Pentair 160301 Drain Plug Leaking

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Merchant

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Jun 14, 2020
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Hello! I am new to the forum but have read enough to know there are really nice and knowledgeable folks here. I apologize if this is a topic posted up all too often.

I have a Pentair 160301 cartridge filter. The pool was installed a couple years ago (first pool) and we were idiots when it came to landscaping. Most of what we planted craps in the pool constantly. So...I am adept at cleaning the filters.

The last time I cleaned the filters, I noticed the drain plug had some grit in the threads and that half of the threads had been ground off. So I ordered another plug off Amazon.

This morning, I noticed a slight drip by the drain plug. I got the 7/8 wrench and tightened a bit and the top of the plug broke off from the threads. Great! Immediately turned everything off and started disassembling.

I removed the bottom of the filter shell so I could turn it over and get to the threaded portion still stuck in the shell. Luckily, I was able to remove the threads. Leslie's had a replacement (thank goodness).

Before putting the new plug in, I took a pick and cleaned out the threads in the shell as best I could. They looked a little worse for the wear. I put a few wraps of Teflon tape around the plug and some petroleum jelly on the O ring. I screwed it back in and got it reasonably tight.

After putting everything back together, the plug still drips. Argh! I grabbed my channel locks and gave it another eighth of a turn. It helped, but still dripping. I'm scared to tighten the plug too much for fear of stripping out the shell. That would be a $500+ mistake. And that's IF you can get one.

Before draining and taking this all apart again, I thought I'd ask for some expert advise. Any thoughts?
 

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The advice I learned from this forum years ago was to never remove the bottom drain plug on a Pentair filter.
When I clean my DE filter I use a wet/dry shop vac to remove the last of the water and old DE.
In your leak repair situation I would have done what you described except not used petroleum jelly on the O-ring. Best to use silicone grease specifically for O-rings.
 
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Thanks Oly. I used petro jelly as that is what I've always used on the O rings in my home brew kegging system. Never had a leak. But I understand this drain plug is likely under much greater pressure. And I don't have to worry about being food grade.

When you say you never remove the bottom drain plug, how to you clean out the bottom half of the shell? I guess I'll need to remove it from the system and spray it out upside down? Today was the first time I had ever removed the bottom half of the shell. It was pretty easy, so I like your solution. IF I can get this thing to stop dripping, that drain plug is never coming off again.
 
I dunno about never removing a drain plug, I remove mine at least once per year. Never had a problem with it.

1. Stop using petroleum jelly on o-rings, that's incorrect. Silicone lubricant is the correct choice. Petroleum jelly can weaken the rubber that the o-ring is made from and cause cracking/disintergration.

2. That does not look at all like the correct plug. The standard Pentair plug is a knurled black plastic plug with a 7/8" hex nut shape on the bottom. What you have there looks like a standard PVC drain plug for a wall clear out. I do not believe the the threads are the same or, if they are, the Pentair bottom is probably a straight walled tap whereas standard pipe thread is canonically tapered. You won't get a good seal if that's the case.

I suggest you order the correct plug from a pool shop that sells Pentair OEM parts or try Amazon.
 
Oly said:
The advice I learned from this forum years ago was to never remove the bottom drain plug on a Pentair filter.
When I clean my DE filter I use a wet/dry shop vac to remove the last of the water and old DE.
Click to expand...
Me too. I learned this from a pool service professional who cleaned my cartridge filter before I learned how to do it. (I watched him and didn't need him again.) He said he had seen damage both to the plug and the shell if tightened too much.
Merchant said:
When you say you never remove the bottom drain plug, how to you clean out the bottom half of the shell?
Click to expand...
Shop vac as @Oly said.
JoyfulNoise said:
I dunno about never removing a drain plug, I remove mine at least once per year. Never had a problem with it.
Click to expand...
Buy me a lotto ticket, please, daddy, please?
 
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Rocket J Squirrel said:
Buy me a lotto ticket, please, daddy, please?
Click to expand...

Been doing it for 10 years and have never had a problem. If you know how to turn a wrench, it shouldn’t be an issue. In fact, the use of textured plug tells you that it doesn’t need to be more than hand tight anyway….

… But I recognize that some may feel inadequate to the task and probably didn’t learn any mechanical skills beyond what they picked up from their Litt’le Tikes tool set and Tonka trucks. So yeah, definitely don’t touch the drain plug …
 
There are several ways to achieve the same goal.
As Sly and the Family Stone sings "Different strokes for different folks"
I won't risk removing a brittle plastic plug when my shop vac makes quick work of the job.
Who wants or needs a hole in the bottom on a pressurized vessel anyway, access is easy.
I don't like cutting holes in my roof either if I can help it.
 

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Never had a problem with mine, though I detest Pentair's design of the stupid thing. It is in a horrible place, right below the plumbing inlet/outlet. They should have kept the original pac-fab design that had it coming out the back, side-mount, and with standard NPT threads that you could plumb with regular 1.5" PVC to a drain, or put a ball valve on it, etc.

I agree that looks like a standard NPT plug. You may have to use some teflon tape to get it to seal, because while the Pentair threads seem to match 1.5" NPT, they don't seem to be tapered like NPT threads--so it's an imperfect fit.
 
This is how my drain was modified by the builder.

1657653133023.png

The part number on the end fitting shows Spears 435-015. It's standard FIPT or NPT thread. HD sells it own version of the fitting.

I can't get a good look at the elbow coming off the filter, but I believe it's a 1-1/2 in. PVC Schedule. 40 90-degree MPT x S Street Elbow Fitting.

Should be pretty easy to modify. If you can get the elbow water tight in the filter, you won't have to risk removing it in the future.
 
The reason why the plug is not NPT is because the threads are NOT the sealing surface. There is a yellow o-ring that fits past the threads onto the lip of the cap and that is what provides the seal. So hand tight is all you need. It gets over tightened because people (and the so-called “professionals”) lose the o-ring and then try to seal the hole with the plug and pipe thread sealant. They over tighten it because you can’t create a good seal that way with straight threads and then they continue to tighten because they don’t stop to think through the problem. Then the threads get damaged or the plug gets warped.

It’s not a failure of design … it’s a failure of understanding.

As for embrittlement … 10 years in direct AZ sun, heat and dryness … no issue.
 
I suspect that modification was done with a 1 1/2" MPT to slip adapter, and then a slip elbow (edit: looking closer, nope--not sure how they got that elbow in there). There is not enough clearance to screw in a threaded elbow. I've considered doing something like that to mine.

My issue with the design is where they placed the drain plug & orientation. If you have any kind of crowded pad, it takes a contortionist to get to.
 
jedigrover said:
I suspect that modification was done with a 1 1/2" MPT to slip adapter, and then a slip elbow (edit: looking closer, nope--not sure how they got that elbow in there). There is not enough clearance to screw in a threaded elbow. I've considered doing something like that to mine.

My issue with the design is where they placed the drain plug & orientation. If you have any kind of crowded pad, it takes a contortionist to get to.
Click to expand...

Yes, I think you're right. It doesn't look like there's enough room to thread on an elbow. I tried to get the part number on the elbow, but it's not readable.

1657750678752.png
 
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