Oil Leak?

[Rookster]

Hi all - hoping for some insight here on a possible oil leak...but I'm hoping its not. I found creamy caramel color water in the bilge of my 3.0L Mercruiser I/O. So far, the information I've found on it, indicates that I have a serious problem with my engine block...such as a crack, allowing water into my engine block and/or oil out of it, and that my engine is toast.

The reasons why I don't think this may entirely be the case, is that my oil level does not drop below the "minimum" mark on the dip stick, the color on the dipstick is normal (black/brown), the color of the oil in the reservoir is also normal, the engine runs smooth, starts smooth, runs at normal temperature (170ish), and oil pressure is between 40 and 55...usually goes up to 55 after I get going and then drops back to 40 while cruising.

But after I noticed that the creamy/caramel/coffee color water in my bilge, I checked the oil level. it was at minimum, so I added about half quart or a bit more. Initially this brought the level up on the dipstick, but after running the boat for about an hour, then letting it sit overnight, the level dropped back to minimum on the dipstick.

Sorry for all the details - just want to give all the context. Just got the boat in the Spring and have been running it smooth and trouble free for a couple months, doing tubing, cruising, etc. So confused and looking for some hope.... Happy to hear your thoughts and opinions on anything that could cause that which doesn't involve engine replacement. Cheers! :biggrin:

 

[tpenfield]

The oil reservoir is for the outdrive (right?)

If you can get a small sample of the oil directly from the engine you can heat it up a bit to see if water boils out of it.

It would be best if you can trace the source of the oil that ends up in the bilge. There must be some tell-tale marks on the engine. It could be an oil pan leak.

When the oil level on the dipstick dropped by a quart over night, did a similar amount of oil end up in the bilge?

 

[Scott Danforth]

im going with rust hole in the oil pan like Ted is eluding to

 

[Rookster]

Thanks for your responses Ted & Scott - really appreciate the help since I was in a bit of a "rookie panic". When I said reservoir, I meant the top of the engine above the engine block, where you add the oil into...through the hole that has a cover on it with the "oil" symbol. Apologies...my engine knowledge and terminology is limited. First boat, and don't do my own work on my car engine. Never even thought of the oil pan being the problem, but it sounds logical...and more importantly, like something that would not cost thousands to fix. Hard to say if oil in bilge from overnight is old or new, because my bilge pump doesn't 100% completely empty the bilge. Perhaps I can place cardboard under the pan overnight though, so will try that next.

Any idea what it takes to replace or fix...being at the bottom of the engine, can it be done by a boat mechanic without removing the engine? Also, I was planning on running it a few more weekends in September before pulling the boat from the water to winterize and service - so as long as it's not gushing oil, would that be too risky even if I check and add oil before each use?

 

[Scott Danforth]

You ad oil to the valve cover

If you have a leak, you take a few hours and pull the motor. And yes, the motor must come out

Your boat, your risk, i wouldnt run it just for the environmental aspect

 

[tpenfield]

Try to narrow down the source of the oil before you determine a course of action, since replacing the oil pan is not exactly a slam-dunk.

 

[Rookster]

Thanks so much guys, will do - also...spoke to my mechanic and they agreed with the oil pan theory, as well as a couple other potential spots (dipstick/tube area or oil pan gasket). They said by the sounds of it I can run it a couple more times before end of the season as long as I watch oil levels very closely...and, best way around the environmental issue is not to pump dirty bilge water into the lake, but into a bucket instead, then disposed of it the same way we'd dispose of dirty oil. Cheers and thanks again for your expertise! :hail: :bump2: