Impeller Life Question?

[Jimzee]

This is for the motor guru's on this site.  My engine, 90 hp Merc was purchased in April 2003.  My question is, do I need to change the impeller or should I have changed it already?  Nothing is wrong with the stream coming out the peehole, it's just as strong as day one.  I heard or read somewhere that it should be changed every three to five years.  Am I boating on borrowed time or should I just leave it alone and abide by, if it ain't broke don't fix it.  Thanks yall!  8-)

[burleytog]

Five years, I'd replace it just for peace of mind.  When I did mine last year, it came out looking pretty good.  I have no idea when it was last replaced, but I felt better knowing that a new piece of rubber was in there.

[Low_Budget_Hooker]

EVERY YR!

Lower leg oil change and new impeller.  $10, 5 minutes

[fishingfourfun]

What range in price am I looking at in replacing my impeller at the marina?  9.9 hp.

[Low_Budget_Hooker]

Usually a minimum of 1 hr labor.  It's a 5-10 min job.  Very easy, they would probably tell you how to do it.  

Note- I do mine every yr but it is in saltwater.  It's a preventative maintenance thing.

To give you an idea of what is involved to see if you can handle it, below is the description for changing a 6 HP merc.

"First make sure boat is in neutral. Under the cavitation plate there will be 2 bolts on side and sometimes one in front and possibly one under trim tab if you have one or in area above prop.

Remove these and lower unit should drop down you will then see the water Pump housing.

Before removing clean shaft so you don't damage seal. I would also lube shaft. Remove bolts or nuts from housing and twist and lift. Watch for small key that fits in the flat slot on shaft.

Pull housing and old impeller off and clean inside housing. Use a small amount of WD 40 to lube inside housing.

Replace impeller being sure to line up key on shaft. Now place housing back on and while turning shaft push housing over impeller. Doesn't matter which way you turn it as it will set itself right when you start motor. Install nuts or bolts and carefully re insert shaft into motor housing being careful to line up water tube, and shift linkage.

Don't force anything,it should fit together without any binding. Replace all bolts and nuts then hook to water hose muff and start to make sure you have water coming from telltale hole."

[Al Wolbach]

I fish at least twice a week year round. I change lower unit oil every 3-4 months. This may be overkill, but I don't have lower unit problems.

The water pump I change every spring. About 35 dollars for parts. I do it myself in a couple of hours. If a water pump impeller is left to long it can become dry and brittle. If a piece of it breaks off it can become lodged in and block a cooling port in the powerhead causing overheating problems and potiental for serious problems. That little impeller controls the lifeblood of your engine. I have known outboards to go 10 years without an obvious problem but that is a big gamble. I would not go more than 3 years under any circumstances.

I don't mean to sound to negative, but preventive maintenance is far cheaper, and easier, than corrective maintenance..............Al

[Jimzee]

Thanks guys, sounds like everyone was thinking the same way.  I will get it done before the boat hits the water this year.  I always change my lower unit oil twice a year.  LBH, thanks for the instructions.  That will save me some money.  

[ABC123]

There is no set interval for changing the impeller. The service life of an impeller is determined by many factors. Quality of the impeller, amount of use, conditions the motor sees, etc...

Obviously a quality impeller will last longer.

The amount of use factors into the life of the impeller. Say you buy a boat, and go on 2 week long fishing trips per year, and the rest of the time the boat sits. Odds are, the impeller will start to dry rot, and possibly fail in 2 or 3 years. A motor seeing action weekly or bi-weekly for the whole warm season (length depending on north or south), 5 years is a good time to change it. Heavier use will wear on the impeller, and service life will be greatly reduced. 2-3 years.

Conditions the motor sees. Sand and salt will wear down the impeller, and service life will be greatly reduced. Annual replacement would not be a bad idea in salty or sandy conditions.

Normal freshwater usage should allow for 3-5 years of service life. Adverse conditions will shorten the service life. It is better safe than sorry, but under normal conditions, annually is a little much IMO.

[burleytog]

BTW, if you do not have a service manual for your OB, it would be wise to purchase one before gettin up in them guts.

[Low_Budget_Hooker]

BTW, if you do not have a service manual for your OB, it would be wise to purchase one before gettin up in them guts.

x2- remember, those directions are for a 6hp, just to give you an idea.  Owning the repair manual is a great investment anyway, I would go grab one.

[bassboy1]

NEVER do anything to your outboard without a manual.  Even mechanics that work on these daily use manuals for certain things.  Now, after a few times, it will become pretty much stuck in the back of your head, and you wont need it, but I usually open it up to the right page, and glance at it a few times, even if it is something simple like a water pump rebuild.  

Also, replace the LU oil fill and vent seals after every change.  They are cheap - having a LU crack because water seeped in, and froze is not.  

[Jimzee]

Thanks for all the help guys.  It is greatly appreciated!  

[Sam]

What a timely question.

I am taking my boat to Jerry Cooper in Ashland, VA to have it "winterized" and to have the impeller replaced.

I hit a couple of mud flats this year and the water stream is not what it used to be.

It is better to be on the safe than sorry side of things and having the motor fail while fishing is not something that anyone wants to experience.

So I suggest, like the other guys, you change the impeller.

[detroit1]

I plan on changing mine this year before the season starts. I have a '96 50hp Evinrude (since new) and have had no problems so far. A  little over 500 trips, maybe 500 hrs. usage, and i'll find out how much wear.