Oil in the bilge

[higgs]

A friend of mine pumped out his bilge recently only to discover a fairly prominant sheen on the water. Suspecting an oil leak, he carefully went over his engine and trans, and only found a little oil - like a couple of drops - gathered at a low point. Trans and engine oil levels are fine. The bilge had been scribbed clean at the beginning of the season. What do you think is the problem?

 

[Ross]

1 half teaspoon of diesel fuel will put a sheen on

a ten foof circle of water. Those few drops could be enough.

 

[Jim]

I think he has a leak

I think it is in the trans. Is it a fine thin redess oil?

 

[higgs]

Once on the water it is pretty tough to tell what type of oil it is. His trans sump is full to the mark as is his engine sump. Ross may be right here. It does not take much to put out a big pool. I have heard onec cup of gasoline will make a slick the size of a football field.

 

[L Callahan]

I found the same thing in the sump area under the

engine where there was a mixture of diesel fuel and water The water was from the exchanger cooling line. With help from a buddy we found that my diesel line clamp to the engine justed needed tighten but I needed to replace the water hose. Total repiar cost $250.00. I was lucky it did not get into the bilge area on my H31, that would have been a real mess.

 

[Stu Jackson]

The intake air filter

and normal aspiration of the crankcase breather hose (depending n what engine he has) may be all that was required.Not necessary to jump to a conclusion that it's a leak.

 

[Timo42]

Florescent dye

one way to determine the source of a leak is to use florescent dye in either the motor or trans. A small blacklight will show even minute seepage. The dye and light aren't very expensive and could save a lot in misdiagnosis. I use this all the time at work. Tim

 

[Robert]

Consider other sources

Thinking outside the box... does the boat have A/C with an oil filled water pump like the CalPump? These make a mess when they come apart. I have never had one last for the full two year warranty.

 

[Mike B]

Oil fill cap

The oil fill cap on my Westerbeke is a push in type, no threads. It leaks just enough to allow a very small drip into the bilge under the engine. You can barely see the oil trail on the engine but it sure is visible once it hits the bilge. Time for a new cap yes, but also another example of how it could happen.

 

[Tim]

Diesel Fuel Line

I had this problem and finally tracked it to a loose pipe clamp at the filter inlet. A very small amount of diesel would come out, migrate down the hose to a low point and drip off behind the engine bulkhead. From there it would make its way to the bilge. Tightened up and now clear.