine room). But that's just a guess. I have never seen any real data on such things.

I used to replace impellers annually - now I pull them every winter, plop them into hot water until they regain their normal (as new) shape and store them in a plastic bag over the winter. In spring I inspect them carefully and if they look ok and seem supple/no cracks, I put them back in service. I have a set of spares on the boat for all impellers but don't plan to buy any more until necessary.

 

[SeaEric]

From now on, I want Mike P to winterize and spring commission my boat.

 

[eze2bme]

Thanks Mike. I use my boat year round since I'm in SC and have found that if I change the impellers every two years that none of the vanes break off. If I wait for three years between changes then the vanes begin to break off and I have to dis-assemble some of the "plumbing" to get out the broken pieces ... not fun! Thanks again!

 

[Passages]

I followed Mikes routine and got 3 yrs out of a new impeller. After 3, it got a spritz of Armor All and put in a dated baggie. That became a spare. Next cycle, the oldest impeller got tossed and replaced with the next in line spare.

I never had an impeller go bad using this system.

 

[REBrueckner]

Instead of buying extra impellers and risking them drying out in storage, why not run each impeller longer...

It would be interesting to know how often commercial boats change impellers...like fishing boats that run 8 hours every day.....

Impeller life mustrelate someway to RPM.....a 100 hours at 1,000 RPM is only half the frictional wear and tear of 100 hours at 2,000 RPM...

I was on about a 300 hour change out...or three years.....and left the impellers in the pump over winter and never had an impeller or vane fail doing that.

I did turn over the engines roughly twice during the winter...enough to rotate all moving components around some....

 

[MikeP]

In my opinion (and that's all it is) an impeller (like a tire or a camshaft drive belt) is much better off being run regularly than sitting still for prolonged periods with several vanes crushed up against the cam.

I believe that breaking a vane is far more likely after an impeller has been in position all winter than it is if the boat is run regularly. That's why I take 'em out and "restore" them in hot water. But I will admit this is just my opinion based on my own "logic." It should not be compared to any actual data!

 

[Glory]

I change the my impellers, mains, every 500 hours, The gen every 3000 hours. Never had a problem.

And they look fine at the above removal hours. The main reason impellers fail is they have been run with no or reduced raw water.

JM