Exhaust Riser Valve

[alanwp]

My Volvo Penta 4.3 GL PEFS has a valve (Part No. 3857761) on each exhaust riser connecting to the carb spark arrester. I have >500 hrs. on the engine I'm wondering if and when they should be replaced as a preventative maintenance item. Since the engine runs well and I don't fully understand the function of the valves, is it best I leave them alone? I'd appreciate any information. Thanks, Alan

 

[jerryjerry05]

Re: Exhaust Riser Valve

They are the same as a PVC valve on your car.
Change them.They are only $15

 

[alanwp]

Re: Exhaust Riser Valve

Thanks for your input. Further reading suggests they are siphon break valves to keep water out of the intake mainfold at low rpm. If this is it's only function why not just use a plug? Volvo Penta part 3857761 is $39.00 ea. online.

 

[bonzoscott]

Re: Exhaust Riser Valve

Designed to remove excess gasses form the carb ventri. If you plug 'em, things will get dirty and create further maintenance. I would think you could clean the valves, but that is risky compared to new.

 

[jerryjerry05]

Re: Exhaust Riser Valve

"Further reading suggests they are siphon break valves to keep water out of the intake "
Please explain??
They shouldn't have anything to do with water. They allow excess air/blowby from the crank case to be sucked into the carb/throttle body.
3856884 $14 Volvo Penta Marine Engine Parts and Accessories Online Store - Volvo Penta
Pics?

 

[alanwp]

Re: Exhaust Riser Valve

The valve I'm refering to (part 3857761) screws into the exhaust riser casting that also carries coolant water. You are refering to the PVC valve connected to the valve cover.

 

[jerryjerry05]

Re: Exhaust Riser Valve

I see the part your talking about.
That's hooked to the intake on the flame arrestor?
How about a pic.