1969 55hp Lower Unit

[bailnutzHUNTER]

I know much about vehicle engines and am mechanically inclined but am kind of new to boat motors so I have a few questions....
-I have a 1969 55hp johnson, I was wondering if anyone knows what the lower unit oil capacity is or should be?
-What would be a recommended gear case oil to use?
-When it is time to fill, being this lower unit with the 3 plugs, do I still fill it the traditional way, from the bottome unitl it comes out the top?
- I have a real small leak coming from behind the prop, could it be a propshaft seal leaking? If so how hard is this to replace?

 

[cougar1985]

Re: 1969 55hp Lower Unit

I know much about vehicle engines and am mechanically inclined but am kind of new to boat motors so I have a few questions....
-I have a 1969 55hp johnson, I was wondering if anyone knows what the lower unit oil capacity is or should be?
-What would be a recommended gear case oil to use?
-When it is time to fill, being this lower unit with the 3 plugs, do I still fill it the traditional way, from the bottome unitl it comes out the top?
- I have a real small leak coming from behind the prop, could it be a propshaft seal leaking? If so how hard is this to replace?

you have the 3 cylinder loop charged 55 hydro-electric shift johnny,an excellent motor.if you suspect a propshaft leak you need to get a manual and adress that pronto,thats the death knell for electshift models ,WATER INTRUSION!its really not hard to do atall.use omc premium blend gearcase lube,its not the same as other standard gear oils so dont confuse the two.use new washers on the filler screws after filling ,they are a one time use part.1968-1969 55 hp omc takes 25.3 ounces of premium blend gear oil.there are only 2 plugs dont touch any others!the vent is above the cavitation plate and the filler/drain plug is just below the gearcase and both are slotted screws!fill from lower till it comes out the top one.

 

[cougar1985]

Re: 1969 55hp Lower Unit

to add to my post ,when you say a small leak exactlly what do you mean?water could be just normal ,gear oil mixed with water bad.check your lower unit oil closely for water if none is present maybe all your seeing is the excess water from the prop exhaust.

 

[bailnutzHUNTER]

Re: 1969 55hp Lower Unit

Well it was a small puddle when I parked it in the garage in between uses, maybe a quarter size puddle.(last summer I bought the motor from a guy who said it runs great). When I did drain the lower unit there was no presence of water being there, thats why I'm not so sure the seal is bad. The motor shifted great. The only problem I had with the motor last year is starting it. I would have to crank it quite a bit to get it to fire up. What I did notice is that it calls for
L77JC4 plugs, meanwhile the previous owner had QL77JC4 plugs in it. I know the Q series is a resistor type plug created, having something to do with frequencies. Could the difference between the plugs be why it was starting hard? When it was running, certainly didnt seem like it was missing on any cylinders. Oh and to mention, the owner before had replaced all the wiring, and he had a manual to do so, he also gave me extra parts like a good starter, wiring harness, and a lower unit that had good soleniods in it.

 

[Tim Frank]

Re: 1969 55hp Lower Unit

I know much about vehicle engines and am mechanically inclined but am kind of new to boat motors so I have a few questions....
1) -I have a 1969 55hp johnson, I was wondering if anyone knows what the lower unit oil capacity is or should be?
2) -What would be a recommended gear case oil to use?
3) -When it is time to fill, being this lower unit with the 3 plugs, do I still fill it the traditional way, from the bottome unitl it comes out the top?
4) - I have a real small leak coming from behind the prop, could it be a propshaft seal leaking? If so how hard is this to replace?

1) About a pint and a half.
2) Use only Type "C" gear oil in this motor.
3) There are only two "plugs" that should be involved. Be really careful and make sure you know which 2 are in-play. The third will be a landmine, and you don't want to step on it.
4) You could pull the prop to get a better look, but make sure that it isn't just from the exhaust. If there isd no water getting into the gear oil, it may not be a problem unless oil loss is significant.

 

[Tim Frank]

Re: 1969 55hp Lower Unit

L77JC4 plugs, meanwhile the previous owner had QL77JC4 plugs in it. I know the Q series is a resistor type plug created, having something to do with frequencies. Could the difference between the plugs be why it was starting hard? When it was running, certainly didnt seem like it was missing on any cylinders. Oh and to mention, the owner before had replaced all the wiring, and he had a manual to do so, he also gave me extra parts like a good starter, wiring harness, and a lower unit that had good soleniods in it.

Stay away from the surface-fire plugs.
You would have been at the time for a rewire if it had not been done. The insulation breaks down and causes havoc with the ignition system, and their ignition systems were iffy anyway.
At best those motors were a challenge to start. Once running they were a thing of beauty.
Had a '68 for 40+ years; great motor but seldom was a "jump in the boat, turn the key and go proposition"...

 

[bailnutzHUNTER]

Re: 1969 55hp Lower Unit

Hey thankz for all the info. The motor being as old as it is, I thought the hard starting wsa typical. There is one plug on the bottom(that has nothing written next to it) And there are two plugs on top, one saying "oil level" and the other right above it saying "vent". These two plugs are above the cavitation plate. There is only about an inch between the two. So the plug on the bottom isnt used to drain?

 

[cougar1985]

Re: 1969 55hp Lower Unit

Stay away from the surface-fire plugs.
You would have been at the time for a rewire if it had not been done. The insulation breaks down and causes havoc with the ignition system, and their ignition systems were iffy anyway.
At best those motors were a challenge to start. Once running they were a thing of beauty.
Had a '68 for 40+ years; great motor but seldom was a "jump in the boat, turn the key and go proposition"...

really?my 68 was a jump in the boat ,turn the key and go all day every day motor!wish i still had her, it ran great!

 

[Tim Frank]

Re: 1969 55hp Lower Unit

really?my 68 was a jump in the boat ,turn the key and go all day every day motor!wish i still had her, it ran great!

You did well then. Everyone I know who owned one had starting complaints. They did run great once going, no question.

 

[Tim Frank]

Re: 1969 55hp Lower Unit

Hey thankz for all the info. The motor being as old as it is, I thought the hard starting wsa typical. There is one plug on the bottom(that has nothing written next to it) And there are two plugs on top, one saying "oil level" and the other right above it saying "vent". These two plugs are above the cavitation plate. There is only about an inch between the two. So the plug on the bottom isnt used to drain?

Lower plug is the drain/fill plug. "Oil Level" is the other.

 

[bailnutzHUNTER]

Re: 1969 55hp Lower Unit

Hey thanks alot, I am glad I didnt hit that "landmine" I know exactly what you are talking about though, I had 35hp chrysler that had a few extra screws and a couple mentioned in the manual that said "DO NOT TOUCH"