Johnson 5.5 leaking gear oil

[scoots]

Several years ago I acquired and rebuilt a 1955 Johnson CD-12 and the pressure tank that goes with it. The 5.5hp outboard starts easy and runs great. However, I have to transport the little outboard to the lake in my pickup as my small boat is a car topper. The little Johnson lays on its back in a special duffel bag …. and it’s there that I find the gear case oil that has leaked during transport. Not a lot, but enough for concern.

Anyway, making a long investigative story short, I believe the gear case oil is leaking thru the water intake (?) at part #29 (corrected typo – sorry) in the accompanying photo. Is this normal or is there something that I need to re-seal? No leaks when mounted on its stand in the shop, where it will sit all winter.

[beerman57]

#28 is the locating pin for the gearcase head. Is it basically black what you’re seeing, that’s unburned fuel that collects, my older motors drip it sometimes. If it looks kind of like honey (or the oil you put in it) then it’s leaking out of the shift shaft seal or the drive shaft seal. Let the motor sit straight up and down, in running position, for a day or 2. Then crack the drain plug till a little oil / water / milky oil runs out. If it’s water at first or milky oil, you have a leak.

[frankr]

If gear oil is coming out the #29 water inlet screen, it most likely is coming from the drive shaft seal #22. The screen leads to the space under the water pump, and that’s where the drive shaft seal is located. Do you see anything coming out the long narrow plate on the side of the gearcase? That is in the same passage.

However, the inlet screen is right close to the exhaust outlet. It would be reasonable to think you might be seeing oil draining from the exhaust. That is the oil that you put in the gas that has gone through the engine, done its job and discharged out the exhaust system where it picks up carbon particles that turns it black. All perfectly normal.

[fleetwin]

Have you drained, inspected, and changed the gear lube? Any signs of water?

[Mumbles]

If it’s unburned motor oil and coming out of the exhaust snout, check the small drain hole right in front of the prop and underneath the A/V plate. If it is plugged, the oil can pool up inside the gearcase housing during storage and run out when the motor is tilted over. As stated, if it’s coming out the screened water intake, suspect a leaky driveshaft seal.

Something else to think about is since these motors run on a 16/1 fuel mix and tend to run cold by not having a thermostat in the system, an oily sludge tends to build up in the exhaust housing, especially if the motor is used mostly for trolling, and then slowly drips out while the motor is stored on a rack. This is the stuff which makes a mess on the floor.

Here’s a diagram of your ’55 CD showing the location of that elusive drain hole.

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[Doug Wilson]

my guess would be drive shaft seal but could also be the shift shaft seal. My CD-16 that I resealed last year does not leak at all in any position. I just noticed last weekend my QD-19 leaked when laying on its back have not had it apart to check yet.

Doug

how is it motors multiply when the garage lights get
turned off?

[sailor58]

The top IPB is not the correct one for your motor, but the one Mumbles is showing is. Note part #14 in his IPB, the top IPB doesn’t show it. My ’56 Johnson 5 1/2 would leak gear oil whenever it was laid down. I found that the gasket #13, that goes underneath part #14 had failed, and oil was leaking there. I found this out after replacing the top driveshaft seal, and the lower unit continued to leak gear oil.
HTH.
Larry

[dan-in-tn]

Very simple to tell if it’s gearlube vs gas/oil residue. Just smell/taste it? Gearlube has a very pungent odor/acrid taste. Of course I think everyone has tasted gasoline. Try to avoid that these days! A pressure/vacuum test should prove the leak.

Dan in TN

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