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Impeller replacement - help / tips 1988 90hp

donaldboyer

Contributing Member
Hello!

1988 Mercury 90hp EPLTO. s/n 0b312461

I want to put a new impeller into this motor. I haven't done this before, but I am fairly certain that I can do this job myself. I have read a bit and watched a few videos on Youtube of guys showing you how to do this.
I just want to be sure I have it right:

Remove Lower Unit
Remove cover, take out old impeller, and remove gasket(s) from on top of lower unit (the new ones come with an impeller "kit"?)
Put new gasket(s) in and put impeller into housing using dish wash liquid for lube. Slide cover and impeller back on shaft lining up the notch/key. Tighten bolts fairly tight but not super tight.

Reinstall Lower unit and test on muffs.

Is this correct?

Is there anything I need to be careful to do/not do during this? Also any tricks/tips?

As for the shift connections, as long as I don't move the shift rod on the lower unit or at the remote, it will all line up when I reassemble OK?

As for testing, if water comes out the pee hole as per old impeller then I can be fairly certain everything is OK?
As testing in Forward and reverse with muffs will make certain gears are all OK?

What direction does the shaft turn (when looking DOWN shaft towards lower unit)? Do I need to make sure impeller "wings" are facing correct way when it spins?

Sorry for all the questions, I just like to be sure of what I'm doing!
 
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Re: Impeller replacement - help / tips

Shaft turns clockwise from above. The "wings" must all face backwards (lagging).

If water comes out the Tell Tale you're okay. SHifting has nothing to do with it.



Jeff
 
Re: Impeller replacement - help / tips

put everthing in neutral, check prop while working to make sure its still in neutral and before reassembly. Put impeller on driveshaft with key, lube, slide housing over top and turn driveshaft cw while pushing down on housing. drink beer
 
Re: Impeller replacement - help / tips

Changing the impellor is a straight forward enough task to do at home with basic tools, go for it. Go slowly when first fitting the impellor to the splines on the driveshaft, if the impellor has a gland seal at the top it is possibly to tear this by being rough.

The workshop manual for my outboard (older than yours) states that you need to coat the impellor wings with general purpose lubricant.

Don't allow any grease to get on top of the driveshaft, it can prevent the lowerleg assembly from sliding all the way home in the powerhead. Grease doesn't compress and sometimes gets trapped preventing the driveshaft travelling the full distance in the socket.

Further to fastjeff's post "shifting has nothing to do with it" - the shaft which passes through the impellor is always driven the same way by the powerhead. The propellor shaft will turn clockwise or anticlockwise depending on which gear is selected (forward/reverse). Even in neutral, with the powerhead running, the driveshaft (passes through impellor) will continue to rotate. If it didn't your engine could overheat simply by being run for too long in neutral.
 
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