Vanes in wrong direction

[Deadline]

I replaced my Johnson impeller before winterizing the engine, but the engine overheated before I could get the antifreeze in.

Turns out the impeller flanges were directed the wrong way, per the instructions! When I reversed the flanges, the engine ran fine and took the antifreeze. What's with that?

 

[Jeff]

As a side note to anyone having an overheating problem check the gasket in the lid of your strainer basket. My lid has a wing nut which was hand tight but not providing enough squeeze on the old cork gasket. I made a new gasket and my overheating woes were cured. Of course I replaced the impellar first and discovered the problem persisted at higher RPM's. That's when I figured it best to start at the thru hull and work my way down the line.

 

[Franklin]

Interesting. It wasn't leaking but would draw air at higher RPMs? Is the strainer above the waterline?

 

[Jeff]

I'm certain it's below the water line. The middle of the bowl is at the height of the prop shaft packing gland. I have been chasing a leak on the galley floor but didn't suspect anything with the engine because I would find the puddle when arriving at the boat at the beginning of the weekend. It just could be I've had two leaks on the galley floor. Can't figure out whether it's the frig compressor condensation or a fresh water problem. With the frig now off and the water tank empty it should be easier to figure out in the spring.

 

[Benny]

The diagram shown is not a Yanmar diagram and needs to be interpreted according to the application. As you can see the arrows point to the discharge port and one is marked by straight lines and the other by crisscrosed lines. Depending on which is the discharge port the corresponding pattern on the rotation arrows shows the proper direction of rotation for the impeller. The small diagram on the right is incorrect; it has the direction of rotation wrong. I'm looking at the Yanmar shop manual and it shows that for the 2GM or 3GM the rotation is counterclockwise and the vanes are bent back clockwise. The information on your diagram is conflicting at best. Just paint a small arrow on the body of the pump showing which way the vanes should go for future reference or should you need to do under adverse conditions like pointed out.

 

[george schmidbauer]

the small diagram is correct. the water comes in from the right and moves around the bottom and exits to the left as the vanes are closed by the cam.

 

[Warren Milberg]

I'm not sure what engine/water pump you have, but on most Yanmars with a cam in the water pump housing, it makes no difference which way you insert the impeller: they will sort themselves out and turn in the proper direction as soon as you start the engine. You can test this yourself quite easily. Just take off the water pump, insert an impeller (or use the one in there) and turn the shaft by hand to see how the vanes of the impeller will rotate in any direction you spin the shaft.

 

[Tom H31]

I agree with Warren, it doesn't matter how you install the impeller. Once the engine is running and the pump rotates in the right direction, the impeller blades orient themselves properly.:neutral: