2.5 Mercruiser with water in oil

Newbie here!Great site.Used this site to learn about my first boat,purchased last Oct,an 87 Invader I/O bowrider with 2.5 and Alpha 1 set up.When I got the boat it ran perfect so I just changed the oil,poured some Seafoam in the tank and had fun.Used the boat for fishing and short trips with the family.Always good oil pressure(30-40),ran cool(140-170)Used about twice a month since Oct.About a month ago,we got alot of rain.Didnt use boat for a month.Boat sat in the rain without mooring cover.Last week,launched it and no start.Weird..it always started right up.My buddy automatically said"points"and I agreed.So...replaced points,wires,cap,condenser,plugs....and then I decided to check the oil before start up...WATER!!Milkshake looking oil!!So drained the oil and replaced with new.Started engine.Fired right up.No noise,no miss,good oil pressure,running cool......Shut it down and checked oil...milky???Oil level not rising on muffs...I really dont believe the block or head is cracked.Never overheated,has good oil pressure,hasnt froze lately.HELP!!What now??

Re: 2.5 Mercruiser with water in oil

Gonna take a couple of oil changes to rid the rain water from the crankcase. Just watch the full line on dip stick and make sure its not rising.

Re: 2.5 Mercruiser with water in oil

If the engine cover was over it , it would be hard pressed for that much water to get into the engine If the engine cover was off and the oil filler cap off , that would yield about a couple of table spoons of water in the engine . That amount of water could evaporate through normal usage . I hope the moisture clears up for you but I would plan on the worst as these engines are under a great load at all times and sometimes fail

Re: 2.5 Mercruiser with water in oil

Welcome to iBoats . . .

Next steps are compression test and cylinder leak test . . . maybe even a cooling system pressure test.

Hopefully those things will tell the story.

Re: 2.5 Mercruiser with water in oil

Thanks guys....This weekend I plan to run some test and change the oil and filter....again.Will report back soon

Re: 2.5 Mercruiser with water in oil

Takes an extremely small amount of water to make the oil milky. You may have to change it a few times to get rid of it.

Re: 2.5 Mercruiser with water in oil

I am hoping its just moisture/rain water....UPDATE!!!Found a small oil leak coming out where exhaust usually come out.Right below the big boot,leaking on where outdrive pivots???Will run compression test in the morning and still trying to figure out how Im gonna pressurize the cooling system.I love this boat.I want it to be right.Im gearing up for the worst.A total rebuilt,but wanna save it if I can.

Re: 2.5 Mercruiser with water in oil

You will need to make a determination if it is engine oil or gear oil . Gear oil will have a stronger smell to it I would doubt if engine oil can make it back that from from the engine . maybe post a picture of the offending area

Re: 2.5 Mercruiser with water in oil

the manifolds can leak internally and back feed into the exhaust ports into the cylinder and past the rings and then to the sump.have you checked for any rust on the sparkplugs and a compression test looks inevitable