1956 Johnson RD-18 nearing completion...

[gjonz]

Well, many moons ago I wrote of the saga of my purchasing a 1956 Johnson Javelin and a 1956 RD 18 parts motor.

Turns out the RD-18 was not seized as was believed. Rather it was the better of the two motors.

Well I tore it apart, rebuilt it with all new bearing, seals, gaskets, pistons,etc. Tonight I am relieved that I tried the compression test and tweeked the ignition.

I'm thrilled to report...IT'S ALIVE!

Well almost. I can't test it until the weather clears.

I got a blue spark...very strong over a 1/2 or 3/4 inch gap on both cylinders. Ths compression is at 95psi on the lower cylinder, and 92 on the top. I think this is great since I had the cylinders honed, and the rings haven't seated yet.

My lower unit had to go back to the paint shop for touch up after assembly, but this will look like a million bucks after it's finished.

I guess I'm just excited because this is the first motor I have ever...I mean EVER worked on.

The folks on this forum are largely responsible from my education and ability to complete this project.

Thanks to all of you in the community!

Greg Jones

 

[wbeaton]

Re: 1956 Johnson RD-18 nearing completion...

So glad to hear its coming along. I can't wait to see some photos.

 

[coolguy147]

Re: 1956 Johnson RD-18 nearing completion...

so the one with 95 pounts average in the cylinders is the one u rebuild?

lol wow u know my motor has 95 pounds dead even in both cylinders and im pretty sure its a welll used motor but and i never even touched the power head before

 

[wbeaton]

Re: 1956 Johnson RD-18 nearing completion...

so the one with 95 pounts average in the cylinders is the one u rebuild?

lol wow u know my motor has 95 pounds dead even in both cylinders and im pretty sure its a welll used motor but and i never even touched the power head before

He would have replaced the rings in both cylinders, coolguy. The compression should come up once the motor is broke in and the rings are seated.

I just rebuilt a 1973 Johnson 2 hp single. That little bugger has 110lbs and I haven't even fired it up, yet. Poor little guy, its previous owner tore it apart thinking its problem was compression. Turned out it just had a bad coil. C'est la vie.

 

[gjonz]

Re: 1956 Johnson RD-18 nearing completion...

Thanks wbeaton for pointing that out. I wasn't sure what coolguy was getting at there.

I expect the compression will rise significantly when she's broken in.

This motor was said to be seized up, but in fact the recoil pawls had grabbed the inspection cover on the flywheel. It was free as soon as I removed the recoil. But the guy I got it from said it was scrap.

Boy won't he be surprised!?!?

Greg

 

[patman123]

Re: 1956 Johnson RD-18 nearing completion...

Hi, i have twin 1956 johnson javelins and was wondering if you know where to get parts for these?

thanks

 

[thbtgold]

Re: 1956 Johnson RD-18 nearing completion...

where did you get parts for 18 hp johnson? I just picked up a 1959 FD13 model motor and I want to rebuild the powerhead this winter. Thanks, Tom

RE: Disreguard this post. I found all the info I need.

 

[Shizzy]

Re: 1956 Johnson RD-18 nearing completion...

cant wait to see pics

 

[thbtgold]

Re: 1956 Johnson RD-18 nearing completion...

Do you recall which way the lower crankshaft thrust washer faced? It has grooves on one side.

 

[tmcalavy]

Re: 1956 Johnson RD-18 nearing completion...

Parts from Laings, Twin City Outboards, Engine/Blade & Prop...all on the web.