Oily substance in the main bilge

[Gary Scheier]

We have a 1991 Hunter 28 with a 2gm20f engine. We just got back from a trip on San Francisco Bay, with about an hour of motoring. This morning, I noticed black water in the main bilge. It seems like emulsified oil, but it does not float on top of the water. Strangely, there is no sign of any oil in the separate engine bilge or on the engine pillow. I just had the engine serviced, and I noticed that they did slightly overfill the engine lubricating oil. There are no signs of oil in any of the other bilges (packing gland area, forward compartment) and no sign of oil under the engine??? I checked the archives, but didn't find anything on point.

 

[Steve Dion]

Could it be?

Gary:This seems weird. Their are only a couple of things that seem reasonable. First, do you think it could be some type of algae growing in there and you did not notice it? Put a little bleach and water in there and see what happens.Second, do you think it may be belt dust. If you belts are loose they tend to throw off this dust. It will get all over the engine compartment and of course makes it way into the bilge. This stuff looks like soot but its not. I assume that it does not float either.

 

[Rob Sherrill]

Check the fuel filter

That happened to me on my 27. It turned out that the fuel filter was just a bit loose and allow some fuel to mix with the water and loosened up some of the old oil on the walls. It was a very small leak and only required a slight turn to stop it.

 

[Jim McCue]

wash residual ?

Perhaps the yard that serviced the boat used some detergent to "clean" up the mess they made in your engine compartment and it washed it between your ribs. then with some H2O evaporation it concentrated some and with heeling in the Bay, it made its way thru the outer weep holes in the ribs- then you finally noticed it in the bilge. Just a thought

 

[Carl Senos]

Two More Wild Guesses

Does your ice box or shower sump drain into the main bilge?