1979 55HP Johnson

[cptdondo]

I just got the boat with this engine on it. We were working on the boat and noticed gasoline leaking out of the airbox. A steady small stream. Thinking it may be the carb bowl draining, we lowered the motor.

A little while.later I noticed a black oily sooty stuff leaking around the prop. I suspect that's gasoline too. Is this a good guess?

But why is it leaking in the first place? It was a lot more gas than would fit in the carb bowl.

Lastly I checked the gear lube in the foot. Is is clean and clear. No water. So seals should be ok. How does one go about checking level and changing the lube?

 

[rolmops]

You should certainly go over the carburetor and make sure that all the hoses are in good condition. You may have chanced on pre 2000 rubber which is not ethanol resistant and may have partially rotted out. and all the nuts and bolts should be properly fastened. As for the black stuff dripping down, That is partially burnt fuel which you will always find in the exhaust of a two stroke. It is nothing to worry about

 

[Crosbyman]

couple things...oily soot is just carbon deposit washout and should eventually stop in nothing abnormal top side.


fuel leak..excessfuel leak with engine tilted up can happen with full carbs but a carb should normally stop the inflow of fuel if the inlet needle closes properly... if the float shuts it.

Carbs also have air breather passages to balance air pressure in the carb.... basically they prevent vacum build as the engine sucks in the fuel up...... by letting air inside the carb bowl to replace it sucked in with the fuel . IF the engine is tilted all the way up fuel could drain out .

GC oil should be drained out by unscrew top and bottom screws. NNew oil should be pushed in from the bottom until it comes out on top where the top screw is installed. This helps the oil from draining out to fast on the bottom screw while you quickly reinstall the bottom screw.

use new washers (nylon) when changing the GC oil to ensure good sealing.


you should get a maintenance manual for your engine but if you want a book for 20$ that explains the basics on older generation motors (but not your 55) this one is a good read.

1922-1964 Johnson 302231 Outboard Service Manual

Johnson Outboard Motor Service and Repair Manual # 302231 Tenth Edition covers all Models 1922-1964 .pdf download

watercraftmanuals.com

you have numerous utubes available to show you how things work
here is one general video on carbs

btw you need to inspect/replace the impeller if age is unknown. 3-5 years is the usual time to replace depending on use and NEVER run the impeller dry !!!

 

[cptdondo]

You should certainly go over the carburetor and make sure that all the hoses are in good condition. You may have chanced on pre 2000 rubber which is not ethanol resistant and may have partially rotted out. and all the nuts and bolts should be properly fastened. As for the black stuff dripping down, That is partially burnt fuel which you will always find in the exhaust of a two stroke. It is nothing to worry about

Yeah, the previous owner (the guy I bought it from) told me he rebuilt the carb but didn't really know what he was doing, so tearing it down is on the agenda for the next couple of rainy days. All the lines look good visually.

Fortunately we're fresh water, and most boaters run ethanol free in their boats (and snowmobiles). That makes life a lot easier.

 

[Crosbyman]

I have use ethanol fuel all my boating life since sold & currently in my 75HP ETEC never had any problems and the boat is stored 6 months fully fueled with 87 octane + fuel saver cycled in before storage.

don't tilt up to much if not needed and see what happens.

 

[cptdondo]

GC oil should be drained out by unscrew top and bottom screws. NNew oil should be pushed in from the bottom until it comes out on top where the top screw is installed. This helps the oil from draining out to fast on the bottom screw while you quickly reinstall the bottom screw.

use new washers (nylon) when changing the GC oil to ensure good sealing.

Interesting. I didn't see any washer, oring, or such when I removed the upper screw. Time to go by the marine place.

btw you need to inspect/replace the impeller if age is unknown. 3-5 years is the usual time to replace depending on use and NEVER run the impeller dry !!!

Yeah, I just watched the video on this. A bit involved for an afternoon project. It seems to be spitting water OK for now. Maybe a winter project.

 

[Crosbyman]

pull up some UtUBES... an impeller change is not a big job

just keep an eye on PH overheats to save an impeller !

 

[racerone]

Best to test the overheat warning horn.

 

[cptdondo]

Best to test the overheat warning horn.

How do i do that?

 

[cptdondo]

I found the factory service manual on Ebay. Yay!

Also found that the drain hose from the air box is missing or disconnected. More work to do.

 

[racerone]

Find sensor ( tan wire ) on the cylinder head.----Slide the rubber sleeve to expose wire clips.-----Turn key to ON.-----Touch metal of tan wire to a head bolt.----Horn should sound.