I havea 350 mercury boat engine, over the winter it got water in the oil.but the block is not cracked.?

Question

If i drain it and refill it a few times to flush out the old oil would it be ok.

Answer 1

the risers may have had water in them if you did not drain the engine . may have frozen the exhaust pipe in the riser and allowed water into an open exhaust valve. you have a major repair if water is in the pistons.

Answer 2

Yes, that's what you need to do!  But, I also suggest that you add an oil treatment on the last couple tries.  I've had this happen afew times over the years, and the engines ran for years.  Good luck!  

Answer 3

If the block's not cracked, where did the water come from?  Drain(not pump out) the oil, change oil and filter, and run the boat for awhile, then check for water.  Condensation is not the culprit, 25 years as a marine tech in  a harsh climate (CAN), and i have never seen condensation build up enough to even "streak" the oil.

Answer 4

Did you winterize your motor before it got freezing weather? Because if you have water in the oil pan that means that the block is cracked somewhere. The block will have to be replaced, sorry about the bad luck.