Motor ID and Parts Interchangeability 40hp Johnson and Evinrude

[AlexeiVT]

Hello,
I recently acquired a Johnson 40 HP Electric Seahorse outboard, Model# RDS-28, Serial# 2166453...and would like to know a bit more about it (year it was made, and how it compares to other similar motors in the line).

What I do have, that is functional and reliable (though missing some parts, that I'd like to cannibalize from the new, nonworking compression-less Johnson) is a 1964 Evinrude Big Twin 40 HP (that the folks here were so helful in getting it up and running).

What I'd like to know, is what is (or definately is not) interchangeable between the two, since at first glance they look similar.

Specifically, the parts I'd want from the Johnson are as follows:

the electric starter, starter bracket, and toothed ring gear (as my motor currently doesn't have those).

possibly the head w/ spark plug holes (mine currently is holding compression despite rthread inserts on both plug holes...though the donor Johnson looks almost like it has mechanical lifters or something, as there is a spring loaded protrusion adjacent to each plug hole, plus a bracket that swings to mae contact w/ them, that has a threaded end adjustment...what else connects to this rod is unknown and missing).

last set of parts would be the propeller and foot housing that coverls the lower gears (also the clutch dog, as well as any other miscellaneous lower unit gearing and parts would be nice as spares on hand).

Thanks for any help and suggestions

(the "donor" Johnson has been setting on the ground sideways for the last decade, and the owner previous to that never heard it run either...the flywheel turns quite easily w/ no resistance when in neutral, therefore seemingly no compression, and my inexperience suggests possibly a blown gasket, broken ring, damaged valve, or something bigger/worse).

(also, when put in any gear, it's the same scenario, everything just spins way too easily, plus the plate under the flywheel w/ the points on it looks super wobbly...my thinking is that it's likely something fairly catastrophic happened way back when and took some internals out...but any tips on what to look for would be great...cosmetically, it's sure alot nicer than what I've got running, but at least my ugly motors still going).

 

[WillyBWright]

Re: Motor ID and Parts Interchangeability 40hp Johnson and Evinrude

The Johnson is a 1966. The Evinrudes and Johnsons are virtually identical. The hoods look different, but they still swap. That's the biggie. Oh yeah, and paint. The valves on the Johnson are compression relief valves for recoil starting. I always found them to be of little to no value. I'm betting the Johnson had busted rods.

 

[JB]

Re: Motor ID and Parts Interchangeability 40hp Johnson and Evinrude

I come up with 1966 for your Johnny, but everything else agrees with what WillyB said.

 

[AlexeiVT]

Re: Motor ID and Parts Interchangeability 40hp Johnson and Evinrude

Thank you very much gentlemen for your speedy replies.

Since they parts are compatible, there will no doubt be more questions down the road.

But a few to start...on the Johnson's compression relief start recoil pieces in the head, will that head w/ the spark plug holes, still swap on ok to the Evinrude (the evinrude just has the plug holes, nothing else)...also, since whatever attaches to the piece that articluates and actually pushes against those rods is gone, will that be an issue?

Also, if busted rods...short of a teardown, is there anyway to more definitively diagnose it...or do all the symptoms described pretty much point to that as the most logical failure that wipes out both the compression and the movement of the propeller despite things being engaged in gear (or possibly, multiple failures).

Thanks.

 

[samo_ott]

Re: Motor ID and Parts Interchangeability 40hp Johnson and Evinrude

Even with bust rods turning the flywheel in gear should turn the prop. Are you sure the engine is turning over at all? Maybe the flywheel key is sheared off or missing? Best bet is to remove the head to see what's going on inside.

The rod that runs from recoil start to the head is the compression relief. Many engines have just removed this feature. It lowers the compression in the engine when pulling the recoil starter by opening the little valves on the head and adding more volume to the cylinder thus lowering the compression and making it easier to start/pull. If you plan to use electric start mostly you don't really need it.

I have 4 x 40's ranging from 1960 (first year) to 1966 and they're pretty much the same.

 

[AlexeiVT]

Re: Motor ID and Parts Interchangeability 40hp Johnson and Evinrude

Thanks again samo,

What you said makes sense...and seems to not be as dire a situation as pedicted (I got to thinking, that what would the chances of both rods being broken be...and furthermore, it'd seem like I would at least hear some sort of clanking going on down below).

I'll pop things apart and inspect them, since as it is right now, the flywheel just spins around w/ no effort at all, and it makes no change to that regardless of being in or out of gear...would sure be a simple enough solution (granted, the 10+ years of laying there doesn't help, but it puts in the same situation as my other motor before it was running).

So the compression relief things are just a luxury, and not essential to the starting? good to know it'll work...as it is, the 40 HP Evinrude doesn't have those reliefs, and has been stripped of the electric start...once it's warmed up, it starts easily, but those cold starts, and cranks, make onlookers laugh I'm sure (I've just been squirting a bit of premix down the throat of the carb, and that seems to get it going...I've done the link synch, but despite that, I can never get this thing quite right...if I adjust the lean needle, the only adjustment, on the carbs to get it to idle low enough to permit shifting from F to N, then I can never get it to start up easily again when cold...if I get it adjusted to start well cold, it never idles low enough to shift to N...what I end up doing is just about killing the idle, quickly timing the shift, and bringing the RPMs back up...obviously not the ideal situation, and I'd like to rectify it, but on the pond it's not so big and issue, but I have more fierce waters planned to conquer, or play in, and it's a drag when you wipe out being towed, and have to climb back in and pull start the motor for your driver, or worse yet, try an in the water pull, scary enough to avoid doing again in time to slap the skis back on).

 

[AlexeiVT]

Re: Motor ID and Parts Interchangeability 40hp Johnson and Evinrude

You're right again.

It's dark out, so all I could do was find my way to motor in the backyard, play w/ the shift lever, and try to turn the prop w/ my foot.

Sure enough, things definately offer fair reistance, but still turn (good on two points I guess...internals intact, and also not frozen together)...maybe it's too early to call it a parts motor just yet.

 

[AlexeiVT]

Testing the starter motor?

Testing the starter motor?

Also, figured rather than start a new thread on this motor, another question answered should tide me over for a while.

After I lube up the cylinders and let things sit, I'll want to see if this electric started actually works...what is the procedure and hookup, and anything to watch out for in testing?

The motor has an "original" harness, w/ the obvious black/red, -/+ leads...but it also has another 4 wire clip connector (is that connector for the charging system)?

Is it a safe bet, that I can just hook the larger black and red wires and determine whether it works based on that (or is there something integral to the circuit that requires power to the other smaller gauge wires...like trying to test an electric clothes dryer motor).

Thanks.

 

[AlexeiVT]

Re: Motor ID and Parts Interchangeability 40hp Johnson and Evinrude

It seems it's the flywheel key (apparent now, as I see that it spins and the bolt/shaft it's on doesn't).

The starter also seems to work (wow, nice to not have to pull all the time).

A question I have, goes back to those pressure relief valves in the head for the recoil starter.

I lubed up the cyclinder walls, just to turn things over by turning the prop, compression seems fine...but I notice that those relief valves aren't making for a complete seal, as I can hear the air hiss out around them when I turn things manually.

Perhaps they will loosen up and seat, or is there something more agressive I should try...or, can I just plug them up w/ a bolt?

I'll be giving things the royal Sea Foam treatment, as it get's closer to firing up.