Water damage to exhaust valves - How?

[checkyourmirrors]

I've got 256 hours on my Volvo 5.0L MPI engine and after getting some poor compression tests and pulling the heads. There is water damage (such as pitting) to the heads, valve seats and tuliping on one valve. The mechanic checked the riser/elbows and see no water entry and are unsure as to how this might have happened.

Since I'd really like to avoid this in the future, does anyone have any thoughts as to what could have caused this or how to avoid?

 

[Big Boat Bay Buster]

Re: Water damage to exhaust valves - How?

What year is your engine? I had an '87 5.7L. GM did lighten up the head castings around this time to save weight. Both my heads had cracks across the exhaust valves in the middle cylinders. The cracks extended to the water jackets and water was getting into the cylinders. That was my experience.
Chris

 

[Silvertip]

Re: Water damage to exhaust valves - How?

Water injestion can occur in a number of ways. Through risers, bad gaskets, leaky head gaskets, unsealed head bolts that pass into water jackets, and head and block cracks due to overheating or if you live in an area where temps get below freezing.

 

[Apollo75]

Re: Water damage to exhaust valves - How?

Well, in my opinion if you got pitting and other damage in the cylinder head / combustion chamber ---> that is detonation ---> that much water would make an engine run rough and if it came through the fuel filter it would miss / sputter.

There used to be --- probably still sell them --- a jug of water you added some red stuff to ---> made it pretty I guess ---> It injected water vapor into the engine ---> I have taken those engines apart and the piston tops and combustion chamber looked like new, clean with no carbon deposits at all

Don Prudhomme would say cool humid air makes more horsepower too

Salt ? I will bow out to the Marine Mechanics.


OFM


___________________________________
"If the boat is not sinking or on fire ---- Relax."

 

[Maclin]

Re: Water damage to exhaust valves - How?

Sounds like a heat issue from a combination of lugging and detonation maybe...What do the spark plugs look like? Were the pistons extra shiny?

 

[Bondo]

Re: Water damage to exhaust valves - How?

There is water damage (such as pitting) to the heads, valve seats and tuliping on one valve.

Ayuh,.... Detonation was My 1st thought, but Apollo,+ Maclin covered that,...
Another possibility is the fact that Volvo decided they don't need Exhaust Shutters,...
Water splashing back is very Possible... Especially when the throttle is chopped... I won't run a boat without them...
And,...
Depending on your Hull,... I've read about Volvo,+ Merc both having Issues when the boatbuilders put the motor to Low in the hull...
You need a Minimum of 13" from the outside waterline to the downturn of the risers...

 

[smithrock]

Re: Water damage to exhaust valves - How?

Ayuh,.... Detonation was My 1st thought, but Apollo,+ Maclin covered that,...
Another possibility is the fact that Volvo decided they don't need Exhaust Shutters,...
Water splashing back is very Possible... Especially when the throttle is chopped... I won't run a boat without them...
And,...
Depending on your Hull,... I've read about Volvo,+ Merc both having Issues when the boatbuilders put the motor to Low in the hull...
You need a Minimum of 13" from the outside waterline to the downturn of the risers...

Is it possible to get water to get water in the engine through the exhaust from driving in reverse to fast?

 

[Maclin]

Re: Water damage to exhaust valves - How?

"Is it possible to get water to get water in the engine through the exhaust from driving in reverse to fast?"

Not if the engine is running, and stays running a few seconds after the backing is complete. If you back real fast and turn it off at speed then that is asking for trouble.

 

[jtybt]

Re: Water damage to exhaust valves - How?

Some marine engines are more prone to water reversion. That's the sucking back of water from the end of the riser where the raw water is mixed with the exhaust.