Re & Re Waterpump Impellers on a 250 SX TXRY

[vangrady]

I recently re & re'd my water pump impellers last fall and ran the machines twice without any problems. I then experienced overheat problems after the first start up of the 2009 season. Some of the local mechanics at my marina have suggested that maybe the impellers were inserted into the housing with the fins facing backwards to the rotation of the pump shaft. They say that either some or all of the fins could be stuck with the fin set in backwards or that the impeller might have become detached from the hub on start up if it was put in with the fins backwards. Based on your experiences can this happen??
Thank you.

 

[gw204]

If they ran fine twice I doubt it's the impellers. Have you checked/replaced the thermostats and poppit valves? I would check those and then drop the lower units to check the impeller orientation.

I got into the habit of drawing an arrow on the pump housing before I take the impeller off so I don't have to remember which direction the driveshaft rotates.

 

[Lainie J]

Yamaha

I am having the same problem with one of my four stroke 225's. Just had the pumps, thermostats and pop its changed. At idle after 5 or 6 minutes the engine gets hot, run it at higher rpms and it cools right down. My mechanic is suppose to drop lower unit in the next day or two and see if he sees any problems. He did say that he just a similar problem with same motor on another customers boat and he fixed with a shim under the pump housing or somewhere. He said that worked but i never heard of this before.

 

[vangrady]

I would be interested to find out more about the shim solution. Thanks for the feedback guys!

 

[Grog]

There's 2 ways to do the water pump, just buy the impeller or buy the kit. The kit comes with a new plastic cover, steel shim, steel cover, and o-rings. Over time the steel shim wears and you have grooves worn in them.