7.4 L Volvo Penta turned into a milkshake - what to tell the mechanic

[vetting]

Have a buddy with a 7.4 L Volvo Penta (GEN6 GM Marine block. 7.4 liter, 454ci)
that made a major oil/water milkshake on the way back to the slip last week. The breather hoses that route back into the flame arrester puked the milkshake over the top of the block. The water was never just sitting in the motor so it was at least "frothy" oil/water mix. I know that isnt the ideal lubrication situation, but they are trying to tell him that bearings/rings/crank are all going to have a bunch of issues in the future. Personally I think it is salvageable (since it wasnt run that long) if its just a riser, intake gasket, cracked head, or head gasket. I cant imagine that its a cracked block/winterization issue since multiple trips were run on the boat this year.

Any suggestions on how to proceed?

 

[cyclops222]

A honest, very experienced, mechanic is all that is required..

 

[flashback]

It doesn't take long for that mess to get circulated and rust things and if it's coming out of the valve cover breather tubes you can be sure it's everywhere.

 

[vetting]

It doesn't take long for that mess to get circulated and rust things and if it's coming out of the valve cover breather tubes you can be sure it's everywhere.

I milkshaked a Mecruiser that filled then entire engine due to a cracked head. Replaced the head and cleaned everything. Entire inside was spotless without rust.

I am just trying to figure out what the appropriate steps are and potential causes.
Have a compression test done and/or pressure test the raw water cooling side.

 

[Scott Danforth]

Pull the motor and go through it.

How was the boat winterized?

 

[tpenfield]

It depends on how the engine made the milkshake. If it was from a crack in the block, then it would not be worth fixing IMO.

It should not be allowed to sit for long, better get the water leak diagnosed and resolved. The motor may need to come out of the boat.

 

[vetting]

It was winterized by a boat yard so I assume drain and fill.
I agree, if the block is cracked its not worth it. Anything else, I would go with a repair.

 

[Donald0039]

Pull the engine. Tear it apart. First figure out how the water got in and then examine the bearings and journals for damage. They should look pristine. Hopefully you will find an exhaust manifold. And not a cracked block. Were you boating in fresh or salt water? Is the engine FWC or RWC?

 

[Scott Danforth]

It was winterized by a boat yard so I assume drain and fill.
I agree, if the block is cracked its not worth it. Anything else, I would go with a repair.

A running used long block from a u-pull-it is only $350.

A reman is about $3k from your local machine shop

That is cheaper than the other repairs.

 

[Donald0039]

A running used long block from a u-pull-it is only $350.

A reman is about $3k from your local machine shop

That is cheaper than the other repairs.

The u-pull-it places have marine engines or a car or truck engine you would need to make into a marine engine. I think the cam is different and the mains are 4 bolt mains. I thank that kind of engine is only viable if you can do all the work yourself.

 

[Scott06]

The u-pull-it places have marine engines or a car or truck engine you would need to make into a marine engine. I think the cam is different and the mains are 4 bolt mains. I thank that kind of engine is only viable if you can do all the work yourself.

The 4 bolt mains is a myth in most cases. Marine engine is essentially the same as a truck engine cam is similar to truck cam, swap head gaskets core plugs marine circ pump and go

You said it was winterized by marine shop you should start there it is likely what you mention that winterization was not done right and they should be on the hook for repairs.

As mentioned pressure test coolant system likely the only way this happened. My neighbor used his boat for a month before crack opened up and filled crank case

 

[Scott Danforth]

The u-pull-it places have marine engines or a car or truck engine you would need to make into a marine engine. I think the cam is different and the mains are 4 bolt mains. I thank that kind of engine is only viable if you can do all the work yourself.

Truck cam is close enough. The truck block is exact same L29 4-bolt block in the OPs boat. All Gen V and VI motors are 4-bolt. Core plugs and circulation pump are all that is needed because the trucks even got the MLS head gaskets

 

[cyclops222]

All of the machined surfaces look very good in the picture.

 

[Donald0039]

Truck cam is close enough. The truck block is exact same L29 4-bolt block in the OPs boat. All Gen V and VI motors are 4-bolt. Core plugs and circulation pump are all that is needed because the trucks even got the MLS head gaskets

Looks like a hot tanked engine.

 

[Donald0039]

I have watched some YT from Dave's Auto. He has a big repair and machine shop in Utah. He has a SIM tester where he can put an engine on and turn over the engine at various speeds to test it out before spending the time to install the engine.

 

[Scott Danforth]

Looks like a hot tanked engine.

Dude, that is a picture of my Gen VI motor after the machine shop. I posted it to prove all Gen VI motors are 4-bolt