Check the impeller regularly and have a spare.Impellers are the heart of an engines cooling system and require regular inspection and replacement under normal operating conditions. Running through silty or sandy water or running a pump dry can ruin an impeller quickly and cause the engine to overheat. It is important to monitor cooling water outflow and replace the impeller at the first signs of reduced outflow. Sierra replacement impellers are engineered to meet or exceed Yanmar specifications to give boaters and technicians the confidence of an OEM fit and function. These impellers are compatible with Yanmar 1G diesels manufactured between 1980--2009. Because unexpected failures can happen, it is important to have a spare onboard to save the day. Use our Engine Parts Selector or call 1-800-BOATING with your engines serial number to confirm this is the correct impeller for your engine. Key Features Impeller is engineered to meet or exceed manufacturer specifications OEM fit restores function and makes installation predictable Replaces Yanmar p/n 128176-42071 The Sierra Engine Parts Selector In addition to impeller kits, we offer a wide variety of other engine parts manufactured by Sierra. To see if we have the part you need, see ourEngine Parts Selector, where you can search by engine make, serial number and model or year of manufacture.