Cat 3535 no pressure

[JGinther]

Spring pressure doesn't matter. Only the check seal matters.

 

[OurTown]

I talked to Cat pumps today and they suggest to get a seal kit because of the pump age. (of course they want to sell parts) He said it was unlikely that it was the check valve or regulator even though I suggested that it might be. He also suggested disassembling it and to check the head for washout first before buying parts. Seems logical.

 

[OurTown]

Also he suggested to replace the valves (again more parts sales) but to me they did not look that bad. Those are pretty easy to change out later if the seal kit does not fix it. $335 for the seal kit and $544 for the two valve kits.

 

[JGinther]

Well that's unrelated... If the pump is below your water tank, the described issue will not happen without something like your air compressor forcing it to happen. The reason your pump doesn't have pressure at startup is because there is air in the pump. Its pretty much impossible to get atmospheric air to into a pump which always has head pressure water trying to push its way out. I bet your problem goes away when its warm out (assuming the blowdown is tied to temperature).

 

[OurTown]

I should be able to check for washout by only removing the head but leaving the manifold on. Is that correct?

 

[OurTown]

Well that's unrelated... If the pump is below your water tank, the described issue will not happen without something like your air compressor forcing it to happen. The reason your pump doesn't have pressure at startup is because there is air in the pump. Its pretty much impossible to get atmospheric air to into a pump which always has head pressure water trying to push its way out. I bet your problem goes away when its warm out (assuming the blowdown is tied to temperature).

It does not seem to go away when it warms up but I will pay closer attention to it. It does not sound sound like cavitation when the issue happens.

 

[JGinther]

I should be able to check for washout by only removing the head but leaving the manifold on. Is that correct?

I wouldn't waste my time with that if i were you. You said your pressure is good the rest of the time. It wouldn't be with a washed out head. Depending on the location of the washout, you would have pulsation all the time, or valve chatter from cavitation along with (usually) a water puddle under the pump.

It won't sound like cavitation since the pump isn't primed. Cavitation only happens when the pump is primed.

 

[OurTown]

I wouldn't waste my time with that if i were you. You said your pressure is good the rest of the time. It wouldn't be with a washed out head. Depending on the location of the washout, you would have pulsation all the time, or valve chatter from cavitation along with (usually) a water puddle under the pump.

It won't sound like cavitation since the pump isn't primed. Cavitation only happens when the pump is primed.

Okay. I had to think about it for a minute. If I push the reset button on the plc keypad one of the things it does is blow down. (no matter the temp outside) If I pull the hose off the pump head with the check valve attached (if I can) then press the reset button to blow down. If it pushes water or air back out then the check valve is probably bad.

 

[I.B. Washincars]

I agree with JGinther. If your head was washed out the pump would be pulsating. Pretty much the same with valves, no pulsation, no problem with them. I've been at this for 50 years and could probably count the valves I've had to replace on one hand and still have enough fingers left to pick my hose.

 

[OurTown]

If it is the blow down air getting back to the pump then I should be able to replicate the problem by getting it to blow down multiple times. Also it should then push air bubbles back into the gravity feed tank. True?

 

[JGinther]

Yes. But it doesn't take much air to get the pump de-primed. It takes quite a bit more to displace enough to get all the way to the tank.

 

[MEP001]

I've almost never had to replace valves in a Cat pump. IMO they aren't a wear item. I do keep a set on hand as I've had a spring break and early in the life of the 5CP models I had some poppets split or blow out, but it's been at least 15 years since I last replaced a bad valve. I have to laugh at the "Tom's Way" Kleen-Rite video where he says to just use all the kits, don't bother with rubber parts. Problem is the three kits for a Cat 623 is like $450 when all the seals and backup rings for a full rebuild only cost about $70.

 

[OurTown]

I pressed the reset button six times which blows down one cycle each. After that it got up to pressure as good as it has been lately. (2 seconds or so) At this point I'm not convinced that the check valve is good. They are calling for rain Friday and Saturday so maybe I'll have a chance to remove and put some air to the check valve.

 

[OurTown]

I removed the check valve from the pump manifold and left it connected to the hose. Hit the rest button to get it to blow down and sure enough its pushing a little water! Now what CV should I buy and from where?

 

[MEP001]

I've had no issue with these, as long as they're the Teflon model:

Steel Body 20 GPM Check Valve with PTFE | Fluid Controls CV-800T

This Fluid Controls CV-800T check valve is constructed with stainless steel and has female 3/4" connections. Rated for 20 GPM and 3500 PSI.

www.kleen-ritecorp.com

 

[OurTown]

I've had no issue with these, as long as they're the Teflon model:

Steel Body 20 GPM Check Valve with PTFE | Fluid Controls CV-800T

This Fluid Controls CV-800T check valve is constructed with stainless steel and has female 3/4" connections. Rated for 20 GPM and 3500 PSI.

www.kleen-ritecorp.com

I saw that but we are running more than 20 GPM.

 

[OurTown]

I keep running across the General Pump CV but for some reason it shows that it has British pipe threads. When I do a Google search on compatibility of the threads some say they are but not good for high pressure connections.


https://www.kleen-ritecorp.com/p-22113-general-pump-ycv34fss-48-gpm-34in-check-valve-6500-psi.aspx

 

[JGinther]

I would lean toward installing a one inch valve on the outlet of a 3535. 3/4 valves with the pulsation from the pump and the high instantaneous flow often causes the internals to fail. What valve is currently on there? If that one lasted 20 years, I would go with it. Otherwise, I would go with a para-plate. I have had many failures of the fluid control valves mentioned when high flows are going through the valve. For low flows, they are great though. Did the manufacturer not use a large unloader with integrated check valve?

 

[OurTown]

I'm not sure what valve is in there because the label is not readable anymore and doesn't look like anything I found that is available now. It looks old and has been taken taken apart before. The regulator is the one I linked to earlier. I'm not sure if it has an internal check valve but it is plumbed off a tee that returns to the suction side of the pump. On the opposite side of the head there is a pulsation damper. Monday I'll see what Super Wash has available.

 

[JGinther]

That regulator doesn't have an integrated check valve. Depending on plumbing, I would probably replace the existing regulator with a general 5221 unloader. That way you get a new unloader/regulator, and also get the check valve needed. But the plumbing would have to be configured where the blowdown and all other solenoids etc is downstream of the unloader's check valve.