1969 Johnson 20 hp flywheel won't turn

[Cory_09]

1969 Johnson 20 hp ? not sure of actual model #

Motor last ran a couple of months ago with no problems. Started this weekend and flywheel pin sheared. I replaced the flywheel pin but now the flywheel won?t fully rotate. It will turn about ? rotation and then it stops.

FYI?.
Motor itself is not locked up?.can fully rotate crankshaft with nut. Lower unit is not problem either?.removed lower unit.

Obviously something is preventing the flywheel from turning but I can?t seem to find it. Maybe the pin sheared because the flywheel caught on something??? Any help would be greatly appreciated.

BTW?great resource here. I have read on here numerous times but just now joined.

 

[meyerboy]

Re: 1969 Johnson 20 hp flywheel won't turn

seems a little strange to me, but from everything you negated as the problem, I would think the flywheel is hitting a coil on the stator plate.
I am thinking that the 20 does not have external coils, but if it does, then I would be stumped.

you should be able to see a collision mark on the flywheel or the coil or both if this is the case.

 

[Cory_09]

Re: 1969 Johnson 20 hp flywheel won't turn

I'm stumped as well. No obvious damage on the coils or underside of flywheel. Something caused the flywheel pin to shear, just not sure what.

 

[Chinewalker]

Re: 1969 Johnson 20 hp flywheel won't turn

Is there a piece of the old flywheel key lodged somewhere? Stuck to a magnet? Wedged between the coil and plate? That would explain the partial turning over...

 

[lindy46]

Re: 1969 Johnson 20 hp flywheel won't turn

Are you sure a coil hasn't loosened up?

 

[1946Zephyr]

Re: 1969 Johnson 20 hp flywheel won't turn

Chinewalker makes perfect sense. I would pull the flywheel and check for any fragments lying around in there and make sure none are stuck to the flywheel. While you're in there, make sure that the coils are perfectly lined up to the machined surfaces on the mag plate. Also check and make sure all the screws are tight.

 

[Cory_09]

Re: 1969 Johnson 20 hp flywheel won't turn

Thanks for the help so far. I don't think it's a piece of the old flywheel key as I retrieved the broken key pieces still lodged in the flywheel and cam....at least I think I got everything. I did remove one of the coils so maybe I didn't get it seated back down correctly. I will check tonight. Thanks again guys. This is a great resource!

 

[wilde1j]

Re: 1969 Johnson 20 hp flywheel won't turn

Flywheel MUST be torqued to the correct value or you will keep shearing keys. You get a few tries to get it right before you destroy the flywheel and C/S. Each failed time, the damage gets worse. Bore and taper must be clean and dry (no oil or other substances).

 

[boobie]

Re: 1969 Johnson 20 hp flywheel won't turn

How many times have you rotated the p/h over with just the flywheel nut on and the plugs out ?

 

[Cory_09]

Re: 1969 Johnson 20 hp flywheel won't turn

Checked everything again tonight and just as you guys suggested the coil wasn't lined up correctly and was preventing full rotation. I don't have spark on one plug but I think the points were bumped while I was working on it. I plan on adjusting the points tomorrow. Any suggestions on flywheel torque and point gap? 105 lbs and .20?? Thanks for all the help.

 

[kfa4303]

Re: 1969 Johnson 20 hp flywheel won't turn

yeah, you gotta make sure the coil faces are perfectly flush with the boss on the magneto plate. hopefully, no major damage was done. once you've corrected the problem, turn the flywheel CLOCKWISE a few times by hand. If it's ok by hand you're probably ok to tighten down the flywheel nut fully. I believe 105-115 ft./lb is ok, but BEFORE you put the flywheel back on for good, the points must be set at .020 NOT .20. Make sure the points are nice and clean too. new would be best. make sure that the gap on each set of points is set while the cam lobe is at it highest position. you want the arm on the points to be on the TOP stamped into the cam, then rotate 180 degrees and repeat for second set of points. you can check for a very crude spark by spinning the flywheel by hand with spark plugs grounded on the engine body. It's not a proper test, but it's a good rough way to check and see if you're getting some spark before you put everything back together. if you do see/hear a bright, blue spark, then you can do a proper spark test with a gap tester. spark should jump a 7/16" gap. good luck. keep us posted.

 

[samo_ott]

Re: 1969 Johnson 20 hp flywheel won't turn

I think the torque is 50-55 lbs but I don't have my book with me. Someone else will chip in I'm sure.

 

[kfa4303]

Re: 1969 Johnson 20 hp flywheel won't turn

Hey Cory. Samo is right about the flywheel torque spec. Should be about 50 ft/lbs. Here's a link to the same questions here at the forums. It's for a '69 20 hp, but should be close. F R says 40-45 and he is never wrong Split the difference with Samo and go with 45 ft/lbs and you should be good. Good luck.

http://forums.iboats.com/showthread.php?t=346517

 

[samo_ott]

Re: 1969 Johnson 20 hp flywheel won't turn

Just looked it up. 480-540 in lbs. Which is 40-45 ft lbs.

 

[Cory_09]

Re: 1969 Johnson 20 hp flywheel won't turn

Ok.....I reset the points tonight and now have spark on both plugs. I did not check the actual spark gap but rather just checked with the plugs against the block. However, the motor won't start. I'm pretty sure it's not a fuel issue as the carb was cleaned and rebuilt recently and used several times after the rebuild with no problems. Additionally, the motor started and idled a couple of days ago prior to the flywheel key shearing.


Is it possible that I have spark but not enough to actually fire the motor?

 

[1946Zephyr]

Re: 1969 Johnson 20 hp flywheel won't turn

The points need to be gapped correctly

 

[kbait]

Re: 1969 Johnson 20 hp flywheel won't turn

I've heard that you can check the gap in 'air' with using an old spark plug, and opening the gap to 1/4" and checking against block. If you're getting that, it should spark enough to run. If it still doesn't run, squirt a bit of pre-mix in the plug holes and try again. If it runs momentarily, you have a fuel delivery issue.
Good luck!

 

[kfa4303]

Re: 1969 Johnson 20 hp flywheel won't turn

Hi Cory. You're right. You may have some spark, but not necessarily enough. the s'plug on the engine block test is crude at best. kbait is right about taking an old s'plug and straitening out the prong to 1/4". test the plug on each s'plug wire one at the time. if you get a good spark, you're probably ok. i would also try removing the s'plugs, spraying a bit of carb cleaner, starter fluid or pre mix in each cylinder, then trying to start her again. keep the faith. she was running a few days ago, so you'll get her running. keep us posted.

 

[Cory_09]

Re: 1969 Johnson 20 hp flywheel won't turn

Just wanted to say thanks for all the input. She's fixed now!

 

[kfa4303]

Re: 1969 Johnson 20 hp flywheel won't turn

what was the fix? how did you get her running again? glad she's running, now go fishin'