Stumped - Replacement Mechanical Seal for Jandy MHP Pump

paradigm79April 26, 2011

My mechanical seal failed recently and I replaced it with identical parts. However when I thread the impeller back on the motor shaft, I run out of threads before the seal becomes preloaded by the seal spring. I've triple check that the seal is the same dimensions as the original. It appears the spring cup needs to be shimmed out a little. The original was not shimmed but it did have a very large bead of RTV around the perimeter and possibly under the lip that may have acted as a shim. Is this common? What shim thickness is required to preload the seal without overloading it? Any other ideas? (I verified its not working by putting it all back together correctly and opening the inlet valve...water poured out the pump backing plate.)

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Sounds like dirt on the shaft's threads or on the impeller's threads or you got the wrong seal set. They should not need shimming. A little RTV on the seal plate side isn't required normally but is still a good idea.


    Bookmark   April 26, 2011 at 10:31PM
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Thanks Scott. I'll double check the threads again but they appeared clean. I've also contacted Jandy and they seem to have conflicting information on which replacement part is correct (although the one I got looks correct). I've ordered another in hopes I got a defect with a short spring height on the first one. Anyone else run into this problem? I've replaced mechanical seals in other pumps and they went together fine, as expected.

    Bookmark   April 27, 2011 at 6:28PM
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