Has anyone fixed a leaky backwash drain on the Pentair 4000 filter by replacing the seal on the rotor valve?

This part is part of the seal and it is in poor condition, so it will probably leak.

So, after replacing the part, it still leaks and you say "Well, what are you going to do about the leak, it's your problem, you're the repair person. I'm not paying until it is fixed properly".

The service person says "The bottom part is damaged and it won't seal 100%".

You say "Well, you should have told me that a repair wasn't going to work, you're the expert, I'm not paying".

The smart repair person does not let the customer bully them into a stupid repair.

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please explain what could go wrong.
The inlet or outlet connection starts leaking so you replace the bottom half for $480. Messing with it breaks the $413 band clamp. 2 months later the top tank cracks from 18 years of UV exposure. ($657). Plus labor and an unmeasurable frustration.

You have a several professionals telling you it's time to move on. 18 years is a good run IMO.
 
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You are confusing the body that the rotor valve fits into with some other filter's. The rotor valve fits inside the Pentair 4000's solid tank body, as pictured.
Interesting. Because no one in my area would actually sell one of those filters, I've only seen the ones with the brass backwash valve. You should clearly be able to see, from that picture, that the body is worn out. Out of tolerance = diameter is now too large for the seal to actually seal. All of that sandy debris, over time, just scours the opening larger.
Here's an example the only sure repair (but you will also have to factor in the cost to replumb):
 
Interesting. Because no one in my area would actually sell one of those filters, I've only seen the ones with the brass backwash valve. You should clearly be able to see, from that picture, that the body is worn out. Out of tolerance = diameter is now too large for the seal to actually seal. All of that sandy debris, over time, just scours the opening larger.
Here's an example the only sure repair (but you will also have to factor in the cost to replumb):
Here are additional pictures from different angles. Can you spot any abnormalities? One quarter of a circle close to the edge seems to have a slight groove or indentation, where the seal would have met the wall, that is absent from the rest of the edge close to the top.
 

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Why didn't you say that in the first place?

This thread has mostly been a huge waste of time.

Make use of what?
So, it was worth your time until I revealed that that I was thinking of letting someone else have it. Now that I may have a profit motive your efforts have become a huge waste of time. I do not know what your motive is for visiting this site, but the rest of us are here to exchange information, regardless of how it may be used.
 
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You could have just told us that you had already replaced the part.

I'm not sure how you plan to profit, so that makes no sense.

Even if you could profit, it doesn't make any difference to me.

In any case, hopefully the filter will work well for you without any problems.
 
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The main problem for a service person is that you want them to take all of the risk.

If the fix works, you win because you don't have to buy a new filter.

If the fix does not work, you will refuse to pay because the filter is not fixed.

What is the service person supposed to do, spend another hour taking the filter apart to get the part back and return the part?

The part is now used and it cannot be returned.

So, now the service person is out 4 hours plus $150.00 in parts and other costs like gas to get to your property.

The main question was why the service people did not want to replace the part.

If you want to take the risk of buying the part and spending the time to replace it, then that is your choice and you might win or lose.

For a service person, you have to know when a job is not worth doing.
 

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You could have just told us that you had already replaced the part.

I'm not sure how you plan to profit, so that makes no sense.

Even if you could profit, it doesn't make any difference to me.

In any case, hopefully the filter will work well for you without any problems.
I want to get the opinion of someone who is knowledgeable instead of relying on hope about whether the filter is still viable. Can you tell me whether there is anything abnormal about the rotor valve compartment in the pictures below. For a quarter of a circle, close to the outer edge, there appears to be a slight indentation or groove that matches the position of where the valve seal would have been, while the rest of the wall near the outer edege of the cylindrical compartment is smooth, without a groove. Can a new seal be installed on the rotor valve to make a leak proof seal?
 

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Can you tell me based on your knowledge whether there is anything abnormal about the rotor valve compartment in the pictures below.
I have already told you that it is in poor condition.
This part is part of the seal and it is in poor condition, so it will probably leak.
You can maybe try to polish it out if you want to make it smooth, but the hole is going to be too big and it probably won't seal.

Maybe you can have a new rotor made that is larger and have the hole polished out.

Maybe contact an engineering firm to get them to do the necessary plans and then find a Machine Shop who can do the work.
 
So, it was worth your time until I revealed that that I was thinking of letting someone else have it,
No. If you already replaced the part, it still leaks so now want a service person to try, which they don't want to, it changes the whole equation.

If that's the case, you should have lead off with that information.

If you replaced it some time ago and want a service person to try to hopefully get even longer this time, you should have lead off with that instead.
 
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Has anyone fixed a leaky backwash drain on the Pentair 4000 filter by replacing the seal on the rotor valve?

Is there a trick to fixing it? It seems like a simple solution, so why would it fail?
The seal does not come as a separate part if that is what you are asking.

The rotor comes as a single part with the rubber seal built in.

The bottom hole in the filter gets scratched over time from sand and grit falling down and grinding against the plastic as the rotor is turned.

At 18 years old, the plastic is deteriorated and scratched.

For a service person, there is probably less than a 50% chance that the fix will work and probably more than a 50% chance that it will leak.

If it leaks, maybe they can spend another several hours trying to clean up the plastic to make it work, but you will not pay for that since you were quoted $450.00 to do the job.

So, the best case scenario is that the service person has about a 50% chance of getting paid for the job, which makes the pay statistically worth $225.00.

If the job costs are $175.00, the person is making about $50.00 for about 5 hours work, which is $10.00 per hour.

As the pool owner, you might have an incentive to try the repair and you might want to take the risk.

A service person has zero incentive to take the risk because it is not their pool and not their problem.

Being in Los Angeles, you can probably find plenty of new service people with little experience that you can badger into taking the job and shifting the risk onto them, but it is an unscrupulous way to act.
 
The only way that it might be worth it was if you paid me the $450.00 up front with a written agreement that you accept all risk of the repair not fixing the problem.

In other words, if it still leaks, I do nothing for you other than maybe say “Well, that’s too bad” and maybe make a slightly sad face.

Even then, I would not do it because I do not believe that it is in your best interest.

A service person should only do work where they believe that it is in the customer’s best interest.
 
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The only way that it might be worth it was if you paid me the $450.00 up front with a written agreement that you accept all risk of the repair not fixing the problem.

In other words, if it still leaks, I do nothing for you other than maybe say “Well, that’s too bad” and maybe make a slightly sad face.

Even then, I would not do it because I do not believe that it is in your best interest.

A service person should only do work where they believe that it is in the customer’s best interest.
So you say that based on the evidence I provided it is unlikely to get fixed. But if you were going to give it a try, you would smooth out the side of the indentation/groove, slip a new valve seal on the rotor valve and slather a gob of lube to make it fit. Would a brand new valve seal tolerate the slight deviation and provide a leak proof seal, or is the compromise you would've made to the design of the compartment likely to cause it to leak?
 

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