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non return valve on a290

R

Rscottdds

Regular Contributor
Half of the non return valve broke on my 290 outdrive. What is the purpose of this rubber valve (I assume to restrict water intrusion to some degree) and can I run it until I can fix it as long as I keep the engine running while its in the water?
-Robert
 
Rscottdds said:
Half of the non return valve broke on my 290 outdrive. What is the purpose of this rubber valve (I assume to restrict water intrusion to some degree) and can I run it until I can fix it as long as I keep the engine running while its in the water?
-Robert
Click to expand...

Robert, I am not familiar with a "non return" valve........ are you asking about the back-flow-prevention flapper at the exhaust outlet area?

SEQ#4 on this schematic?
http://www.marinepartseurope.com/en/volvo-penta-explodedview-7743320-44-17289.aspx



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Rscottdds said:
That part is labeled “non return valve” on that schematic.
Click to expand...

Yeah, the Swedish translation can become rather goofy on some of these items.
Here in the US that is referred to as a back-flow-prevention-flapper, or exhaust flapper.

It is there to prevent a wave surge from flowing back into the exhaust system at low engine speed, whereby it may make it's way into an open exhaust valve.
I would not operate without one in place.


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Thanks. I'll replace it ASAP. I'm not sure when it broke but probably on my last trip out as I always look to see if water is spitting out of it when I flush it at the end of the day. BTW is that normal to have a bit of water spitting out with the exhaust? I assume so because its always been that way since I've owned the boat.
-Robert
 
Rscottdds said:
Thanks. I'll replace it ASAP. I'm not sure when it broke but probably on my last trip out as I always look to see if water is spitting out of it when I flush it at the end of the day. BTW is that normal to have a bit of water spitting out with the exhaust? I assume so because its always been that way since I've owned the boat.
-Robert
Click to expand...

Yes, not only normal, but mandatory that water exits with the exhaust!

You should be routinely replacing the:
..... water neck fitting and special beaded gasket
..... seawater pump impeller
..... drive shaft bellows
..... PDS bearings if no recent history of being replaced

You will also want to be lubricating the PDS bearings during each oil change interval!




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re" "spitting"....Water out the exhaust.... you should be getting about 10 gal/min per 1000 engine rpm out of the exhaust.
 
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