Water in oil on a 79 OMC 140

I had just bought a 79 Crestliner with a OMC 140 and I have noticed when I run the engine wide open on the water, I am ok, but when I stop and kill the motor, then start it back up after awhile, I get water filling the crankcase. Normally if will fill about a quart over or so. I have a end plate cap on the front of the exhaust manifold, which has the water inlet coming from the water pump, on the bottom side right where the bolt goes that ear is cracked and seperated all the way across, which when the motor is running will leak water, is it possible to get water in the oil through this? This is my first boat, and I know nothing on them. Thanks for the help in advance!!

Re: Water in oil on a 79 OMC 140

I suppose that your cracked end plate cap on the manifold could be a place where water could move from the manifold water jackets to the exhaust runner, and from there drain down to the head, through the exhaust valves and into the block.

A much more common scenario is that the engine doesn't get drained of water before winter, freezes, and cracks the water jackets in the block somewhere allowing water to enter the crankcase.

You will have to find out where the water is coming from and get it fixed before you go out again. The pistons will seize and you will have a very expensive repair.

Here is a good place to get started, it is from the "Adults Only" sticky post at the top of this forum.

http://forums.iboats.com/showthread.php?t=369864

Re: Water in oil on a 79 OMC 140

Thanks Sean, I just replaced the end cap and gasket, going to hit the water this weekend to see if it fixes it, I know over winter a freeze plug popped out, which is now replaced, so I am hoping I don't have a crack in the block, I don't believe I do, the motor runs great, and I figure it would run like garbage with a crack. I changed the oil, put some good thick stuff in, will see what happens. But thank you for getting back to my post!!

Re: Water in oil on a 79 OMC 140

The 140 4cyl is a great block for cracking externally rather than internally.

Manifolds however will crack / rot inside as wass as outside. More likely a bad manifold.

I recommend pulling it, and fill water jacket with water. If it leaks to the intake / exhaust runners, it is junk.