Torque required to spin water pump shaft when replacing Cobra water pump?

[lakelivin]

I'm replacing the outdrive water pump on my '89 4.3L Cobra. Manual says to turn water pump shaft so narrow end is straight down to help in aligning with the impeller when replacing the housing.<br /><br />I've put pieces of hose over some vise grips and tried to turn the impeller shaft, but that bugger don't want to move. Should it be that hard to rotate the impeller shaft or is that an indication of some other possible problem? Don't want to apply too much pressure and break the shaft...<br /><br />I tried to get it aligned by 'clicking' the ignition key, but it's completely random where the shaft ends up and so far straight down hasn't happened. <br /><br />Note: this is on a rebuilt upper drive with less than 20 hours on it. Pulled the pump cause I heard a whining noise from about where it is located and engine heated up very quickly. The metal insert for the casing was kind of bent and impeller showing some rubber sheared off the ends, so figured I'd just put in a new one.

 

[Bondo]

Re: Torque required to spin water pump shaft when replacing Cobra water pump?

I'm No Expert on OMCs,...<br />But, If I'm not mistaken,... You'll need to turn the Engine over to turn that shaft.....<br />I Don't think your vise-grips are going to do it............<br /><br />Turn the motor over By Hand, rather than bumping the starter......

 

[sea wolf]

Re: Torque required to spin water pump shaft when replacing Cobra water pump?

Don't bother. Just put the impeller on the shaft aligning the cutout, then put the cover on. You'll never get the shaft straight down by using the key. It's not neccessary, I don't care what the manuel says. By the way,lube the impeller with some gear lube.

 

[rodbolt]

Re: Torque required to spin water pump shaft when replacing Cobra water pump?

cause your about 1 step away from junking the shaft<br /> most ran a pressed in stub shaft to make the drive shaft long enough. the impeller shaft portion was a press fit in the drive shaft. dont twist it. hopefully you have not damaged anything. it does not matter where the narrow end points as long as you clock the drive portion of the new impeller in the new housing. replace all the pump parts if any are melted. shows signs of a dry run. if you absolutly must point it down use an assistant and a socket on the crank bolt.but the manual reference is just for ease of installation.

 

[lakelivin]

Re: Torque required to spin water pump shaft when replacing Cobra water pump?

Thanks guys. I read Bondos post before either of the other two of you had posted; used a socket to turn the engine by hand and easily got the alignment I wanted.<br /><br />I can see where the other methods would work as well. I put in a whole new pump (lubed the impeller with gear oil), works great.<br /><br />Fortunately I didn't take that last step & junk the shaft! I was following directions from the OEM service manual; since the instructions said to align the shaft, I think they should have also instructed how to do so! Wonder how many other novices like me (but without access to a forum like this one) trashed the shaft trying to turn it directly.

 

[seahorse5]

Re: Torque required to spin water pump shaft when replacing Cobra water pump?

Lakelivin,<br /><br />In the service manual where they said to turn the shaft to align the impeller, was it after they showed how to remove the outdrive from the boat?

 

[Lou C]

Re: Torque required to spin water pump shaft when replacing Cobra water pump?

In my OMC shop manual, the section dealing with the waterpump shows the outdrive removed from the transom shield so you could turn the shaft just by turning the u-joint shaft. When I did mine for the first time I just installed the impeller in the housing with the vanes oriented the way the orignial one was, and then with the impeller lubed, I used a big screwdriver in the slot in the impeller to properly orient the position of the impeller to the stub shaft, then just trial fitted it without the gasket sealer to make sure it lined up right. Easy job!

 

[lakelivin]

Re: Torque required to spin water pump shaft when replacing Cobra water pump?

Originally posted by seahorse:<br /> Lakelivin,<br /><br />In the service manual where they said to turn the shaft to align the impeller, was it after they showed how to remove the outdrive from the boat?

Yep, now that I look back at the OEM manual it's organized such that all of the water pump stuff comes after instructions on pulling the drive and breaking down other parts in the upper unit. Still, since the water pump is something that can be worked on without pulling the drive, I think a sentence about how to do so would have been in order, and probably would have saved a broken shaft or two by other novices.<br /><br />The Clymers manual is organized such that the water pump section is seperate from anything about pulling the drive (and they specifically state that you can service the water pump without pulling the drive). But they have the same instruction about orienting the shaft so that the narrow end is straight down, without any further instrution about how to do so. <br /><br />Thank goodness I found iboats last summer!<br /><br /> Lou C: yeah, dry fitting the impeller to match the shafts orientation before applying the gasket sealant wouldd have been easiest. I'll have to remember that for similar situations.