volvo penta MD5C on etap 26

[smiala]

Hi,

as a newcomer to engines can anyone pls explain a part for me ?

The coolant on this engine enters via the prop leg, then via the pump to a device I think called a syphon, then into the engine. Given some idiot (me) has taken this to bits to clean it and then lost the inards, I wondered what it did for the engine.


As the exhaust outlet is below the water line, the air intake is well above, I would welcome any views on this device, before I need to raise the mortgage for a volvo spare....

thanksalot,

 

[Will_M]

Vacuum valve / air vent / anti-syphon valve.....

Call em what you will, but the idea behind them is. If a boats engine installation is at or bellow the water line a vacuum valve should be installed. This valve prevents siphonage occurring through the sea water intake, resulting in water ingress into the engine.

Typically fitted a suitable height after the sea water pump, but before cooling water 'enters' engine so to speak.

If yours is an original Volvo Penta vacuum valve, then when you took it apart you would have found a small (very small) rubber valve type arrangement. You can buy this as a repair kit from a VP dealer pn.875738 @ £2.93

TBH your better off changing the valve, if its a VP cast brass type, change it for one of the Vetus units, these are far more efficient. They have two types, one which has a ventilation line the other, similar to the VP style, does not.

Think your find the Vetus types retail around the £55'ish mark. Any chandlery worth their salt will be know the Vetus products.

 

[starboard]

Agree with "Funsize" I have an MD5b, now 25 years young and still doing its job. Give it a little TLC and it will look after you. Should major problems occur however spares prices will mean a new engine the cheaper option.

Fair tides

Paul.