Issues with 1957 35 Horse RDE-19

[Rick K]

Some background: Picked up a RDE-19 last nite cheap; figured I would tinker with it and see if I could get it go. For $50, I'm not out a lot, and figured it's a great motor to learn on. After I fixed the wiring harness, she fired right up, as the pull start required a team of strong men.<br /><br />The telltale sprayed like a firehose, and after some adjustments to the mixture, she calmed right down and idled nicely for about an hour. Then it quit pumping water, so I shut it down immediately. Pulled the lower unit - impeller shot, etc. No problem, I can fix that.<br /><br />I checked the compression - 80 top, 120 bottom. Rechecked 3 times. BUT - I didn't have it at full throttle when I checked it, as I was unsure as to whether or not I could crank it "in gear" with the lower unit off.<br /><br />I stoped right there, didn't add any oil to the cylinder, etc.<br /><br />Is it worth going any further with this motor? I can do the de-carb routine, and/or pull the head to see what's up, but if the compression is so far out that bad rings are an indication, someone's gonna have a nice parts motor.<br /><br />Any opinions or direction are always appreciated!<br /><br />Thanks<br />Rick

 

[Paul Moir]

Re: Issues with 1957 35 Horse RDE-19

Do the decarb. These motors are "dirty" and the rings get stuck pretty easily. It doesn't matter if the throttle is open or not, that only makes a couple psi change on most 2-strokes. Really soak the top cylinder. Face the outboard carb down, bring the top piston up and add lots of decarb even.<br /><br />If that doesn't help, pull the head ($15 head gasket) and have a look-see. You could also pull one of the bypass covers and poke at the piston rings to see if they're free. Actually, you can get a pretty good look at the bore with one of the bypass covers off. If you're careful, the gasket will survive. Don't try to remove the exhaust cover; that way madness lies.<br /><br />If it's terminal, you might want to keep an eye on ebay. Powerheads for these engines go pretty cheap. You can use a '57 35hp and some 58s, as well as a '62-'64 28hp (30hp) or a '65-'71 33hp. You can run the later engines with 50:1 to boot.<br /><br />If you want to get really into it, pistons and rings are still available I think, or easily found if not.

 

[Rick K]

Re: Issues with 1957 35 Horse RDE-19

Paul,<br /><br />Thanks for the reply. I pulled the bypass cover and poked at the rings with a small plastic punch. They spring in and out and appear to move freely.<br /><br />The cylinder (what I could see of it) appears to be pretty clean and not scored up, etc. <br /><br />I'll do the decarb and soak up that cylinder as you suggested. <br /><br />Of the work I've done on the motor, it appears the nuts/bolts/screws are all pretty lose. The screws on the bypass cover more or less came out by hand. Could this have something to do with the low compression?<br /><br />I'm thinking perhaps a new gasket kit might be in order...<br /><br />Thanks again<br />Rick

 

[Paul Moir]

Re: Issues with 1957 35 Horse RDE-19

It could conceivably be a blown head gasket too, especially if the loose bolts seem to indicate the engine's been fooled with. If all the rings have a uniform "springyness" to them they're likely not stuck, but it's hard to tell if where they're stuck is only on the exhaust side.<br /><br />Since the block is aluminium, the screws are not heavily torqued. The standard torque for OMC engines on 1/4" fasteners is only 70 inch/lbs, or appx. 6 foot/lbs. Comparitively, the fasteners they used were fairly weak. From a table I made up to aid in disassembling engines, the maximum torque that could be applied to the normal 1/4" fastener before they failed was only 150 inch/lbs. It seems to me that's in the range of a Grade 2 fastener.<br />By comparison, the connecting rod bolts (also 1/4") get torqued to about 360 inch/lbs!

 

[Rick K]

Re: Issues with 1957 35 Horse RDE-19

Paul,<br /><br />You mean I actually get to USE that Snap-On inch-pound torque wrench I got off the truck!!!!<br /><br />EXCELLENT!<br /><br />I was going to just tinker around with this motor, becuase I have a brand new 30hp coming. But now, I think I'm gonna really rip into it. It runs good, I want it to run GREAT!<br /><br />I hope my Seloc and Clymer Manuals are all I need...<br /><br />Thanks again <br />Rick

 

[Paul Moir]

Re: Issues with 1957 35 Horse RDE-19

We can fill you in on the rest!<br /><br />The only thing my ft/lb reading wrench gets used for on outboards is the flywheel nut and some con/rod bolts. <br />There's no real special tools necessary for tearing down a Big Twin. You'll need an 5/16" allen driver to remove the centre main bolts, and a 12 point 5/16" socket for the con-rod bolts. You can get the socket from Sears - the only place I know of that carries it. <br />Also useable is a box-end wrench for the con-rod bolts, but that won't work to torque them back on.

 

[Rick K]

Re: Issues with 1957 35 Horse RDE-19

Thanks Paul...