I noticed there was a bit of oil in my bilge area after a day on the lake last weekend. I know the bilge area was pretty dirty, so it may be that. But I went and checked the oil today and I'm not sure where I stand. The dip stick looked good -- I think. The inside of the oil fill area looked a little grey. I attached pictures. I know there is a small crack in the water jacket, but my mechanic said that's all it is, and it's tiny - he wasn't worried about it. The guy I bought the boat from stored it outside with no cover. And the gas tank had quite a bit of water it in too. Could water have gotten into the top of the engine from rain? And at the end of the day, what should I do to clean it out? And do I need to clean it up asap?
Water in my oil?
- Thread starter caphilli
- Start date
BillK2632
Well-Known Member
From the pictures, the oil on the dipstick looks fine to me. The inside of the fill cap looks like it is from condensation that forms under the valve cover, it can give the little bit of oil that remains there after a shutdown a milky look. A boat that is used for shorter periods tends to see this more. If the boat has been stored outdoors without a cover - and the oil has not been changed, it could explain this. The crack in the water jacket is concerning though - you need to watch that. A classic sign of a cracked engine block or manifold is water mixing into the oil. If enough is getting in there, the oil will start looking like a chocolate milkshake and the oil level will rise. I have seen engines with so much water in them it was coming out through the dipstick.
Assuming the oil has not been changed recently, it looks to me like you have collected condensation in the oil from the boat sitting outside uncovered.
If it were me, I would:
Change the oil.
Pull the plugs and inspect to be sure no water has been getting into any of the cylinders.
Run it!
Monitor the oil level.
Monitor the oil for water - if you have a crack it will start showing up real quick.
Assuming the oil has not been changed recently, it looks to me like you have collected condensation in the oil from the boat sitting outside uncovered.
If it were me, I would:
Change the oil.
Pull the plugs and inspect to be sure no water has been getting into any of the cylinders.
Run it!
Monitor the oil level.
Monitor the oil for water - if you have a crack it will start showing up real quick.
Ah, okay. That's semi reassuring. The man I got it from said the oil was changed about a year and a half ago, run once, and then it sat outside and uncovered here in the south - where the humidity is crazy. So the condensation could be it. I'll change the oil this weekend before I take it out and see what we've got.
It's a 3.0L Mercruiser, 1984 engine block (I know, it didn't make sense to me). How much oil do I need? And what weight?
BillK2632
Well-Known Member
I would just use the Quicksilver 25w40 - which is the OEM branded oil. I think the 3.0 holds 4qts. Not sure what filter you have - just take a look at the one that is on it. You can get the Quicksilver oil and filters an WalMart. I would change the fuel filter while you are at it if you have not - especially since you had water in the fuel tank.
Thank you! I will check out walmart. Is there a specific size filter I need? Or are they universal? And yes, I have an extra fuel filter and fuel water separator. The mechanic drained the fuel tank and everything ran fine last weekend. But I'll check everything one more time.
BillK2632
Well-Known Member
I think the filter is this one - 35-866340Q03 - which is supposed to fit all Mercruiser sterndrive/inboard engines except the 4.3v6 without a remote oil filter (that's what I have and it uses a different filter). You can get these at WalMart, but I would check what you have on there now. Never owned a 3.0 so I am not 100% sure.
I appreciate your help! If the oil doesn't look bad, should I just wait until I winterize to change it? I'll probably only go our 2/3 more times. Or change it now? If I only use it 2/3 more times with new oil, should I still change when I winterize?
BillK2632
Well-Known Member
You could just wait since you are only using it a few more times - just monitor it. If you do change it, I would not worry about changing it again at the end of the season. Also, check the crankcase ventilation - boat's don't usually have a PCV valve like a car, but they do have a hose that runs from the valve cover to the intake (carburetor in your case) - make sure that is clean and not clogged. Crankcase ventilation problems can cause some of what you are seeing around your oil fill. Main thing is if you see it turning milky or the level rises you have a problem.
- Apr 26, 2009
- 5,807
- Boat Info
- '97 330 Sundancer, Raymarine C80 suite with radar, Mercury 310 Hypalon w/8hp Yammie 2stk
- Engines
- 2X 454 carbs w/ vDrives
Others are glossing over the cracked block issue. You need to figure out where the block cracked and why. There is no good reason why a block would be cracked. It doesn’t happen routinely. It is very possible it is cracked internally and water could be getting in the oil. Sellers often lie about the problems. That oil looks fresh. If I was trying to lie to a buyer about a cracked block I would change the oil and say I had not run it in a long time. That way if or when you came back to me saying the oil went milky and the block is cracked I would tell you I had no idea. I have not run it in years. I would run it for as long as you can this year and then carefully check the drained oil for water. Check the oil also right away after a long hot run. Milky oil can settle out if you let it cool.
Handsome Transom
Active Member
- Jan 26, 2018
- 563
- Boat Info
- 1989 SeaRay Sundancer 268 454 Bravo
- Engines
- 454 Mercruiser bravo drive
Yes for running it and then checking the oil I would actually run it up to operating temperature though not long past that and change the oil .Now run it at idle for 5 min. This will let you examine the oil. . If it is in fact milky with water contamination at least you will have removed the water. Next time to dig I and find out if it is a cracked block or a head gasket.a head gasket is pretty likely if you've ever had an overheat condition and could be the source of oil in your bilge as well. You dont mention your temps when running what is that.?
That doesn’t look like milk from a cracked block you know that for sure and your level would be high. The valve cover whiteness is typical if it doesn’t get used or get used for short runs. If your really worried change the oil and keep an eye one it.
Oil in bilge can also come from outdrive I let seal check that level, trim and ps pump and lines
Oil in bilge can also come from outdrive I let seal check that level, trim and ps pump and lines
