# Impeller problems



## hferrell87 (Jan 28, 2013)

hrparkg20 said:


> Hey guys, I just replaced the impeller on my 2006 Tohatsu 9.8 4 stroke because it was starting to pee really weak. After installation of the new impeller, the motor no longer pees at all. I know that this is most likely my fault as this was my first attempt at this.
> 
> Has this happened to anyone else? What fixed it?


Sounds like you may have the impeller blades turned the wrong direction . Drop the lower unit again and make sure the blades of the impeller are all curved the correct way. You can take a light amount of marine grease and lube the inside of the cartridge (metal bowl that the impeller spins within) and makes it easier to get the blades to turn the direction you want.


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## yobata (Jul 14, 2015)

also make sure that the tube on top of the cartridge that leads the water up to the powerhead seals back up properly... Another problem which can happen is if the old impeller was dry rotted a small piece of it could become lodged and block the flow of water in the tubing...


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## hferrell87 (Jan 28, 2013)

Agreed, but if it was pissing prior to servicing the impeller, a blockage probably isn't the problem. hrparkg20, what did the impeller look like when you took it out? What about the housing?


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## ADicus (Feb 15, 2013)

More than likely the blades not all the same direction. If your going to lube it use some cooking oil vs grease it will dissipate faster than grease and not catch debris causing more problems either will work not downing someone suggestion just what i've learned the hard way. Good luck


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## hrparkg20 (Apr 7, 2015)

The motor was pissing lightly before I put the new impeller in, so I don't think its a blockage issue. 

To be honest I didn't know that the blade direction was a big deal and didn't note which direction the blades were on the old impeller. I just figured the blades would sit properly once I started the motor. (Last time I assume that)

So that seems to be the problem. I will pull the lower unit off again and switch the blade direction and hopefully that will help!

Thanks for all the input guys. I'll let you know if I still have problems after the blade direction switch.


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## hferrell87 (Jan 28, 2013)

hrparkg20 said:


> The motor was pissing lightly before I put the new impeller in, so I don't think its a blockage issue.
> 
> To be honest I didn't know that the blade direction was a big deal and didn't note which direction the blades were on the old impeller. I just figured the blades would sit properly once I started the motor. (Last time I assume that)
> 
> ...


Good luck and hopefully that fixes the problem...!


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## DuckNut (Apr 3, 2009)

The blades need to be in a right hand rotation. When you put the metal bowl back on twist it counter clockwise while pushing down.


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## noeettica (Sep 23, 2007)

Like this except upside down 

http://www.customgheenoe.com/forum/viewtopic.php?f=5&t=28211


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## hrparkg20 (Apr 7, 2015)

Hey guys, I just wanted to give an update:

I switched the direction of the blades and now the motor is pissing strong.

Thanks for all the help!


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## hferrell87 (Jan 28, 2013)

hrparkg20 said:


> Hey guys, I just wanted to give an update:
> 
> I switched the direction of the blades and now the motor is pissing strong.
> 
> Thanks for all the help!


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## stumpy164 (May 8, 2016)

hferrell87 said:


> Sounds like you may have the impeller blades turned the wrong direction . Drop the lower unit again and make sure the blades of the impeller are all curved the correct way. You can take a light amount of marine grease and lube the inside of the cartridge (metal bowl that the impeller spins within) and makes it easier to get the blades to turn the direction you want.



direction impeller is installed,that isn't a factor - meaning,which way the vanes are bent

impeller goes down one way - the rotation of the shaft,it allows the vanes to fall into the correct position

impellers are "bi directional"

what's important is the gasket surfaces - gasket surfaces that are compromised,these will cause the motor to suck air @ the waterpump...

tell tale streams are often clogged from debris - a small paperclip,pushed into the tell tale clears it

the amount of water from the tell tale isn't the best indicator of a bad water pump


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## DuckNut (Apr 3, 2009)

Stumpy,
Your statement about the direction of the blades is not true. If a blade is bent the wrong way you will not pick up water. If all blades are the wrong way you will not pick up water.

The blades are stiff enough that the rotation of the shaft will not "right" the blade if it is bent the wrong way, it will simply be bent the wrong direction and cause cavitation and not pick up water.


