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Discussion Starter · #1 ·
I have a '95 Johnson 25hp outboard that is not pumping water. I have a few questions as this is the first time I have ever replaced an impeller.

I have disassembled the unit and have the impeller out of it. The impeller is fairly hard to turn in the housing and there was rubber dust down in the housing. Based on the pictures would you replace just the impeller or the entire water pump housing (gaskets, o-rings, seals etc.)? I do not see any cracks or damage to the existing housing.

Take a look at the pictures and let me know what you would do if it were yours. The price difference between a new kit and just the impeller isn't too much but I don't want to waste money. Thanks in advance OGF.

Randallbob
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i would always replace the upper housing, bottom wear plate, plate gaskets, and impeller if it wasnt pumping water. the upper housing can look good but be warped. i changed the impeller in my mercruiser. it still overheated at higher rpm's. so i replaced it again and got the same results. tryed everything i could think of. knew a charter caption that was a part time mechanic. asked him for help and he asked if i had changed the upper housing. got the kit changed the upper housing, bottom wear plate, gaskets on wear plate, and impeller put it back together and problem solved.
 

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Do the whole thing. As you said, the cost difference is negligible but the benefits are worth it. The impeller is hard but the housing is also and the steel plate is worn too as seen in the picture. If the plate is worn you may lose the seal between the bottom or top of the impeller and the pump may not work as well or may not work at all at some speeds. And, the lower housing usually has a new seal in it for the upper section of your lower unit. No point in taking a chance. You're already there so do the whole thing.

You know it.
 

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you got it apart so do it all. and think of the money your saving[if you did it half way and the motor got hot and shut down. now junk]
 

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Discussion Starter · #5 ·
Thanks everyone. I'll just replace it all. In the videos I have watched the say to use marine grease when putting things back together. Does it need to be marine grease or will a quality general purpose or even lithium grease work?
 

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i have always used marine grease but a general purpose grease should work just fine. all it really does is make the inside of the housing slick so the impeller is easier to install, and gives it lube when you first start it up.

i am a firm believer that you should never crank a dry motor.
 

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You have received some good advice on replacing everything since you are already in there and applying the grease.
Also while apart, I would shoot compressed air through all small ports and water passages to insure there are no blockages.
You can also take a piece of weedeater cord and run down through 'pee' hole to make sure it's clear.
 

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I have read where some people use dish soap (Dawn) when putting it back together instead of grease.
Have used it before...it's works good.
The good thing about using grease is its a bit more 'tacky' and will hold things like new keyway in place better when installing impellar on shaft.
Heck...have even used Vaseline,lithium and various greases.
I actually like using Vaseline on the inside of the impellar housing as it washes out clean without gumming up when water hits it.
 

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Discussion Starter · #12 ·
I like the compressed air and weed eater idea for additional protection. This is why I love advice of OGF! Hopefully, someday I can pass on a nugget of helpful information to someone.
 

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neever spin an impeller without water,( under power) that one pic looks like the rubber seized snd the shsft wore the hub sideways ?
 

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also remember when you are sliding the impeller cover down the drive shaft over the impeller make sure to turn the drive shaft clockwise only (as you are looking down from the top of the drive shaft... this will start you impeller fins turning in the correct direction.. do not turn back the opposite direction as you run the risk of some of the impeller fins going in one direction and some going the other direction.. you tube impeller installation on your motor,,, there are some great videos on many of these tasks...
 
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