Johnson 40hp

[Duke124]

I am new to boat motors and I was wondering how I could find out the year on this motor?

Also, where could I download a repair manual? I wanted to replace the water pump. (maintenance)

Very slow crank, but I am pretty sure it is the starter. Checked battery--12.4v checked power to the starter--12.4v--no voltage drop. With plugs out it turns over fast though.

Also, I am not familiar on lower units. I put it into forward and the prop barely moves. I checked the gear oil--none. Not sure if the previous owner drained or what. My questions is how is the prop driven? Gear? Does it sound like I might have some issues?...with the lower unit that is!!!

Thanks

 

[engine391]

Re: Johnson 40hp

What is the model number? Need to know that to get the exact year. You will find the tag on the transom clamp. It will have the model and serial number listed.

 

[Duke124]

Re: Johnson 40hp

Rkl 30 d
j2901302

 

[Topol_86]

Re: Johnson 40hp

your motor year is a 1968

 

[Duke124]

Re: Johnson 40hp

Ok, so it is a 1968 Johnson 40hp

I got the lower unit off. How "serviceable" is it? can you take it completely apart and check for damage/wear?

I took the prop off, cap, and retaining clip. Can you take all that out? How?

 

[tx1961whaler]

Re: Johnson 40hp

Ok, so it is a 1968 Johnson 40hp

I got the lower unit off. How "serviceable" is it? can you take it completely apart and check for damage/wear?

I took the prop off, cap, and retaining clip. Can you take all that out? How?

That is an electric shift lower unit. I wouldn't monkey around with it without a manual. Even with a manual, really. It does need oil to shift properly, and the electrical system measurements should be made first. The lower unit uses Type C lubricant for electric shift lower units. Seriously, if you go tearing into that thing without knowing what you're doing it could be an expensive lesson....

 

[tx1961whaler]

Re: Johnson 40hp

For the starter, make sure the battery is fully charged and make sure every connection from the battery terminals to the engine is clean and shiny, including the ground connection to the block. It is possible to use good jumper cables (both pos and neg) to directly power the starter to make sure it really is the starter that is the problem. Most of the time it isn't.....these old cables corrode from the inside out a lot of times.

A 1968 uses a 50:1 gas to 2 stroke oil ratio.

 

[Duke124]

Re: Johnson 40hp

Is the a seal/gasket "kit"or for the lower unit or do I have to purchase all the seals seperately?

 

[Duke124]

Re: Johnson 40hp

Is the a seal/gasket "kit"or for the lower unit or do I have to purchase all the seals seperately?

Also, where is a good source for parts?

 

[Duke124]

Re: Johnson 40hp

After removing the gearcase from the lower unit, I noticed that one of the wires that go into the gearcase was disconnected and both wires were exposed and the insulation was cracking and missing on half the wires! Probably my problem.

However, now I have to dig into the gearcase. I ordered a Johnson factory manual. Does anyone have some experience with the electric shift gearcase?

Thanks

 

[Topol_86]

Re: Johnson 40hp

I could give you the half fix my brother and I used on his motor a few years back but due to the vast knowledge available here I feel I'd be going against one of the very reasons Iboats exist, and that is to provide free knowledge to do the job right, so I'll refrain. I will however continue to watch this thread as his motor is acting up again.

 

[tx1961whaler]

Re: Johnson 40hp

However, now I have to dig into the gearcase. I ordered a Johnson factory manual. Does anyone have some experience with the electric shift gearcase?

Thanks

Yes. F_R probably has more repair experience than I do, but I have owned and maintained a couple of them over the years. Wait for the manual and study it before opening the gearcase up. With any luck, you can just replace the wires at the coils and it will be OK. This system has (2) coils, one for forward and the other for reverse. Energizing one (and ONLY one!) of the coils causes a spring to tighten around the prop shaft and makes it turn in that direction. An oversimplification for sure, but that's the basic idea of it. Most of the parts are actually still available, but are hellishly expensive.
The shift switches in the control are also an issue, as they break and are not available new anymore.

Diagrams and parts are at:
http://shop2.evinrude.com

 

[Willyclay]

Re: Johnson 40hp

I noticed that one of the wires that go into the gearcase was disconnected and both wires were exposed and the insulation was cracking and missing on half the wires! Probably my problem. Thanks

Forum guru Joe Reeves told me OMC changed suppliers of wiring harnesses in 1968 and bad insulation is a problem with motors built that year. My 100HP Johnson is the same. Good luck!

 

[Duke124]

Re: Johnson 40hp

Update: while examining the gearcase I was able to snag the loose wire for the rear magnet and pull it up! I replaced the wires where the insulation was coming apart, which was most of the wire. Using the old seals, I put it all back together and filled with type C oil .....

It works great!!!

I couldn't run it that long because I was worried about the water pump. Where does the "tell-tail" come out?
Where is the water inlet?
I thought it was on the left side of the motor. I put ears on and couldn't find the water outlet. I didn't want to risk overheating the motor so I shut it off.

I had inspected the water impeller and it looked ok. wasn't brittle. Could it still be bad? I had planned on replacing it if I could fix the lower gearcase.

I also picked up a new battery and it cranks over great. Fires right up!

Thanks

 

[Willyclay]

Re: Johnson 40hp

It works great!!! I couldn't run it that long because I was worried about the water pump. Where does the "tell-tail" come out? Where is the water inlet?
I thought it was on the left side of the motor. I put ears on and couldn't find the water outlet. I didn't want to risk overheating the motor so I shut it off. Thanks

Wow, you are very lucky! The electric shift is great when it works. No "tell-tale" on that motor, At idle, a fine mist should be noticeable at the Exhaust Relief Outlet on the rear housing about halfway between the Anti-Ventilation Plate and the powerhead. More at speed in the water. Muffs are not recommended for that motor because the only place water can enter the system is the Bypass Inlet which is just above the AVP. The main water inlet is behind the prop on the lower surface of the AVP. Tempo used to make a hose adapter device that fit on it. I modified a spare Bypass Inlet plate with a hose fitting and used it for many years with no problems other than the inconvenience of having to remove the "useable" plate when I needed to run the motor on the hose. Good luck with that great old motor!