Posts Tagged ‘1956 Johnson RD-18 30 Horsepower outboard motor


I promise to get back to the boat…

My restored 1956 Johnson RD-18 powing our Thompson Lake TVT up the Mighty Maumee River.

My restored 1956 Johnson RD-18C powering our Thompson Lake TVT up the Mighty Maumee River.


but in the meantime, I have been dealing obviously with the loss of Bear, bad weather and working two jobs.

Between all the aforementioned items, my 1956 Johnson RD-18 got finished and barrel tested.  It was a learning experience.

On this particular motor, which was deemed scrapped and for parts only by the person who sold it to me, the following items were missing:

1. Air cleaner box

2. Tiller handle

3. Carburetor, carb needles and knobs

Problem mechanically:

1. Motor was supposedly seized

2. Recoil starter broken

3. Scoring in the cylinders and on the pistons.

4. Head gasket leaking

So after a bit of investigation, and removal of the recoil assembly, I found the motor was in fact in fair shape for a 53 year old motor.  The motor was not seized, but the recoil pawls had snagged the sheet metal inspection plate on the flywheel and locked the motor up.  What to do?!?

Here is a motor that was to be used as a donor, but actually was potentially salvageable.

I couldn’t let it go to scrap!  Instead the following was done to the motor:

1. Complete tear down and cleaning.  The exhaust side of the power head block  was completely clogged with carbon from the fuel mix.  This had to be cleaned out with Krud Kutter and a screw driver.

2. New pistons and rings

3. Cylinders honed

4. New bearings on the connecting rods and the crankshaft journal bearings

5. New power-head gaskets throughout, and new head gasket

6. Carb cleaned and rebuilt

7. All fuel lines replaced

8. New points and condensers on the magneto ignition.

9. Hunting down and finding the missing parts and replacing them

10. Update electrical components from 6 volts to 12 volts.

11. Lower unit rebuild and new clutch dog installed

12. All seals replaced in the lower unit and on the crankshaft

13. Electric Start installed with starter and geared flywheel

14. Bead blasted and repainted with new decals

After all this the preliminary test looked good!  The compression was 90 and 92 pound on each cylinder.  Not bad considering the pistons and rings still needed to seat.  A few neighbors helped lug “The Beast” out of the basement to the garage for testing in a 55 gallon “lake”.

Well upon attempting to start the motor, it was clear that the the motor was not going to crank and FIRE.  Why?  Checked the pressure tank which was rebuilt and worked great.  Good spark!  A fuel problem perhaps?

You bet!

I got very frustrated and posted my issues on the Antique Outboard Collectors website and got a swift answer.  The carb rebuild kit has many extra parts due to it being used for many types of carbs.  The directions were next to non-existent.

Very quickly the AMOCI group led me to the fact that the replacement fuel float needle valve has a Viton tip and sticks unless you place an very small wire spring around the base of this needle valve that wraps around the float in the fuel bowl float.  This force the needle valve to open and close with movement of the float.

The next day, the carb was pulled, opened up, and the wire clip installed.


After reassembly, the motor fired on the first crank of the starter.  LESSON LEARNED!

I tested the motor on the water the following weekend, but that will have to wait until next time.