www.iFourWinns.com

Hello,

I know how to change the impeller, but the question I have is, if there is a recommendation of OMC/Volvo how often you've to change it. Each year, every two, five, six years.
I can't find any recommendation in the workshop manual.

Many people with Volvo Penta change the impeller every year... or at least every other year. Broken impeller vanes can clog up passageways in the thermostat housing or the engine block. Much better to replace before it becomes a problem.

Having said that, The Cobra impeller is more sturdy and less likely to shed impeller vanes than the VP. It is rubber age and stiffness that usually defines the end of a Cobra impeller. 3-4 years is possible, but personally, I would change every 2 years. Especially since it is so easy on a Cobra drive.

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"Knot Easy" 2000 Horizon 240 Volvo 5.7GS /SX
tow: 2017 Honda PILOT EXL-AWD
prev. boats:
'87 Chaparral 198CXL 4.3 OMC Cobra
'69 Jetstar 16ft Ski Boat, 115hp Yamaha
'68 Aluminum Jon Boat, 3hp Sears
'64 Water Wings

I go by the output of water I see coming from the transom mount when I run the engine on the water hose and general running temps. If the water output looks like what I get with a new impeller and running temp on the hose is about 160* then it is fine for the up coming season. To be on the safe side you can change it every 2 seasons. If you boat in shallow water and Sandy bottoms they do not last as long because of wear both on the blade tips and the wear plate. If you boat in deep waters with muddy bottoms then they will last much longer.

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88 Four Winns 200 Horizon
4.3 OMC Cobra-4bbl
2002 Walker Bay 10/2012 Suzuki 2.5
2008 Walker Bay 8

1998 Jeep Grand Cherokee 4.0/Selectrac
2007 Jeep Grand Cherokee 5.7 Hemi/Quadradrive II