Impeller replacement schedule

[davidmbv]

Hello, curious if anyone can suggest how often to replace the impeller on early 70’s 25hp Johnson(OMC). I’m currently maintaining several of these outboards for my personal use on my fishing boat. I’m guessing it depends on how many hours I run them etc. I typically run them a few hours a month during the spring and summer. Not sure if this is something I should replace every few years or…?
Thanks

 

[Crosbyman]

all depends on hours/year of use & the quality of the impeller

I have seen some lasting 10 years + but to be safe 5 years sounds a good mid point. Some swear by 3 years . This should be an interesting thread.....

 

[Scott Danforth]

Hello, curious if anyone can suggest how often to replace the impeller on early 70’s 25hp Johnson(OMC). I’m currently maintaining several of these outboards for my personal use on my fishing boat. I’m guessing it depends on how many hours I run them etc. I typically run them a few hours a month during the spring and summer. Not sure if this is something I should replace every few years or…?
Thanks

the rubber doesnt care if you use the motor or not. it goes on calendar time or hours, which ever occurs first. usually its calendar time

for example 3 years or 200 hours

 

[racerone]

If I was running one of those it would be every 5 years.----But you should remove the lower unit to inspect / replace o-ring at top of driveshaft.-----Grease the splines.-----All very simple work.

 

[saltchuckmatt]

I had one last 25 years but it was on a small outboard (8hp)
I change mine about every 7 years but I monitor it closely and I do inspect it and lube the shaft more than that.

How you use it and where you run it is also a factor.

 

[JimS123]

I know I'll get flak, but I'll go ahead anyway.

Our vacation boat had a 1970 9.5 Evinrude and I replaced the impeller in 1986 when I bought the boat. I took the motor out of routine service in 2009 and it still was pumping well. Only a few trips since then and all was still good.

My 1984 Evinrude 9.9 was bought new and the impeller was changed in 2019. It was still pumping well, but when I took it out I could see that I should have done it sooner.

All my usage is in fresh clean water, if that makes any difference, and off season the engines are stored indoors. I admit to being a procrastinator, and I don't advise waiting so long. Nevertheless, it seems to me that impeller changes are not as critical as some say.

 

[Crosbyman]

Dry runs in the driveway probably kill more impellers than years of looking for fish.

my 75 ETEC probably has had 3 impellers in 17 years and all looked fine when replaced... did them anyway to be safe

.an ounce of prevention is worth a pound of cure

 

[racerone]

You have to realize that these smaller motors do not have an overheat alarm.-----They do not have a shutdown system.------They keep running till major damage occurs.-----A wise person would install a new one every 5 years.

 

[davidmbv]

Perfect. Thanks for all the feedback. I’ll plan to pull the lower unit and check o-ring etc every few years and might as well error on the side of caution and replace the impeller while I’m at it unless it looks new. I’m thinking every 3 years can’t hurt . Thanks again

 

[roscoe]

It may look new, but replace it anyway.
They always look new, until they don't.

Run your motor through a bunch of sand and the impeller may only last a few hours.

 

[909]

Buy OEM

 

[RBoyd1971]

I think the deal is the rubber these days. It doesn't last nearly as long as it used to. Stick to OEM or US aftermarket. If you buy Chinese rubber products, it'll last about a year or less. I've had motors 20 years old with functional impellers. Now days you better check them at least every 5 years and stear clear of the cheap Chinese Amazon and eBay stuff.

 

[Crosbyman]

Agree... some stuff is cheap but....I can't say that I have yet to read that many horror stories of impeller causing catastrophic damages, after reading thousands.... posts from 3-4 sites across 20 years . But I agree yes...horror stories do happen ...from neglect more likely.

Seen much more complaints on cheap carb kits, melting gaskets and fuel pumps.

Yes some fins have broken off and clogged passages and some of the center cores got loose but across how many millions of impellers including Amazon, Wally mart Ebay stuff ?

Gross neglect incl. oiling gear cases, flushing salty engines, simple waxing and paint touch ups not to mention changing anodes probably causes much more failures. Did I mention poor maintenance of electricals and making sure the brother in law will add some oil in the fuel on a borrowed kicker ?

Maintenance and boating go together ,,,some folks just pull ropes or turn keys expecting stuff to work . Certainly OB mechanics see more horror stories but what is ratio to long time running engines going back 50-70 years + with just simple TLC ?