Raw water cooling

[Jtoben]

Our Volvo MD17C has run hot since we bought the boat in 2001. (11.0a). When we changed the impeller this past spring, we found a dog ear missing, and removed two side hoses leading to the thermostat to track it down. Not only did we find the impeller ear, but also two small plugs of zebra mussels, which probably have been impeding our full water flow through the engine for years, since we can now run the engine at the higher rpms appropriate to the engine without overheating the engine at all! We have the sail drive, and would NEVER have believed those mussels could have gotten past the internal screens in the drive unit...never mind through the impeller and those small diameter hoses and t-turns.... What a treat to not worry about the engine temp on longer trips where we have to motorsail. Just wanted to pass this along, as we had tried tracking the source of this minor overheating for years.

 

[Jtoben]

PS. Didn't want to imply this was the first time I'd ever changed the impeller!

 

[Mark Maulden]

You can also pull raw water from a bottom thru hull and go through a strainer. Don't have to worry about the passages in s/d plugging up and the s/d doesn't need the water.

 

[Jtoben]

Right, we've never had an issue with the sail drive plugging up, or low water flow through there...that's why we were shocked that the zebra mussels had somehow made it through all those internal screens between the lake and where we found them! We figure they must have been there since the PO had the boat. We should have checked hoses all the way to the thermostat right off the bat, KISS.