496 HO - Mercruiser with antifreeze in crankcase
 

I have a stock 2003 Mercruiser 496 HO with a bravo1 drive. It has the closed cooling system. The antifreeze level dropped and now it is in the crankcase with the oil. I attempted to refill the cooling system but the water ran quickly to the crankcase. I pumped out the crankcase and replaced the oil and filter. Then I pulled the plugs and added water again to the cooling system and rolled over the engine to see if water would shoot out the spark plug holes. No water shot out the spark plug holes. What can I do next to determine the issue. Is there something else besides the head gasket. that can cause this leak into the crakcase? What steps should I take next?

Dex-Cool and oil don't mix well!
 

What part of the country are you in and how was the winter layup done? If it freezes in your area. sounds like you could have a cracked oil cooler,cracked block, head or a head gasket that is leaking into the lifter valley. Sounds like the engine will have to come apart to repair whatever you find unless its the oil coole., DO NOT run the engine with the dex-cool coolant in the oil as it will wipe out the bearings and such very quickly. You can take the oil cooler out fairly easily and have it pressure checked with air. sometimes raw water is left in the cooler during winter layup and if it freezes there it will crack the cooler and water can get into the oil, but not dex-cool coolant from the closed cooling system. Hope its not to bad. If you need assistance with a new 496 short or long block, we have them in stock, so call if we can help.

Best of luck and best Regards,
Ray @ Raylar

Pull engine, disassemble, and inspect. Sounds like cracked block.

Wannabe

Oil cooler leak wont put antifreeze into the oil pan. Freeze damage, head gasket.

Add intake gasket to list of things to check. More likely than head gasket. You will see the intake gasket before anything of the other causes as the motor comes apart.

Like the others said, did it freeze??

Wouldn't it if the oil cooler leaks water into the oil cooler?

The only way the block could freeze is that it never had the correct dilution of anti-freeze or it just had water.

Isn't it a closed system?

Ken

mrfixxall
 

intake manifold gaskets? if antifreeze flow through it.,,will leak into the lifter vally,or your oil cooler is cracked from being frozen or might be the front timing cover,dont remember if its all one unit with a waterpump built into it...

Is the oil cooler on a 496 cooled by engine coolant or raw water??

mrfixxall
 

raw water,usually if they freeze and brake they will also leak antifreeze out the water pickup of the outdrive too!