Black oil spraying under cowling

[kellaig]

Hi there,<br /><br />I have a 40 Hp honda that has small drops of black fluid that has dropped onto the fuel filter and around it . It looks like it has been blown on. some similar oil spots go forward from this.<br /><br />I can't seem to see where it is coming from. There is also some on the inside of the cowling on that side?<br /><br />Any suggestions<br /><br />Regards<br /><br />Kellaig

 

[hondon]

Re: Black oil spraying under cowling

You have probably noticed ,that while these things warm up ,they can give a few little snorts.Those snorts are a lean backfire caused by the fact that your cumbustion camber is not yet hot enough to vaporize the fuel /air mixture entering it leading to incomplete combustion.When that little snort happen it is coughing out a little partially burnt fuel into the air silencer that has its main air entry right in the area you describe.How is everything running?

 

[Skinnywater]

Re: Black oil spraying under cowling

I get the same thing with my 50. I've traced it to the grease on the throttle linkage.

 

[Skinnywater]

Re: Black oil spraying under cowling

kellaig, I did my 200 hour maintenance today.<br /><br />I was able to take a better look into where the oil spray is coming from. <br />What I found is the crankcase ventilation tube comes from the valve cover to the top of the air silencer. Here the crankcase gases are vented to be pulled into the carbs with the intake air.<br />Some oil vapor is collecting and seeping at the bottom of the silencer box and is being vibrated off onto the accelorator linkage and fuel filter.<br /><br />At the rate it collects I'm not seeing a problem.<br />Although the harder an engine is run and the more wear it gets,the more crankcase pressure it has.

 

[kellaig]

Re: Black oil spraying under cowling

Thanks Hondon and Skinnywater,<br /><br />The outboard is at the mechanic having its 2 year service. Is this a normal phenomonen or is it a precursor to something else. Do all hondas do this or is there something wrong???<br /><br />Regards<br /><br />Kellaig