Check Valve, leaking air out

[cmyers_uk]

Volvo Penta 4.3GL PEFS (2000). There are two valves one in each exhaust elbow with an open pipe that terminates by the flame arrestor. I have been told they are also called siphon valves. One valve has started letting air out from the Elbow. When I stop the engine I can hear it burbling , and its spits some water, other side is fine. Is this likely to be just the valve gone or is it an indication of more serious problems?<br /><br />Thanks<br /><br />Chris

 

[BRIAN03]

Re: Check Valve, leaking air out

Volvo Penta calls those pulse tubes. They go into the middle of the riser/exhaust side of riser. They were put there to help with reversation on the 4.3 roller cam engines. If you look at the first air pumps on cars/trucks they had them on the exhaust manifolds. It was a good though on paper but they didnt work so Volvo Penta raised the static line from 9.0 inches to 13.5 inches.

 

[cmyers_uk]

Re: Check Valve, leaking air out

Brian,<br /><br />Sorry to be a bit slow but re<br /><br />"They were put there to help with reversation on the 4.3 roller cam engines."<br /><br />I dont really understand what you mean. Do you mean reversing the boat? Again static line what does that mean?<br /><br />Lastly should air be released from them or should they just suck air in. <br /><br />Thanks for your help , I am trying to learn but at the moment dont really understand what these bit do. I have brought the 3 Volvo Penta manuals but cant find them in any of them.<br /><br />Regards<br /><br />Chris

 

[vinney]

Re: Check Valve, leaking air out

Do a search on reversation and static line on this forum. Hit the red Search. If you need more help I will glad to help.

 

[cmyers_uk]

Re: Check Valve, leaking air out

Vinney, Thanks for the tips I have read your posts with interest and thibnk I have a handle on static line and reversation. I now understand why the valves are there, not how they work though. Could you tell me if they should let air out of the elbow or only let air in. The problem I have is that on one side the valve is quiet on the other side when I turn the engine off the valve continues to let out air. I assume the valve is broken and will swap them to see if the symptoms follow the valve. But it would be nice to know what test I should do. I have brought the proper Volvo shop manuals but cant find reference to them.<br /><br />Regards<br /><br />Chris

 

[cmyers_uk]

Re: Check Valve, leaking air out

Vinney,<br /><br />Perhaps I can answer my own question but if you could confirm if this is right I would be grateful. <br /><br />my understanding <br /><br />The purpose of the valve is let air into the riser to combat the pull caused by the exhaust valve not being closed as the piston starts drawing air in, hopefully stopping water being sucked into the engine. The valve shouldnt let air out of it as that would be letting exhaust gas into the engine compartment. <br /><br />Regards<br /><br />Chris

 

[vinney]

Re: Check Valve, leaking air out

They were put on the engine to help take some of the pulse that is created at idle with the roller cam in that engine. As the engine pulses the check valves release and try to help decrease the pull in the exhaust on the compression stroke. There should be no air leaking out of the pulse valves. The valve/check valves rust and they don't seat properly. If you have 13.5 inches of static line on this boat with the normal amount of load in the boat. You can remove the pulse tubes and plug the hole in the risers. Run hoses from the top of the valve cover to the spark arrestor. As you have found out by looking they don't use the pulse tubes any more.

 

[cmyers_uk]

Re: Check Valve, leaking air out

Vinney,<br /><br />Thank you for the explanation I will check the static line with my normal load. I have ordered the valve as you say the middle is all rusted, got a shock as in US its $15 in the UK its $85. I have checked the assembly diagrams and the next years model has a plug instead of a valve so I know for next time.<br /><br />Thanks again BRAIN03 and vinney.<br /><br />Chris