Shaft Seal Leak on One-Year-Old IntelliFlo VSF

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JamesW said:
The glue is sloppy and the white part of the ceramic is too gray.

The gray indicates that the primary ring material has worn off and embedded into the ceramic, which is not going to happen with a good seal unless the seal ran dry for a long time.


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Very odd indeed. I don’t know what to think. I’m almost certain the seal is genuine Pentair and after assembling the pump, I filled the pot completely with water and then ran the pump. Within 20 seconds it was primed and running and it only ran for half a day before I disassembled it again. I’m not sure how it could have ran dry in that short time. I guess I will see once I get another seal and a new impeller and redo everything. Though I am doubting buying the Pentair Seal Kit (P/N: 356198) again if the seals that come with them are bad.
 
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Thank you for all that amazing info James!

I got another seal kit and a new impeller. The new impeller has a dramatically better looking seal seat and I cannot press in the ceramic seal by hand, the way I am able to with the old deformed impeller. It’s looking more and more like it was the impeller.
Left - Old / Right - New
Old one is on the left. New one is on the right.

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The old impeller

IMG_2346.jpeg
The new impeller


And I got the same Pentair seal kit since that’s all they had.
IMG_2344.jpeg

The new seals
IMG_2347.jpegIMG_2348.jpeg
 
I would use Seal Lube to install the ceramic with the rubber boot.

I would use aquarium sealant on the metal cup to make a watertight seal in the seal plate.

Allow the silicone to dry completely and do not get any on the faces of the seals.

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JamesW said:
I would use Seal Lube to install the ceramic with the rubber boot.

I would use aquarium sealant on the metal cup to make a watertight seal in the seal plate.

Allow the silicone to dry completely and do not get any on the faces of the seals.

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Thanks! I used 100% waterproof aquarium safe silicone adhesive but I could not source US seal lube anytime soon so I followed pentair’s suggestion of mild soapy water and I pressed it in using a 3/4” PVC coupler, both of mwhich worked like a charm.

I completed the swap in the morning and it’s been drying since, so when I hook the pump back into the system later this morning, it will have reached or passed the 24 hour mark.
 
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Is that pump pot filling up all the way after the pump primes? It looks like there is a lot of air in the pot.
 

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JamesW said:
I would use Seal Lube to install the ceramic with the rubber boot.

I would use aquarium sealant on the metal cup to make a watertight seal in the seal plate.

Allow the silicone to dry completely and do not get any on the faces of the seals.

View attachment 548208

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Seals have to be installed with any silcone sealant still uncured (wet), just like the factory does, or the cured (dry) will interfere with proper fit. A thin layer on the rubber, right at the "bend" in it, and a thin layer on the stainless cup and install. Works as an install lube and then improves the mechanical seal with the impeller and sealplate.
 
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JoyfulNoise said:
Is that pump pot filling up all the way after the pump primes? It looks like there is a lot of air in the pot.
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Yes; once priming is complete, the filter fills up, and all the bubbles leave the system, the pot fills completely and stays full permanently, at all speeds, and even when the pump is off.
 
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DavidArmenB said:
About four hours in, still running at 2000RPM, and not a single drop. I think my shaft leak has been mended!
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Glad to hear it's working as expected. This is a great thread with lots of good photo's covering the various aspects of pump motor shaft seal troubleshooting. Goes to show that even the most subtle of defects can cause problems. Thank you for posting all the images and info (y)
 
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In my opinion, the metal cup in the plastic hole is not a really good seal design.

It relies on the interference fit between the metal and plastic and this requires the parts to be very smooth and tight.
 
JamesW said:
In my opinion, the metal cup in the plastic hole is not a really good seal design.

It relies on the interference fit between the metal and plastic and this requires the parts to be very smooth and tight.
Click to expand...

Seems like it’s designed for a residential/field service situation. In a real motor application, a seal like that would be press-fit into place using an arbor press with a special fixture. Removal would be done using something similar to a bearing puller that you find in an auto shop. None of those tools are capable of being used easily in the field. So I think Pentair was going more for quick serviceability than a quality design.
 
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JamesW said:
In my opinion, the metal cup in the plastic hole is not a really good seal design.

It relies on the interference fit between the metal and plastic and this requires the parts to be very smooth and tight.
Click to expand...
Whisperflo has been in production for 30+ years, virtually unchanged, since Purex first introduced it.
Polaris PB4-60 booster for at least that long. Both (along with other brands) use that design with no issues.
They are very precision-molded plastic that can last decades.
The first Whisperflo I installed was in 1994 or 1995. It is still running with only 2 seal replacements in that time. Both leaking seals were caught before they could damage the motor, which is still original. Seals do wear out. Motor manufacturers, especially Century, used to recommend a seal be replaced at 5-year intervals. Don't know anyone that does that.
 
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