Where is oil, etc. residue coming out of when docked?

[jbteehee]

I've been noticing that after boating, docking , there is oil residue coming out at prop. Why and where is it coming from? I've got a feeling this question will need much more information from me, but it is a start! Thank you, "just a gal boating, fishing, and doing all the work herself!

 

[H20Rat]

What type of engine?

Is it actual liquid oil or is it soot?

If it is actual liquid oil (most likely blue), you probably have a leaking shaft seal. Very likely you sucked up some fishing line. If that is what it is get it fixed ASAP, it is going to get expensive otherwise. (if oil is flowing out, water is also flowing in. Your lower unit gears don't appreciate water on the inside!)

 

[tpenfield]

Outboard? 2-stroke, 4-stroke? I/O ?

engine type details would be helpful.

 

[jbteehee]

1988 4.3l v6 mercruiser inboard. It's blue looking.

 

[Bondo]

1988 4.3l v6 mercruiser inboard. It's blue looking.

Ayuh,..... Welcome Aboard,..... Sounds like a bad seal, or seals in the outdrive,.....

Pull the drive for a closer look,.....

 

[Bt Doctur]

Blueish could be gear oil

 

[harringtondav]

Based on your info, I agree with the previous diagnosis. Bad prop shaft seals or bad drive shaft seals.

I'm not stereotyping your mechanical abilities. But these are difficult DIY repairs for anyone without three special tools. You can remove the prop shaft seal carrier with a large punch and hammer. If you have to go deeper it's probably time to go to a Merc shop.

 

[wellcraft-classic210]

Performing a pressure test on the out drive will indicate if a leak is present -- Its not to hard if your able to work with and arrange the threaded fittings // etc. -- check the stickies for added info.

 

[QBhoy]

Likely worth suspecting the power trim fittings and rams. If it’s worse or bad when raising or lowering engine then bingo.
Other possibility is also as mentioned above and gear oil.
Less likely would be that it’s unburnt fuel and you are running rich.
Even less likely I hope is that your bilge is a bit oily and your taking on loads of water and the bilge pump is running loads. Hopefully not ! Haha.

 

[H20Rat]

Blue oil pretty much confirmed it. Very likely shaft seals on the lower unit, and I'd bet it is from fishing line.