A Recent Marine Survey / Engine Survey in Fort Lauderdale of a Volvo-Penta Engine

[SuenosAzules]

I recently conducted a marine survey and engine survey in Fort Lauderdale and thought I would share this. During the sea trial there was some diminished performance of the engine when attempting to reach WOT. The single engine in the boat was a 2006 Volvo-Penta Gi 8.1 Liter, eight cylinder 375 HP inboard gasoline marine engine. Cylinder number four had low compression (about 140 psi compared to 180 psi on the other cylinders). Inspection of the spark plug on cylinder number four showed corrosion and some water exposure on the electrode compared to the other spark plugs. Borescope photos of cylinder number four showed salt and corrosion in the cylinder and on the piston. A oil sample analysis was taken and revealed that there was sodium in the oil. This was most likely caused from a worn gasket from the engine manifold where water leaked into the exhaust port and down into the cylinder causing the corrosion and salt deposits in that clylinder. Low compression is most likely from the corroding piston or a stuck piston ring.

If you find in your own boat that there is some diminished performance, my advice is to check for any fuel contamination at the fuel / water separator filter. If that appears to be okay, then check the spark plugs. If you see one of them to be fouled compared to the others, conduct a compression check on all of the cylinders. If that cylinder is less than 10% lower in compression compared to the other cylinders and corrosion is evident, check the gasket at the exhaust manifold. The gasket wears away over time allowing water to get into the exhaust ports causing water intrusion into the cylinders. Just thought I would share this for those interested. The phtotos of what I found are below:

[tuffr2]

Do you think that is a common issue with that engine? There has to be a ton of those engines out there as they are very common. Do you think Mercruiser is any better. I knife prefer the Volvo.

I do not have a boat yet. I just sold my freshwater runabout. I am now looking at boats in the mid 2000's with I/O set-ups. The boats I am looking at will have either the 5.7 litre or the upgrade to the 8.1 litre.
There are a few 6.2 litres out there.

Did this boat have a closed cooling system?

[tuffr2]

How often have you seen this issue? I trying to gauge how common it is.

[old frog]

Search out information of the subject of water reversion. A known problem.

[tuffr2]

Ok...I have been reading up on this issue. I have owned motorboats since 1980. Both Outboard and I/O configurations. Always in fresh water and usually only 200 hours/year during boating season in the north. Boats were always on a trailer and removed from the lake when not being used.

I never heard of nor experienced this issue. I have boating buddies that they never had an issue either.

So I am trying to come to grips with my naivety. What I am reading makes sense. Humans historically have battled water...trying to keep it where they want. Either in something or keeping it out of something.

[old frog]

The (correctable) condition occurs under certain conditions & exhaust systems. Typically big blocks w/ aggressive cams. Exhaust layout may contribute. If your engines are experiencing this type condition, an (V-8) experienced gasoline marine mechanic should be able to assist.