ran pump dry

yeah, i know. i didnt do it on purpose, but while redoing my loop last night an air pocket got into the pump. and how you may ask, i was tipping the case to get the big air pockets out. love irony. at any rate, the pump ran dry for approx 5-10 sec before i was able to shut it off. now i know your not supposed to run the pump dry, but how bad did i hurt my pump? btw, its an MCP655

Should be fine.

=ACID RAIN= said:

Should be fine.

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yup.. itl be fine. iv done it for 3-4 sec b4 and my pumps have been fine. just try not to do it for anything longer than that.

thanks for the response guys. makes me feel alot better about my mistake.

You will not hurt these pumps running them dry for only a few seconds like you did. The impeller is plastic with magnets molded into it. It sits on a ceramic ball and spins on that, held there by magnetics. Its the water that keeps the plastic and ceramic cool and lubricated so the ceramic ball doesnt heat up and just melt into the impeller plastic. This is why you do not run these pumps dry for any lenght of time. Those few seconds of yours didn't hurt anything. You can always check it if that would make you feel better, just pull the impeller straight off cause its only held in place by a magnetic field and look at the contact point in the center. I am sure you will find it in perfect smooth shape.

The only other thing to be concerned with when a pump runs dry (other than what GTFouts covered) is the seal keeping the water from leaking out where the motor shaft enters the pump housing. Typically on small pumps like these, they're a spring loaded ceramic disc that is also cooled by the flow of the water. When it runs dry, it heats up and potentially cracks. When you've discovered that the pump is running the dry, the best thing to do at that point is to shut it off for a few minutes to let everything cool down slowly. If you quickly restore the water to it before cooling that seal down, that is where you run the greatest risk of seal failure.

Tweaked! said:

the seal keeping the water from leaking out where the motor shaft enters the pump housing.

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What? You're not using a mag drive pump like the rest of us?
The whole purpose of a magnet drive pump is to avoid having to have any shaft seal at all. I'm not aware of any WCing pumps that aren't of the mag drive type.

billb said:

What? You're not using a mag drive pump like the rest of us?
The whole purpose of a magnet drive pump is to avoid having to have any shaft seal at all. I'm not aware of any WCing pumps that aren't of the mag drive type.

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maybe cheapie pumps?

Most of those are still mag drive. It's simpler to make a mag drive pump than it is to make a mechanically linked pump these days. Only really powerful pumps are direct drive these days (like high output Bilge pumps). At high torque levels it becomes difficult for a mag drive pump to keep the impeller from stalling and the shaft from free spinning. A car's water pump would be an example of this.