Changed o-ring on filter, leaks under pressure

[kcbaltz]

I have a Pentair CCP320 Cartridge Filter system and recently had to replace the large o-ring that sits between the top and bottom halves because the old one got stretched and wouldn't say in place for clamping.

After replacement, I've been unable to get it to seal under the high speed pressure. I get copious amounts of spray around the metal band clamp. It seems to seal well enough for low speed running, but I'd obviously like it to work for both. Even though it looks similar to what I had before, it seems to me like the new o-ring isn't thick enough because it looks like the top and bottom halves end up almost touching each other. I've tightened the metal clamp more than I previously had to, to the point I'm afraid to go more. The old o-ring had actually developed a flat side. I'm assuming it was originally as round as the one I just bought.

This is the o-ring I bought: Pentair 39010200 Tank Clamp O-Ring Replacement Pool and Spa Filter

I did lube the o-ring with magic lube, but that hasn't helped.

I checked for cracks in the lid and didn't spot any. As I'm typing this, I'm not sure if I checked the bottom for cracks, so I'll have to do that. Any other thoughts if that's not it?

 

[MSL]

Some filter o-rings do have a flat side. Is the new o-ring listed as a replacement for your specific filter model?

 

[kcbaltz]

As far as I can tell, 39010200 is the right part number and that's what I ordered from Amazon.

 

[ewkearns]

From what I see, you might need either a gasket or an o-ring, depending on the age of your unit. Either a #9 or a #10....

http://www.pentairpool.com/pdfs/178558MOM.pdf

 

[kcbaltz]

I'll check the tag on the thing when I get home, but it was installed in the early 2000's and that doc says the gasket was needed prior to 11/98, so unless they gave me a really old piece of stock, I don't think a gasket is needed.

 

[kcbaltz]

Looking at the label, I think the filter is a 2002 model, so no gasket needed.

Any other thoughts what might cause it to leak with a brand new o-ring?

 

[gary300]

You need to tap the clamp several times around with a rubber mallet as you tighten the bolt. This help it to seat. Use moderate pressure on the mallet.

 

[kcbaltz]

I have tried that. I can try it again. I"m afraid I've probably overtightened the band clamp because I think you're supposed to stop when the spring closes entirely, which I think I've had to go past just to get it to tighten at low speed pressure.

 

[ewkearns]

The part is described as: "39010200, O-ring, tank clamp (.470 O.D.)." Can you verify that it is .470 diameter?

 

[kcbaltz]

Funny you should ask. Last weekend I pulled out the o-ring I got and it was .470in in diameter. The old o-ring is no longer round, but it varies from .49in to .55. I see that at some point they switched from a 7/16" o-ring to a 1/2", so I ordered a 1/2" to try that.

 

[kcbaltz]

Success! The 1/2" o-ring works great. The part I ordered (O-333-9) is not OEM, which was expensive, but seems to work.