Entropy

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terkio
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Re: Entropy that wasn't as easy as it should be...

Post by terkio » Tue Apr 20, 2021 4:15 pm

JR. wrote:
Mon Apr 19, 2021 5:15 pm
Its as if it is cavitation or vapor locked.
JR
I think you have an air leak.

A tiny air leak at the intake is enough to play havoc in centrifugal pumps.

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JR.
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Re: Entropy

Post by JR. » Tue Apr 20, 2021 4:37 pm

I just noticed a hairline crack in it, so leak sounds like a possibility. While it was failing to prime there were visible bubbles coming from it...

New 1/4 HP pump arrives in a few days.

JR
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terkio
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Re: Entropy

Post by terkio » Wed Apr 21, 2021 1:47 am

:idea: Could the hairline crack be from the lightning strike ?

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JR.
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Re: Entropy

Post by JR. » Wed Apr 21, 2021 9:17 am

terkio wrote:
Wed Apr 21, 2021 1:47 am
:idea: Could the hairline crack be from the lightning strike ?
That is my speculation.... the pump was probably running at the time of the lightning strike less than 100' away, and the aftermarket controller attached to the pump was fried. Too much of a coincidence to ignore.

Saturday I will get some "Y" screw drivers so I can take it apart. My brother suggested that a hairline crack might be repaired with permatex gasket sealer, but I already have a replacement 1/4HP pump on order. I notice that the bottom molding is attached with regular phillips screws so I can remove that. I suspect it is just a spacer to keep the pump from sitting flush on the ground. I'll see if it reveals anything later today.

I notice now that the premium sump pumps use cast iron or steel casings. We'll see how long this next plastic one lasts. These should outlast me...

JR
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Re: Entropy

Post by JR. » Wed Apr 21, 2021 12:01 pm

OK, the bottom casing is all phillips head screws so I was able to get to the impeller. There is no visible crack, leak, or clog. 'There was an o-ring seal between the bottom housing and the pump chamber. The o-ring appears to be in good shape and there was some sediment in the area but no obvious problem. From inspection the the bottom housing o-ring race looked good, the mating race on the pump chamber did not look very smooth, or round.

I put it back together and even tried adjusting the float switch an inch higher but it still paused before priming. I don't feel lucky putting this back under my casa.

I guess I could experiment with putting a bunch of permatex gasket seal on the o-ring to see if that helps make a better seal but even if it did it would not be a good long term solution.

JR
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Re: Entropy

Post by JR. » Wed Apr 21, 2021 3:03 pm

No permatex to be found but I did have an old tube of RTV that wasn't solid. I loaded up a bead of RTV on both o-ring races and then some more in the gap after I reassembled it. For all you kids following along from home this is not an acceptable permanent repair.... This is just some mental masturbation to amuse me while I wait for my new pump.

The good news is I have to let it set up for 24 hours so no touch until tomorrow.

JR
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terkio
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Re: Entropy

Post by terkio » Thu Apr 22, 2021 2:31 am

Well, you'll have a spare 1/2 HP pump.
May be more reliable than brand new, new stuff.
I like old stuff I repair, rather than today's junk.

Can we have a picture of the hairline crack ?

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JR.
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Re: Entropy

Post by JR. » Thu Apr 22, 2021 8:09 am

terkio wrote:
Thu Apr 22, 2021 2:31 am
Well, you'll have a spare 1/2 HP pump.
May be more reliable than brand new, new stuff.
I like old stuff I repair, rather than today's junk.

Can we have a picture of the hairline crack ?
Sorry no hairline crack was found to photograph under closer inspection.

I am still speculating that the problem was lack of an air tight seal between pump chamber and bottom housing. The fact that they used an 0-ring there suggests it was supposed to be well sealed. Upon close inspection the bottom housing looks like an injection molded part so very good dimensional integrity and proper o-ring race. The pump chamber looks like it was probably a cast part. Perhaps machined in a secondary operation to make a good seal when new. Now that pump chamber is no longer perfectly round or with with good mating surfaces or race to seat the o-ring in.

I haven't tested this since liberally applying RTV to the o-ring seal. They say allow 24 hours for RTV to cure. I don't even know if it will work. Even if it does work my new 1/4 hp pump is now due in tomorrow. I will test the crude redneck repair later today and report back.

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mediatechnology
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Re: Entropy

Post by mediatechnology » Thu Apr 22, 2021 9:15 am

Now that pump chamber is no longer perfectly round or with with good mating surfaces or race to seat the o-ring in.
What happened to it?
https://ka-electronics.com

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terkio
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Re: Entropy

Post by terkio » Thu Apr 22, 2021 9:54 am

Inspect closely the O ring for scratch or pinch that could damage its "skin".
As you probably are aware of, O ring seals are mostly excellent, but ask for perfect race surfaces.
I would not expect good result adding some paste or sealant.
I might add some lubricant, as long as it is safe on rubbers ( no pun intended ).

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