Picture of running a dry impeller

[johnyrude200]

Earlier in the year on the green boards there was a thread about someone with a JW (3hp) who was having overheating problems. Part of that thread involved a post with a picture of what happens to impellers when you run them dry. Can someone re-post that picture on this thread? The green boards, apparently, delete posts that are more than 5-6 months old automatically.

Thanks!

[Mumbles]

Here’s some failed impellers I’ve come across. I think the first one is melted a bit while the others died of old age or had the flywheel turned backwards. Somewhere I have what’s left of a Yam 9.9 impeller. The owner was warming up his kicker and main mover at the dock and when it was time to go, he tilted it and took off forgetting it was still idling away.

[johnyrude200]

there was an old black and white diagram of what happens to impellers based on the amount of time they are run dry, for instance, 5, 15, 30, 60, 90 seconds. It showed the progression of degradation. Frank I remember you being in on that thread. The guy had a driveshaft that had worn a hole in the water tube in the exhaust housing, even though there was water coming out of the exhaust relief holes.

[dave-bernard]

running in a plastic housing they deteriorate much faster.

[mr-asa]

quote Dave Bernard:

running in a plastic housing they deteriorate much faster.

Interesting, Because the plastic has a lower melt point, so it breaks down quicker?

[dave-bernard]

not as much heat transfer from the impeller I guess.

[dan-in-tn]

It is the friction of the impeller turning inside a dry housing. Just a small amount of water (fuel, oil, something) lubricates and gives a little more time. OMC always told us 7 seconds was all it took to start damage to the housing. Now I am talking about plastic housings. Once they warp it’s the beginning of the end. The impeller can be compromised also. If you think about the damage is comulative then it doesn’t take much to do harm to your pump. No excuse to start out of the water. At least wet the pump before popping the motor off!
Cast aluminum housing are more forgiving, but damage to the impeller is the same.

Dan in TN

[r-delawter]

Once more, Some great information for us newer members. A fair warning as to what can happen.

[Mumbles]

Take it from this guy. He knows!

[wiscoboater]

quote Mumbles:

Take it from this guy. He knows!

Now that’s damm funny right there.. I don’t care who you are

[Author]

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