Oil leak

[island guy]

My friend is without a computer so I told him I would pose his problem. After using his rig he noticed a bit of oil on the garage floor. It seemed to be coming from the area where the prop attatches to the lower unit. Very dark in color. Not much more than a 1/2 teaspoon or so. Any thoughts?

[Ralph Wiggum]

Is it definitely oil? My guess is that it's exhaust "gunk" that will drip out of that area sometimes and is normal.

[PierBridge]

Unburnt fuel exaust is very common and would be my guess or a possible lower unit seal problem.....how does the lower unit oil look, milky?

[island guy]

He had changed the lower unit oil and it looked OK. The stuff leaking is much darker, almost black.

[PierBridge]

Quote:

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He had changed the lower unit oil and it looked OK. The stuff leaking is much darker, almost black.

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Yep we were right sounds like your good to go, if anything BAD happens it's Ralph Wiggum's fault for bad advice "he posted first" and he will personally come over and fix it for you...... ......and I'd hide your beer before he arrive's.

[island guy]

Thanks for the help!! He was worried he may have a seal problem. He is going to take it out on the lake today. He'll keep a eye on things to see if there are any changes.

[Ralph Wiggum]

Just have Grainbelt Premium on hand

If it's really dark and his lower unit lube looked fine, I'd say that Pierbridge and I diagnosed it correctly.

[island guy]

Just curious. Why would exhaust gunk leak out? Does it build up over time and then just leak out over a period of time then stop? My enquiring mind just wonders the reason and whys!

[eurolarva]

Could be a couple of reasons. When gas hits a hot cylinder it condenses and settles to the bottom of the cylinder. This gas is sucked out through a recircuilation system that on newer models will reburn it and on older models (late 60s early 70) will drain it through the kingpin down into the motor leg and back into the lake. Screens can get plugged on reciruilation systems and cause this fuel to drain down the motor leg. Another common cause is when you trailer your boat if you tilt it up the seats in the carbs can not fight the gravity and with existing pressure on the fuel system will overfill the float bowls and then drain down the motor leg. A motor that has not been decarbed will have similar effects where the gas does not get hot enough and will not burn effectivly and go out the exhaust.

[Gus]

I've had this once or twice and it is almost always noticed after the first or second trip of the season. My best guess is it is caused by the fogging oil I used in the motor the previous fall. Just finally working its way out.

[PierBridge]

It's unburnt fuel and exaust it dry's out a little and when it warms up it drip's, we usually hear these post in the spring once it heats up a little.