Volvo penta broken exhaust valve

[capton1]

I have a volvo penta 5.7gsi with a broken exgaust valve and distorted intake valve, resulting in a hole in piston
any ideas on cause ?

 

[0352Marine]

Re: Volvo penta broken exhaust valve

There too many factors that would cause this. Over reved is the most likely causing the valve to "float", but it could be the wrong fuel, timing chain broke, valve spring broke these are common problems with 350 when oil is not chaged on a regular basis etc etc

 

[Bondo]

Re: Volvo penta broken exhaust valve

I have a volvo penta 5.7gsi with a broken exgaust valve and distorted intake valve, resulting in a hole in piston
any ideas on cause ?

Ayuh,... More than likely, it went Lean from Bad fuel, or crud in the fuel, 'n Detonated the motor to death...

 

[Maclin]

Re: Volvo penta broken exhaust valve

If you want more then post some pics and some more details. The order things happened in would give more clues, like if the piston melted and holed first that is detonation, pic of the piston could help tell. If the Intake is tuliped and that is what you mean by distorted then that could be due to lugging. Broken exhaust valve, like where, at top of stem, or bottom, did it freeze in the guide then the piston hit it and that is reason for the holey piston, etc.. Did it happen at higher RPM or at startup, what was most recent service if any, crap like that.

 

[capton1]

Re: Volvo penta broken exhaust valve

Valve spring was good, valve broke at stem base, customer states he was running along, then pulled back and thinks water entered back thru exhaust, causing hydrolock (Nah)
more inspection to follow, timing chain, high rpm, etc. will let you know as I continue inspection Thanks

 

[Scott Danforth]

Re: Volvo penta broken exhaust valve

hydrolock will shorten the connecting rod prior to damaging valves (dont ask how I know)

my first thoughts are:
detonation
something higher than E10 for ethanol
running lean
bad valve from factory

 

[capton1]

Re: Volvo penta broken exhaust valve

Turns out, thermostat not opening at 160, looks like the culprit so far
Thanks