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1970 Johnson 40ES70A 40HP Outboard

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osdsubzero

New member
Hi Team

I am very new to boating and I acquired a 1970 johnson outboard 40hp. the motor runs fine, I am just having problems with overheating issues. I have changed the complete waterpump. I am starting to think maybe I have put the impeller backwards. but I am debating on that at the moment. I also noticed that when the engine is idling for 3-4mins there is alot of smoke coming from it, Maybe the fuel ratio not mixed properly I don't know. Does anyone have any information in regards to this motor, as I said this is my first boat and I just got my boat licence.
 
The motor will run fine on a 50:1 mix.-----Inspect the thermostat.---Found on top of the cylinder head.-----So is your overheat warning light coming on ?----Is it tested ?----Is it even installed on the boat ?----The smoke is quite normal.----And a lot of water vapor comes out the back at times.----That is often mistaken as overheating.
 
Where are you running it? Ona boat, on the lake? On muffs? In a bucket? It was built to run on a boat, on the lake.
 
I was running it in a bucket of water and the overhead red light came on. I then bought a 2 way ear muffs and also ran it on idle in a bucket of water, it didn't over heat at all and the greyish blue smoke stopped. I ran it for 15mins with out a problem not in gear by the way, the only thing that happened was the motor was missing and engine was bouncing but, I think it needs a good service on the carby. I also noticed that water was spitting out the exhaust and was warm.
 
The impeller MUST be submerged !!----6 or 8 " below the water level.------Too much air / exhaust in a bucket and the pump was never designed for that.
 
Even more than that, that 40 had a thermostat-controlled recirculating cooling system. Water (and air bubbles) return to the pump for recirculation when the thermostat is closed. The pump is a very good water pump, not so good as an air pump. Overall, a very fine cooling system when used as intended.
 
It takes TYPE-C gear oil.----Also marketed by BRP as " premium blend "----Make sure it says for electric shift.-----Is the belt driven generator working and keeping the battery charged ?----It has to be working as electromagnets draw about 2 amps when motor is in gear.
 
Welcome to the forum.
Check when at moderate idle speed and hooked to your battery. It should be showing at least 13 to 14 volts. When at rest, your battery, when fully charged, should read about 12.65 volts. Racer reminds us that the electric shift system will draw currant, so the alternator should be made certain to work and charge. The default for no power to electric shift will allow forward operation of the boat/motor.
 
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Wrong again.-----That electric shift unit does not default to forward with a loss of battery power.-----You start [addling !!
 
That motor has a DC generator, not an alternator. It does not charge at slow idle speed, but over around 2000 rpm, the charging voltage will be about 14.5 VDC.
 
Thanks for the correction, my friends. I remember now it produces DC. Don't think I've worked on one for awhile. So with no power to the shifting unit this one stays in neutral.....so break out the paddle. These were not among my favorites for sure. I believe they started this particular electric shift in 68 and dropped it after 70. As I recall, many units presented to me for repair were destroyed by water contamination. Take good care to keep water out and as my mentors suggest.....be certain the generator is charging.....you should run up your speed often, in order to charge your battery. Keep battery voltage (at rest) above 12.4, or 12.5.
 
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Nope----The electric shift on that 40 came out in 1962 and last ones were 1970 !!-----You have this confused with the HYDRO -ELECTRIC shift that was marketed from 1968 to 1972.-----And I know how they work and in my opinion they are very good and reliable.-----But they are JUNK if you can't find the parts and the grey haired fellow to fix them.
 
Thanks Racer.......guess my hair isn't grey enough yet.....and I waisted my time working on stupid cars and trucks for too many years.
 
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