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Mercruiser 165 Chevy 250 6 cylinder, water contamination

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merc165

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Have inherited a ski boat that started off running well then I noticed that the oil was contaminated with water only revs to about 3.8k. I've had the head reconditioned and pressure tested, reinstalled with new head gasket and head torqued to spec, all good. Took the boat for a test run revs to about 5k RPM sounds good, no missing, loads of power. Removed the engine cover to inspect for leaks and saw loads of milky oil spewing out all over the place. Could a cracked inlet manifold congest this amount of water. What else must I look for?
 
merc165 said:
Have inherited a ski boat that started off running well then I noticed that the oil was contaminated with water only revs to about 3.8k. I've had the head reconditioned and pressure tested, reinstalled with new head gasket and head torqued to spec, all good. Took the boat for a test run revs to about 5k RPM sounds good, no missing, loads of power. Removed the engine cover to inspect for leaks and saw loads of milky oil spewing out all over the place. Could a cracked inlet manifold congest this amount of water. What else must I look for?
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yes those manifolds typically crack when the engine gets overheated and the manifold doesn't get enough water, sad.

There was a Fix to help prevent this from happening and can be done with a short trip to the hard ware store.

What you'll need to look up is the Reverse Water Cooling Setup for an Inline 6. See this Thread.
http://forums.iboats.com/mercruiser...-manifold-my-i6-165hpmercruiser-261607-2.html

Basically you would get an end cap for the AFT like what is installed on the Front only turn it to port or starboard and have the Water from the thermostat housing go in there.. then water fills up back to front comes out the front then goes into the Exhaust Elbow of which you would have to BLock Off the Elbow ( Dry Exhaust ) which there is a fitting you can remove to put in a pipe fitting elbow.. then done..

but yes they crack, and I had one crack while I was underway. good luck.
 
Could a cracked inlet manifold congest this amount of water.? If the engine was taking in water from the Intake/Exhaust Manifold it would miss fire, so, yea it looks like you might have a bad head or head gasket, pull the spark plugs to and to a compression test you might even have a Cracked Cylinder.
 
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