Leaking vacuum valve vent on Volvo Penta

[LadyJessie]

My vacuum valve vent in the cooling system is leaking on my Volvo Penta MD2040. Is this a problem? I don't even know what this valve is doing as the Volvo manual is very silent on this point and even more silent on problems. The valve is not leaking much, only about ten drops per engine hour but that is enough to have created green corrosion on the valve and nuts. Is this a problem, and what should I do about it? Should I worry?

 

[VicS]

Hopefully This is a diagram of the valve and list of parts.

The diaphragm is not closing properly. You should with luck be able to dismantle it and clean it and/or replace any defective bits. Fingers crossed that it just needs cleaning. At least while it is leaking you know it is going to break the syphon when the engine is stopped.

There is I notice a repair kit

You could if you wish remove the diaphragm and route the water that is discharged to somewhere visible. That way you always know that it is not blocked.

 

[Dipper]

I have one on my Volvo 2001 and it also drips. There was a thread here a few months ago and it appears that the Volvo ones do drip whereas other makes do not. You can get a service kit from Keypart if you are worried but it will still drip!

 

[oldestgit]

Remove the top nut with vent tube and you will find a tiny little disc about the size of an old farthing, rubber flapper covered, with a pin hole in the middle. As long as your engine is above water level and the exhaust outlet is also there is no point in having the unit at all and you can blank it off. Its only there to ensure no water is drawn back up as the engine is cooling down after use. Just ensure its as stated regarding water level.

The VP replacement disc I think is about £12.

Regards.... Peter

 

[ytd]

I replaced ours and the drip stopped for a few months. Now I just route the overflow pipe into a 2l soft drink bottle which I empty every few months.

 

[LadyJessie]

Thanks for this advice. Now I understand this better and can sleep even more soundly. Great service!

 

[VicS]

[ QUOTE ]
can sleep even more soundly

[/ QUOTE ] Until some smart arse points out that if the thing blocks or fails to open it wont break the syphon and your exahust system will fiil with water which will also get into the engine and wreck it!

 

[LadyJessie]

Thanks VicS, that is an even better reason to ensure this thing is clean and open. Thanks again for the advice. I now think I understand what this mystery valve is supposed to do.

 

[Gypsy]

That's true Vic but the MkII sophisticated version of this water collector has the hose trapped in a hole in the screw-on top with only about 1cm going into the bottle and a hole in the side of the bottle about 3cm below the top for an over flow.

The MkIII version of this is to allow the water to dribble into a funnel type device and the bottom of the funnel led to a pipe which goes to a thru-hull. The funnel top must be open of course to allow air in if/when the line to the outlet is blocked.

The Volvo valve on mine is always dripping (which is a useful indicator that it is not blocked for its real purpose of letting air in) and I don't want it to gather in the bilge so that is how I cam to MkIII.

 

[VicS]

If you take a look at page 153 of the Vetus catalogue you will find that they do two versions of their air vent. One has a valve like the Volvo one. The other has no valve but has an overboard telltale which will give a visual indication that the cooling water pump is operating correctly, just like the "pee hole" does on an outboard engine, and will also break the syphon when the engine is stopped. Having no valve it is less likely to become blocked and obviously can't jam.

 

[Gypsy]

Thanks Vic, if my MKIII system fails I will check the Vetus options.

 

[Muddy13]

I replaced ours and the drip stopped for a few months. Now I just route the overflow pipe into a 2l soft drink bottle which I empty every few months.

Hi. In the manual for the Volvo 2002 it says to test the valve by sucking on the out vent when assembled - I'm guess that means that I should not be able to suck air out if the valve is working? Mine leaks badly - a drip a second - so I've ordered a new seal. The old one is wedged in so I can't get it out to examine without damaging the ring and seal.

 

[pvb]

Wow! Over 8 years. Almost a record.

 

[Tranona]

Wow! Over 8 years. Almost a record.

And the OP is unfortunately now deceased!

 

[spannerman]

The Volvo valves are junk, I have tried to repair many over the years and usually without success, the problem is salt crystals form under the disc and prevent it seating. My advice is throw it overboard and install a Vetus valve which is fit and forget.