Mercruiser 5.7 260hp Milky oil. Ideas??

[CaptainHook]

Just curious, I was told by a mechanic that this particular motor has bad risers and these are leaking water back into the cylinders, and that water is getting into the oil???

Doesn't sound right to me.

This motor does not have an oil cooler, sooooo head gasket or craked block????

By the way, it still is running perfect.

 

[bruceb58]

Re: Mercruiser 5.7 260hp Milky oil. Ideas??

Is your oil level still pretty constant? If so, it could be the risers. How old are they? You use this in salt water?

 

[CaptainHook]

Re: Mercruiser 5.7 260hp Milky oil. Ideas??

I ran it on the hose today for about 30 mins and the oil level did not go up.

I just was having a hard time believing that much water could leak into the cylinders and then make it passed the rings as well.....

Not salt water, about 15 yrs old, and not sure if it is a sign of anything but on both sides at the riser/manifold gasket, there is a lot of rust and some slight leakage as well.

 

[bruceb58]

Re: Mercruiser 5.7 260hp Milky oil. Ideas??

It can happen. Doesn't take much to make the oil milky.

I ran it on the hose today for about 30 mins and the oil level did not go up.

If its a slight crack internally, that still may not be enough to raise the level. Are you in an area that freezes? Has the bilge ever filled with water up to the crankshaft level?

 

[CaptainHook]

Re: Mercruiser 5.7 260hp Milky oil. Ideas??

Yeah, it freezes here, the boat was professionally winterized but we got 5 feet of snow this winter. I wonder if the blige filled, then froze around the motor.....

 

[bruceb58]

Re: Mercruiser 5.7 260hp Milky oil. Ideas??

Might be time to pressure test the cooling system.

 

[Ocean Airbrush]

Re: Mercruiser 5.7 260hp Milky oil. Ideas??

Same thing happened to my 4.3. Replaced the riser and manifolds and problem solved.
Better get them fixed quick though, the water coming in can make you drop a valve or other major head damage.

 

[CaptainHook]

Re: Mercruiser 5.7 260hp Milky oil. Ideas??

I will be pulling the risers this weekend to have a look at their internal condition.

 

[bruceb58]

Re: Mercruiser 5.7 260hp Milky oil. Ideas??

Make sure you replace with mercruiser gaskets.

 

[Jbird4]

Re: Mercruiser 5.7 260hp Milky oil. Ideas??

I wonder how things turned out, I have the same problem.

 

[turbofan]

Re: Mercruiser 5.7 260hp Milky oil. Ideas??

I have encountered a similar problem. After a attempting to start the engine there was no rotation, after 10 days since last running the engine, the engine is hydro-locked. I pulled the spark plugs on the right bank, cylinders 4 and 8 had water in them. Pulled the left bank spark plugs and cylinders 3 and 7 had water in them too. I syphoned out the oil to find a trace amount of water in the oil.

Feed back I have received is that the risers could be corroded or the gaskets broken. I have not removed the risers just yet to inspect them.

The Mercruiser service manual states that backwash through the exhaust is possible. Anything is possible but....

I operate in fresh water, sea water cooling system, propery winterized. But I am the third owner of this boat. I don't know if the engine was fogged properly before I bought it.

Prior to this attempt to start the boat ran perfectly, no over-heating, oil pressure is good. Performance is good.

I was wondering if anyone had heard of this happening or had it happen to them?



2000 Doral
230BR
5.7 Liter w/ Bravo 3 outdrive