1978 10 h.p. lower unit rebuild.

[tidechaser 1]

this motor has not been run for a long time apparently. i cleaned the carb out..some yucky oil in it. then i tried to start it..no go..a squirt of starting fluid out of desparation and it ran for a couple of seconds. then i pumped the bulb again and noticed the fuel pump cap had a small crack and was leaking. i was going to order carb,fuel pump aand water pump parts but decided to check the lower unit oil..which of course i should have done BEFORE i bought it.
luckily i got the motor, duck boat and trailer for only 260 so it wont kill me to dump the motor if i have to.
so..pulled the lower plug..and yup..yellowish looking gunk..water in oil. i did not see any water come out but i know from experience that the color means water.
my question is this: should i change the oil and test it in the water after my other work..then pull the plug and see what it looks like?
or do i tear the entire lower unit apart and inspect everything?
i do not have the experience to rebuild it confidently..but i might get a manual and go for it if it is not too big a job.
i could kick myself as i had a manual and threw it away as i thought i would not own another johnson motor..i now have 2 mercs and a yammy kicker.
thanks for your opinions on this.

 

[nwcove]

Re: 1978 10 h.p. lower unit rebuild.

jmo, but id just change the oil, and replace the fill/drain washers for now. then run it and inspect the oil again.

 

[tidechaser 1]

Re: 1978 10 h.p. lower unit rebuild.

not sure what jmo means..but i appreciate the input..i think i will not order much in the way of parts,just the seals for the plugs and the cracked fuel pump cap. then if the motor runs ok and the oil looks ok i will get water pump,new float(it looks nasty but does not seem to leak..yet).
again,thanks...it could just be the plug seals leaking..with my luck it wont be but i will try that.

 

[nwcove]

Re: 1978 10 h.p. lower unit rebuild.

jmo is " Just My Opinion". but i would start with the cheap stuff and check the gear oil after an hour or so of running for water intrusion and go from there. jmo

 

[OptsyEagle]

Re: 1978 10 h.p. lower unit rebuild.

Also, not to nit-pik but I don't think Johnson made a 10Hp in 1978. They were into the 9.9Hp at that time. If that is what you meant, then ignore my reply, if not, give us the model number and we can confirm the model year and Hp of your motor.

I agree with the water issue. Change the LU oil and put in new nylon seals on the drain and vent screws and run it for a while. Let it sit for a day or two and then just open the lower (drain) screw. If there is water getting in it will seperate from the oil and move to the bottom of the lower unit. Let it sit for a day or two because when you run it the gears can mix it up into the oil pretty good and you may not see it as well.