'56 Johnson 5.5hp impellar removal

I have been slowing bringing back to life an old '56 Johnson 5.5hp after it sat idle for 10 years. I am not familiar with how the intake/exhaust should operate on this motor as my only comparison is with a '78 Mercury 80hp. There is a thumb-sized hole on the rear side of the shaft housing which has been sputtering water whenever I get it started in my test tank. How can I tell normal operation and should I automatically consider replacing the impellar?<br />I am not sure how to access the impellar area although I have had the lower end slightly apart - I can see it, just can't get to it w/o much more disassembly. Do I need to remove the prop gears, etc., to slide the lower end off in order to expose the impellar. I bought a manual but it's explanation is vague at best.<br />Any help appreciated.

Re: '56 Johnson 5.5hp impellar removal

The water pump sounds like it's operating. The hole on the back is the idle relief and you should see water spitting out. There is no tell tale like newer engines. However, if the impeller sat for 10 years it has likely taken a 'set' and is no longer round. An impeller with a set is likely to fly apart on you when really pressed into service.<br /><br />Unfortunetly, it is a lot of work to remove your LU. First you need to remove the lu bolts and rotate the flywheel until it drops a bit. I guess you've done that part already. Next you need to remove the powerhead (engine) in order to disconnect the shift rod from the shift handle. Stay away from stuff below the water pump - that's the wrong track.

Re: '56 Johnson 5.5hp impellar removal

You will need to remove the powerhead on that model in order to replace the impeller -- have to disconnect the shift rod at the base of the powerhead. But it's not so difficult. You can get the impeller in may places, including NAPA. As I recall, there is a gasket under the powerhead, and you should probably replace it if there is one. After the shift rod is disconnected, you can take apart the leg at the point it bolts together up above the ventilation plate. You will then have access to the impeller.

Re: '56 Johnson 5.5hp impellar removal

To Paul M. -<br />What do you mean by LU?<br /><br />Also, where can I find gaskets for the impellar and what kind of info would a Napa parts counter person need to get a new part for me?<br /><br />You guys are really helpful - learning a lot and having a blast, too!

Re: '56 Johnson 5.5hp impellar removal

brook,<br /><br />L/U means "lower unit" or sometimes called "foot".<br /><br />Ask a NAPA counterperson for the "marine" catalog. They may have to order one.

Re: '56 Johnson 5.5hp impellar removal

Thanks, djohns19.<br />LU = lower unit = lower end.

Re: '56 Johnson 5.5hp impellar removal

NAPA part numbers...<br />Waterpump impeller - 18-3001 (OEM #277181)<br />Powerhead base gasket - 18-2894 (I think) but might be 18-2901 - whichever one matches up with the existing gasket. There are pictures in the catalog...<br />- Scott

Re: '56 Johnson 5.5hp impellar removal

Thanks, Scott.<br /><br />Is there a gasket part no for the impeller or would any marine dealer have access to this?

Re: '56 Johnson 5.5hp impellar removal

Hi Broo there is no gasket as such needed for an empeller change, other than the one powerhead base gasket mentioned. You may have to install new rubber gromets on the water pipe though.

Re: '56 Johnson 5.5hp impellar removal

I rechecked the gasket number using my OMC books - the one you want is #18-2894. The other one is for later model 5/5.5/6hp models...<br />- Scott