RD-25D 40 HP reconditioning

[sbiegert1963]

I have what I determined to be a 1963 Johnson 40 HP Super sea-horse outboard motor. It hasn't ran in ~30 years and I am wanting to get it up and running to put on a father son boat project. I am not to familar with boat motors but have wrenched on about everything else. I got it dug out and on a stand. It spins over with rope easily with plugs out, jumps compression gauge to about 60 psi in both cylinders with about one compression stroke. I would check for max but doesn't pull very easy with something in plug hole. I checked fuel pump and it was way better than expected. Looks like just needs a new diaphragm and be good as new, automatic choke is operational and carb looks like it just needs a rebuild. My question is, what else should I check before dumping money into this motor? Anything that I need to know? Cylinders look good and doesnt appear its had any water in motor. Should i do more test or just rebuild fuel system and ignition system?
Thanks for any information

 

[Crosbyman]

Well before you...dig in to it the usual is needed . Check for sparks but in any event pull the FW and inspect ignition components... Coils are likely all cracked up and need replacement as well as condensers and plug wires.
See typical cracked coils on a 3hp Wires break in bends also so new wires of 7mm metallic strand are needed (no automotive carbon fiber wires !!)

your best and cheapest book is the johnson service manual will all you need to know for $20
400 + pagesof knowledge . Also visit AOMCI.org where oldies are pampered
carb job mandatory !!

file:///C:/Users/Jacques/Downloads/Johnson_Repair_Manual_Indexed_10th_Ed_1922-1964_12_31_14.pdf

Antique Outboard Motor Club,Inc

www.aomci.org

Magneto parts date back to early 50s and are available. Points... may need just a touch up with 150 grit strip of paper and a wipe with strip of stiff paper & carb cleaner.

check the gear oil for water and replace with 90 grade oil GC oil. see the article in this link for a 15hp refurb. you 40 is in need of similar TLC but not much more complex.

Duckworks Magazine

also see Leroy'S
https://www.leeroysramblings.com/Johnson_35-40.htm

Johnson

Impeller will need a replacement to !

come back with questions as you feel. Great hobby !! nothing hard to do!

 

[sbiegert1963]

Awesome, appreciate the information! Article will definately be a help.

 

[Crosbyman]

oops bad links above and missing pictures ???

1922-1964 Johnson 302231 Outboard Service Manual

Johnson Outboard Motor Service and Repair Manual # 302231 Tenth Edition covers all Models 1922-1964 .pdf download

watercraftmanuals.com

if interested here is are few videos on a 40hp refurbish DO NOT USE A FW PULLER BY PULLING ON THE EDGE !!

 

[sbiegert1963]

That service manual link helped a ton. Looks like I have a huge amount of reading but tons of information. Pictures and video showed up this time. Im getting pretty excited to get working on this motor.

 

[Crosbyman]

print the manual locally double sided and spring bind with plastic cover sheets. enough for 2 binders Be warned you have been infected with the oldies virus. Nobody dies but divorce frequently happens around the 30th engine in the shed. Keep some change for fuel these engines love fuel and oil

 

[racerone]

Do a compression test till gauge stops moving up.----Or pull bypass covers to look at pistons rings.-----A 60 year old motor often needs a complete teardown in my opinion.

 

[Crosbyman]

Posssibly but the beast was dormant for nearly half it's life and may have less than 500 hrs. If the owner TLC'd before storage (oiled) it may need little work to wake it up. A teardown is likely beyond most. I have never been so unlucky as to do open heart surgery .

 

[sbiegert1963]

So pulled the starter off, gave it some TLC and got it functioning like new. Than was able to do a proper compression test. Got 95 psi on both lower and upper cylinders. After compression test I put a little mineral oil in cylinders to let it soak for a couple days.

 

[cyclops222]

Hope the throttle linkage was not misadjusted by a DIY person. All rubber hose / tubing iffy ? Install a fuel / water filter. Done Get lucky.

 

[racerone]

Abandoned , 60 year old motors should be taken apart for complete inspection.----Then you know what you have.---Saves wasted trips to the lake.

 

[cyclops222]

HELP HELP No cell phone service on this lake.

 

[Crosbyman]

virtue is nothing to argue about yet venturing into the innards of the abandoned may be adventurous at best for the non-initiated. Faced with the possibilities of a mishap a small kicker is always a good option .

 

[racerone]

If a boat with 40 HP fits your lifestyle, then learning the workings of this 40 hp will benefit you.-----Then no need for $8000 new motors that require expensive parts and $150 / hr dealer support.

 

[sbiegert1963]

Well since the boat hasn't seen a body of water since the early 90s at the latest. I am guessing I will be making several trips to a test pond for trial and error outings

 

[Crosbyman]

Have you done some bucket testing (with a new impeller) ? save a few trips till it at least idles in a bucket (water above the impeller body)

have you refurbed the ignition per manual and adjusted timing ? . If you do not have the pointy tool the VOM method is just as good. the purpose of the adjustment is to set the openning of the points at the exact TDC which is perfect and the gap openning (.020) becomes less important.

the BASIC method is to set the point gaps at .020 on the highest point of the cam lobe... see manual

 

[sbiegert1963]

Haven't gotten any testing done yet. So far just started a list of parts that I need to replace. Going to pull carb and let it soak for a couple days before a rebuild. Thanks for info on Ignition system. I will update with status after parts start to roll in.

 

[Crosbyman]

for plug wires I have used these but the price has exploded for unknown reasons I have paid 40$ for a set a few years ago. seems it was $69 just a few weeks ago ( tarifs ???)

https://www.napacanada.com/en/p/BMX700175

may as well visit NAPA or a bike shop and buy a few feet of 7mm wire metallic strand plug wire and reuse your plug boots.

 

[racerone]

Don't spend any $$$ until you have determined the actual condition of the motor.

 

[sbiegert1963]

I have an extra set of 8.5 mm MSD wires for a SBC , any reason I couldn't use these?