Johnson 6R-72D Maintenance

[mrlatj]

I was given my grandfathers johnson 6-hp seahorse and want to do routine maintenance before firing it up. It has not been run for at least 5 years. My folks are looking for the manual, but at this point I have no documentation. Does anyone have suggestions for what should be checked? What kind of gear oil goes in the lower unit? Any help would be greatly appreciated.

TJ

 

[nwcove]

Re: Johnson 6R-72D Maintenance

check the top secret file at the beginning of this forum. tons of info on awakening an old ob. compression test should be first up, just to make sure its worth spending money on tho....do that and post back with numbers. welcome to iboats!!

 

[tx1961whaler]

Re: Johnson 6R-72D Maintenance

Yes, read the thread here: http://forums.iboats.com/showthread.php?t=158086

Here's my short list:
Take the spark plugs out and spray (squirt bottle) some 50:1 gas/oil mix in the cylinders.
See make sure you can rotate the flywheel easily be hand (clockwise).
If it rotates easily, then check the compression using a compression tester. That motor 65-85psi while pull starting would be OK as long as it is even between the cylinders. If it does not rotate easily, then don't force it. Spray some penetrating oil in the cylinders and let it stew for a day and try again.
If the compression checks out, then use a spark tester to see if each coil puts out enough to jump a 1/4" gap. If there is not spark on both cylinders then you'll have to pull the flywheel.
If you do have both spark and compression, then try to start it in a barrel or trashcan with fresh gas, 50:1 mix.

If it starts, then you're not quite done. If you don't absolutely know how old the water pump impeller is, change it.
Change the gear lube (85-90W marine gear oil). DON'T TAKE OUT THE PHILLIPS HEAD SCREW!
Change out the nylon washers on the vent and fill screws while you're at it. Check the gear oil after the first run to see if water leaks in.

 

[F_R]

Re: Johnson 6R-72D Maintenance

The owner's manual is what you need for operation and maintenance. You can get a copy at www.outboardbooks.com They also have the service and parts manuals, which are for repairs beyond everyday maintenance.

 

[mrlatj]

Re: Johnson 6R-72D Maintenance

Thanks for the info. I will have to look for a compression guage. I drained the gas tank and put in a fresh gallon of gas with half a can of sea foam and fresh 2-cycle mixed a little heavier than 50:1. I set up the ob in a bucket and it fired on the 3rd pull. Should the water pump work at idle? I did not see any water pumping out of where I thought it should be, but it has been many years since I saw this ob in operation. I put in forward just for a moment, but that caused so much turbulence in the bucket that it may not have been able to draw water in. The lower unit oil is drained and refilled so I guess the water pump / impeller is next. Are there any tricks to getting at the water pump to check the impeller? Thanks for any pointers you can provide.

Tj

 

[mrlatj]

Re: Johnson 6R-72D Maintenance

Thanks for your help. I also got some advise on another thread for getting the lower unit off. The water pump is cleaned out, the impeller looked surprisingly good and all is reassembled and running.

 

[nwcove]

Re: Johnson 6R-72D Maintenance

you did install a new impeller??...right??