'58 RDS-20 35 hp New Problem

[CATransplant]

I replaced the impeller on this motor, added new plugs, and ran it in a barrel a couple of times before putting it on the lake, which I did yesterday.<br /><br />After I launched, it started a couple of times, then died and wouldn't restart. I got back to the ramp with my 5 hp kicker.<br /><br />Back home, I put it back in the barrel. No spark at all, from either plug. Previously, it had nice big fat sparks when tested...on both cylinders. Compression on both is 105. Carb is working fine. The reason it won't start is that there's no spark, and that's my question.<br /><br />I considered a wiring problem, and disconnected all the wires from the magneto to the external junction box and from the vaccuum cutout and mercury switches, just to make sure one of those wasn't the culprit. I also tracked the wires as far as I could and there's no short in the magneto wires. I unplugged the external connection, too, and did the next spark tests with the rope. Still no spark on either wire. What happened here. It seems wierd that I'd suddenly lose spark on both cylinders when it had run fine before.<br /><br />So...is there anything else I can check on this motor before pulling the flywheel and replacing the points and coils (I have both coming)?<br /><br />I was just surprised, because it ran so well in the barrel, then died a sudden death on the lake, even before it ran long enough to get going.<br /><br />All ideas gratefully received. I want to keep this outboard, since it goes well with the age of the boat, but I don't want to pour huge amounts of money into it.

 

[Paul Moir]

Re: '58 RDS-20 35 hp New Problem

I think it's almost definitely a sheared flywheel key. Hardly anything else will cause you to loose spark on both cyls at the same time. If the nut wasn't torqued to precisely 105ft/lbs or the mating surfaces weren't in good shape, this will happen. All it takes is one good sneeze.<br />Pull the flywheel and you'll know for certain. Post back with what you find.

 

[CATransplant]

Re: '58 RDS-20 35 hp New Problem

I'll do that. Will my local OMC dealer have the key for this old engine, or should I order one on the 'net today?

 

[Paul Moir]

Re: '58 RDS-20 35 hp New Problem

He ought to have them. They're often needed and they were used on a variety of outboards. Besides, it's always best to be certain of the problem before shopping for parts. Who knows - maybe the top crank seal blew out for some reason and the points are dripping with fuel/oil?

 

[CATransplant]

Re: '58 RDS-20 35 hp New Problem

Well, it's such a cheap part, I'd rather have it on hand when I pull the flywheel. If, OTOH, this engine has blown its upper seal...it's going to Twin Cities Outboard as partial payment for another engine. I've run out of patience. I'll pull the flywheel and even put new points and coils in it, since I have them on hand, but If the thing's worn enough to need a new seal, it's going to be beads for that engine.<br /><br />I like keeping old engines on the water, but there comes a point past which I won't go. Replace that seal, then what's the next thing to go south?<br /><br />The thing's almost 50 years old now. If it ends up being a good runner, I might get a season or two out of it before I retire it. If not, it goes to Twin Cities as a parts donor and I get a motor that's only 30 years old or something like that.<br /><br />Parts are getting scarce for these old big twins, it seems, especially when you get into powerhead internals.<br /><br />But, I checked the part number for that key, and my local OMC dealer has one on hand, so I'll go ahead and spend the $3 for it.<br /><br />Thanks for your help.

 

[Paul Moir]

Re: '58 RDS-20 35 hp New Problem

It's probably the key, I was just making a point.<br /><br />Ah, things arn't that bad for parts. Top seal for example you can get at any bearing shop for a $ or two. Even internals aren't bad. Bearings and such are easily enough found. Heck, I've been keeping an eye out for parts for a '65 33hp (pretty much the same as your 35hp) that I plan to rebuild down the road. Since January I've already got a NOS +020 over piston and a couple sets of +020 rings for it, and I'm not actively looking for parts just taking ebay specials that have come across. Compared to someone who's stuck with a Force or older Yamaha or such, we've got it easy. Even other J/E owners have it worse - price up a set of points for an early '70s triple for example.<br /><br />Why give up now just when it's getting fun?

 

[CATransplant]

Re: '58 RDS-20 35 hp New Problem

Well, Paul Moir was right, as usual. I pulled the flywheel on this old Super Seahorse and, sure enough, the woodruff key was sheared right off. Apparently, the last person who worked on it didn't torque the nut correctly. It was way too easy to loosen, so that's why.<br /><br />When the key got sheared, it smeared part of itself against the keyway, so what was left of the key wouldn't come out, even with light taps of a punch.<br /><br />I ended up having to use a Dremel tool with a cutoff wheel to grind a groove down the center of the key. I then undercut the groove toward the edges of the key. Once that was done, the presure on the key was relieved and it popped out.<br /><br />The coils and points were brand new, by appearances, and there was no evidence of leaking on the crankshaft seal. I reset the gap on the points, then replaced the flywheel, torquing it to 105 lb. Back on with the recoil starter, chasing small parts a couple of time.<br /><br />Hooked up the battery and gas, a little choke, and this 48-year-old Johnson fired right up. Now it's back to the lake tomorrow or Monday for another on-the-water test.<br /><br />Thanks to Paul for leading me in this direction. I would not have thought of the sheared key, and that was his first diagnosis after my description of what happened.<br /><br />This is a TERRIFIC site, and no thanks is enough for the folks who give of their time to help people keep their outboards running.

 

[cajun555]

Re: '58 RDS-20 35 hp New Problem

When putting the flywheel back on check the condition of crank and hole in f/w. You might want to use a small amount of valve lapping coumpound to dress up both pieces. Don't get carried away with the stuff. Also don't use any grease or oils when reassembling flywheel to crank and torqe down the nut to what Paul says.

 

[CATransplant]

Re: '58 RDS-20 35 hp New Problem

Thanks for the advice, cajun55. I did all that, based on other threads here on the forum. I think everything's in good shape, now. I just wish the previous owner had been reading this forum when he installed the new points and coils. He didn't torque the flywheel nut properly, which is why I was dead in the water.<br /><br />Again, this site is dynamite!