Leaking engine oil out of boat into water

[Nnewman2]

Hey everyone. First post here. Hoping to find some answers.

Loss of oil in my 08 crown line with 4.3 mercruiser. Confirmed engine oil is going out of the boat, Not into the bilge. It’s not drive lube, it’s engine oil. Added 3+quarts after it abruptly lost all oil pressure and dipstick showed zero.

What’s the consensus here? Is this going to be a water jacket/block internal crack issue automatically since the oil is going out of the boat?

I’m also hearing that Headers could be culprit and to check spark plugs but the engine is not smoking and it runs perfectly as long as I have proper oil levels maintained. Oil is not milky when checking dipstick.

I’m trying to determine if longblock is only option or not. Thanks in advance.

 

[Scott Danforth]

first, stop using the boat. then pressure test your block/heads

most likely you had an over-heat and damaged the head gasket or warped a head

do you have an oil cooler (not standard on a 4.3)?

 

[Nnewman2]

thanks scott. Shut it down immed when I saw oil pressure drop. Had it towed back. Didn’t try and restart until filled up with straight 40. No metal shavings in oil so pressuI saved bearings and such.

never had an overheating issue to my knowledge.

Do I need to find a machine shop to do a pressure test on block and heads to determine extent of internal leak?

I pulled the oil pressure sensor and put pressure gauge on it and had good pressure holding steady there.

no oil cooler

 

[Scott Danforth]

you can pressure test the cooling system yourself.

is this a new to you boat?
is the motor EFI?
got a serial number so we can look up if it has an oil cooler?

or better yet, you look to see if you have an oil cooler. if the oil cooler failed, it will pump oil into the raw water stream.