Application is a sailboat auxiliary with SailDrive; raw water intake on SailDrive flange.
Apparent blown head gasket, but not yet disassembled to verify presence or not of casting cracks. An initial violent overheat, with loss of coolant, now runs without overheating with system de-pressurized. No pressure gauges.
There is elevated sodium in the oil sample, and apparent small coolant quantities in the oil (closed system temporarily running water due to system pressurization and vomiting - expansion tank cap has to be left loose) .
Word on the docks has it that turbo housing may be closed system cooled, and that a certain unspecified turbo seal or gasket failure can cause coolant to enter crankcase via turbo oil drain.
The aftercooler has no plumbing return for coolant, so why Volvo would cool the turbo housing and make the return path for it's coolant essentially do a "U" doesn't make sense on the surface.
Does any one know how much credence to give the dock talk about turbo gaskets/seals as a possible cause or a contributing factor?
Does any one know if such a turbo gasket/seal were to leak coolant, if there is any logic to turbo not exhibiting other symptoms of distress or noise?
Could coolant be forced through the intake and create a mild hydrostatic lock condition that would not clearly damage the piston or con rod, yet precipitate the head gasket to pop?
The relatively generic Volvo Workshop Manual and Owner's Manual have no illuminating text, or line drawings suggesting a cooled turbo, but word is some do, and some don't.
Thanks for your consideration.
George Little
Apparent blown head gasket, but not yet disassembled to verify presence or not of casting cracks. An initial violent overheat, with loss of coolant, now runs without overheating with system de-pressurized. No pressure gauges.
There is elevated sodium in the oil sample, and apparent small coolant quantities in the oil (closed system temporarily running water due to system pressurization and vomiting - expansion tank cap has to be left loose) .
Word on the docks has it that turbo housing may be closed system cooled, and that a certain unspecified turbo seal or gasket failure can cause coolant to enter crankcase via turbo oil drain.
The aftercooler has no plumbing return for coolant, so why Volvo would cool the turbo housing and make the return path for it's coolant essentially do a "U" doesn't make sense on the surface.
Does any one know how much credence to give the dock talk about turbo gaskets/seals as a possible cause or a contributing factor?
Does any one know if such a turbo gasket/seal were to leak coolant, if there is any logic to turbo not exhibiting other symptoms of distress or noise?
Could coolant be forced through the intake and create a mild hydrostatic lock condition that would not clearly damage the piston or con rod, yet precipitate the head gasket to pop?
The relatively generic Volvo Workshop Manual and Owner's Manual have no illuminating text, or line drawings suggesting a cooled turbo, but word is some do, and some don't.
Thanks for your consideration.
George Little