changing impeler

royal50

Seaman Apprentice
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Jun 22, 2009
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So I decided to change out my impeler on my 94 force 120 and when i removed the lower unit and I was dropping it down the seal that is above the long shaft came down as well. After having such a hard time to put it back up there because of the space, my neighbor told me that the seal should of have been covered by some sort of plastic cover. It's that correct? I own the boat for years now and I changed the impeler before and I always had to put the seal back up there because it always fell. Please help.
 

jerryjerry05

Supreme Mariner
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May 7, 2008
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Your link to the tiny pic only goes to the site.
We need a word to open the pic??
The seal is it rubber,about an inch long and has a metal collar?
 

royal50

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Jun 22, 2009
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Jerry, yes the seal looks just like that. For some reason my picture file is too large so I'm trying to repost another one.
 

royal50

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Jun 22, 2009
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Frank Acampora

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Jan 19, 2007
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Wrong! The black thing you see in the second photo IS a seal for the lower crankshaft bearing. The piece that drops out is a seal to try and keep water or condensation out of the crankshaft splines. The drive shaft is stainless but the crankshaft is hardened steel. If water gets into the splines the crank will rust and cold weld the drive shaft into it. To help prevent this, each time you remove the lower unit coat the drive shaft splines with a light coating of anti-seize or high quality marine grease. I don.t remember dropping a Mercury lower unit, but older US Marine drive shafts had a collar on top to locate the rubber bellows seal.
 

royal50

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Jun 22, 2009
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Frank thanks for your reply. So I will make sure to grease the splines. But am I missing some sort of cover or is that seal supposed to be exposed like shown on my pics? Thanks. Below is a pic of the upper part of the drive shaft showing the rubber boot.
 

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Frank Acampora

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The photo is correct and the boot is in the correct position. Do not use a lot of grease. do not gop it on. To do so can cause hydraulic pressure, pre-loading the drive shaft. Just wipe on a bit and rub it into the splines with your finger.
 

royal50

Seaman Apprentice
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Jun 22, 2009
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49
So I'm good putting everything back as is? And not worry about the seal up inside the top?
 

royal50

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Jun 22, 2009
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Man you have no idea how that makes me feel right now. I thought my motor was done.
 

royal50

Seaman Apprentice
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Jun 22, 2009
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49
So how do I know which direction to put the new impeler back on? I want to make sure that I'm doing this correct.
 

Frank Acampora

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Jan 19, 2007
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Simple. You slide the impeller down the drive shaft and over the drive key with either side up. Then you squirt some soapy water onto the impeller and into the pump body. Slide the pump body down the drive shaft until it contacts the impeller. THEN, while pushing down on the pump turn the drive shaft in a clockwise direction by hand until the impeller enters the pump. Clockwise is looking down at the pump.

Bolt everything together and you are good to go. Do not get medieval on the pump nuts. It is made of plastic and overtightening can harm it. The nuts are self locking and snugged down tightly will do,
 

jerryjerry05

Supreme Mariner
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May 7, 2008
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The impeller can't be installed wrong.
The blades will orient themselves when the motors turned over.
But DO put some lube on the vanes.
I use grease.Soaps good too.
 

royal50

Seaman Apprentice
Joined
Jun 22, 2009
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So I got everything back together and I ran the motor for a little bit just to make sure it sounded ok. My question is, how much should the motor pee water while the ear muffs are on? I don't usually see any water come out from the two holes. Sorry about my lack of knowledge and using wrong part names here.
I only really see the motor pee when we are out on the water.
 

Nordin

Commander
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Jun 12, 2010
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2,428
Depending how tight the muffs are at the gearhouse. If it is not enough the pee will show nothing.

Most of the water will enter through the exhaust (propcenter) but some water would pee too.
The peeholes are actually an idling relief and will work when the engine is in water.
 

royal50

Seaman Apprentice
Joined
Jun 22, 2009
Messages
49
I could see how my muffs may be the issue. Water usually leaks all around. I guess I can't get a tight fit. I will see how it does out on the water.
 

jerryjerry05

Supreme Mariner
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May 7, 2008
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The 94 's exhaust doesn't come through the prop.
The water/ exhaust comes through the snout.
That didn't happen until 95.
The 2 holes are for excess water. You might not see any water there.
Not sure if the installed a pee tube or not but put one in.
If you don't see a lot of water, duct tape the muffs in place.Needs to be dry.

Test the overheat system.
 
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