Water Intrusion

[gegenator150]

Greetings all,

I recently bought a gem of a boat with only 192 hours on the Mercruiser 3.0 from the original owner. The engine runs great and has excellent compression on all four cylinders.

I've never had this boat on the water. It had sat for many years but was told it was winterized. The fellow is a real stand-up guy and I don't doubt him, but after getting it running, I'm having some issues.

It pours oil out the back of the boat through the exhaust. Oil in water, water in oil, etc. I removed the riser and elbow to inspect, and you can see water intrusion in the intake side of the engine. The exhaust ports are dry. Despite having excellent PSI on the engine, am I looking at a cracked head or head gasket? I just can't see how a cracked riser or associated gaskets could allow water to get to the intake side since running water through those riser ports only allowed water through the exhaust side. And yet... oil would come pouring out the exhaust back by the gimbal ring when the boat was running.

Owned and restored many cars... but the water system on a boat is new to me! I've been reading through the stickies on the site- very helpful info. Haven't been able to find anything yet (that I know of) for my particular situation. Thank you for your help!

~Tom

 

[Scott Danforth]

first, welcome aboard

the pictures call in doubt how much of a stand-up guy the prior owner is

the exhaust ports show that the exhaust manifold is either cracked from freezing or the manifold to elbow gasket had failed. Rust in the exhaust ports is bad...... PERIOD

is this a salt water boat? or a fresh water boat.

if its a salt water boat, the exhaust manifold went well beyond its expected life in salt water.

if its fresh water, most likely the block cracked (inside just above the pan rail). this would be a freeze crack. this would lead to oil in the exhaust.

pull the contents of the oil pan, I bet there is water in there.

drain all the water out of the block (drain is in the lower right of your picture). you should then be able to block off the hose from the transom shield and the hose to the exhaust manifold and pressurize the block water jacket to 15 PSI, and it should hold 15psi forever. just like pressurizing a radiator system.

 

[gegenator150]

Thank you Scott. I believe this has always been a fresh water boat.

I've changed the oil since getting it running (this was several weeks ago) then discovered the mixing issue. I actually bought another engine just in case this one was bad. Sadly, the boat had a rotten Fram oil filter on it when I got it... which might tell me there was water sitting in the oil filter for a long time. It's just a shame since it runs so well. Hopefully the "new" Facebook Marketplace motor is decent!

 

[Scott Danforth]

Just make sure to match generations of 3.0

The 1990 and below is slightly different than the 1991-2014

 

[Bt Doctur]

everyone is pointing to the exaust when the ports in question are intake ports in the head. support the manifold and fill with water see if it runs out from the intake ports of the manifold