Strange black oil leaking from engine

[bouner]

I have a 1987 100 Johnson. Everything is good except for when in idle motor drops rpm for a second and then idles good. This happens like every 10 seconds. Also, approximtely 1 hour after use of the boat, black oil/gas comes out of the engine, dont know exactly from where? Im guessing crankcase. Could this be causing the problem at idle? Please comment <br />I put new primer bulb, carb kits, fuel pump diaphram, new lines & plugs.

 

[Cricket Too]

Re: Strange black oil leaking from engine

Where is the oil/gas coming out of the engine? Is it leaking down from behind the prop, from out of the powerhead?

 

[miloman]

Re: Strange black oil leaking from engine

where is the black oil/ gas coming from ie what part of the engine

 

[bouner]

Re: Strange black oil leaking from engine

I can't say 4 sure but I think its from the powerhead sits on the engine. When the engine is running it does not leak the black oil/gas, only after its stop 4 a long period, couple of hours.

 

[Droll]

Re: Strange black oil leaking from engine

If you got a leak in the crankhouse this cound lead to poor idle .<br />By a box " starting fluid " , spray it on the powerhead, on sealings, cracks ,gaskets... ( not in to carbs ).<br />If the rpms respond to the starting fluid You got a leak ,or bad sealings .

 

[Boatist]

Re: Strange black oil leaking from engine

Bouner<br />The black oil behind the prop very likely is normal unburned two stroke oil mixed with exhaust smoke. This is very comon in smaller outboards used for trolling. It will get worse if go over the 50 to 1 oil ratio, idle or run motor slow for long time, or run in colder water. Also will be worse if your thermostat is not working and you motor is running cold. A good quick check is to put your finger on the head. Should be hot but should be able to hold there for about 4 seconds. One other thing that will cause more oil and gas to come out is if the carbs floats and needle valves allow carb to over fill and more than normal gas goes in cylinder. This will also cause it to flood and run bad at idle.<br /><br />To be sure, check and make sure have no water in lower unit.