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## stumpy164 (May 8, 2016)

DuckNut said:


> Stumpy,
> Your statement about the direction of the blades is not true. If a blade is bent the wrong way you will not pick up water. If all blades are the wrong way you will not pick up water.
> 
> The blades are stiff enough that the rotation of the shaft will not "right" the blade if it is bent the wrong way, it will simply be bent the wrong direction and cause cavitation and not pick up water.



I assure you,i have quite a few years experience,and i'm a certified marine tech - I promise you,the statement you made is indeed incorrect

the below statement refers to outboard water pump impellers:

impellers are cut for the key,most,not all impellers can only go on the shaft one way.the rotation of that impeller will "right" itself,as soon as the shaft rotates - stating the impeller is in "backwards",is an old wive's tale

"cavitation" - that's when the water pump sucks air. an example of this is,if the sealing surface,where the pump mounts down is compromised - it's not sealing.the pump will "pull" water,when the boat is NOT on plane - when the boat's on plane,the cavitation plates are above the water line,the point where the lower unit mounts to the midsection is also above the waterline - the water pump will "suck air" at this point in time,if that sealing surface isn't good - that sir,is how a water pump cavitates.it's a common thing.motors will overheat when the boat's on plane,but the water pump is putting out fine,when it's not on plane.


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## DuckNut (Apr 3, 2009)

I promise you that it 100% matters if the blades are the right direction. I have had to fix this issue myself. Also, if you read the post on the fix...he corrected it in this manner. There are also several other members who fixed this exact issue.

Cavitation is not necessarily sucking air. Cavitation is the creation of air space within a solid body or liquid. Your motors propeller can cavitate and it is not sucking air, it created air space in the water from the negative pressure on the backside of the prop and the positive pressure on the face of the prop. This is known as Bernoulli's Law.

I am not a marine tech, but I did stay in a Holiday Inn last night.


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## stumpy164 (May 8, 2016)

DuckNut said:


> I promise you that it 100% matters if the blades are the right direction. I have had to fix this issue myself. Also, if you read the post on the fix...he corrected it in this manner. There are also several other members who fixed this exact issue.
> 
> Cavitation is not necessarily sucking air. Cavitation is the creation of air space within a solid body or liquid. Your motors propeller can cavitate and it is not sucking air, it created air space in the water from the negative pressure on the backside of the prop and the positive pressure on the face of the prop. This is known as Bernoulli's Law.
> 
> I am not a marine tech, but I did stay in a Holiday Inn last night.



I have approx 5 water pumps to replace this coming week - i'll make a videwith my go pro,to prove the point.in order to have "air space" - there first needs to be air...real world experience sir - something that can not be beat.there's "theory" and then there's "practical"


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## permitchaser (Aug 26, 2013)

We're wating


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## Creek Runner (Sep 1, 2011)

Never on much any more and comment even less. But if you installed the impeller with the blades in the wrong direction and started the engine. You might as well go buy another impeller and start over. Starting the enigne with the blades facing the wrong direction will cause the impeller to fail prematurely if not instantaneously. 

Oh and I am a certified master marine tech, and no I'm not going to video myself. 

Creek


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## DuckNut (Apr 3, 2009)

Creek Runner said:


> Never on much any more and comment even less. But if you installed the impeller with the blades in the wrong direction and started the engine. You might as well go buy another impeller and start over. Starting the enigne with the blades facing the wrong direction will cause the impeller to fail prematurely if not instantaneously.
> 
> Oh and I am a certified master marine tech, and no I'm not going to video myself.
> 
> Creek


Bingo...now go back to hibernating.


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## DuckNut (Apr 3, 2009)

stumpy164 said:


> I have approx 5 water pumps to replace this coming week - i'll make a videwith my go pro,to prove the point.in order to have "air space" - there first needs to be air...real world experience sir - something that can not be beat.there's "theory" and then there's "practical"


Did you ever get those videos made?


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## hferrell87 (Jan 28, 2013)

Why is this even up for discussion... A problem was presented... An answer was given... The answer worked... Problem solved


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