310 pulsating on startup

[cbchevy4x4]

Ok I'm done beating this horse.

Problem, bay sits unused for 30 minutes when switched to hp, doesn't matter whether it's hot or cold water both gravity fed, pulsation occurs for 5 seconds. The longer the bay sits un used the longer the pulsation will occur.

Steps taken so far.

Inspected seals and valves...all ok
Swaped pumps between bays. Problem does not follow pump
Swaped unloader between bays. Problem does not follow unloader.
Checked inlets for air suction...nothing.
No water leaks on output side all the way to the bay.
No belt slippage.

It acts like the water in the hose is leaking out of the hose, as when weeps are activated esp overnight the problem does not occur.

I have disconnected both the inlet hose to the pump and the hp hose from the pump to unloader to see if water back flows out of the system going out to the bay. Nothing.

Have shut the bay down overnight left the wand on the floor over night when weeps are not going to see if water drains out that end. I'd see that on my cameras if so... again nothing.

What am I overlooking?

 

[Martins]

Whats the belt doing during pulsation? motor itself? belt slip?

 

[cbchevy4x4]

Whats the belt doing during pulsation? motor itself? belt slip?

No belt slip, motor is smooth...0 fluctuations.

 

[Martins]

No belt slip, motor is smooth...0 fluctuations.

If it seems like water loss swap main water feed to another pump and see if it moves/ swap another water inlet to that pump. i would say the pump needs rebuild but if the pumps not doing it in another location then id say thats not it. for some reason im leaning twords the motor itself? but just throwing darts

 

[MEP001]

There's a lot of air in the filter bowl. I'll bet it's the low pressure seals in the pump.

 

[cbchevy4x4]

There's a lot of air in the filter bowl. I'll bet it's the low pressure seals in the pump.

Thing is i have swapped the pump head from one bay to another and the problem doens't follow it, i would think if it were the LP seals it should follow the pump.

 

[2Biz]

This looks like a Mark VII pump stand and water is being restricted to the pump. It uses gate valves to control water flow to adjust flow for propper vacuum so soap and wax draws correctly into the pump. Try opening both hot and cold supply valves up all the way to see if the pump starts running right. Gate valves are notorious for rusting and twisting the gate stem off so you have no control. I redesigned my Mark VII and got rid of the original nightmarish plumbing they came up with. The only valve I have now is the Erie 2 way valves. No flow control valves needed.

If you want to learn more, you can check out a thread I started years ago on how I fixed the plumbing so it can now easiy be worked on!

(3) Modding an "Old" Mark VII Pump Stand | Car Wash Forum

 

[cbchevy4x4]

This looks like a Mark VII pump stand and water is being restricted to the pump. It uses gate valves to control water flow to adjust flow for propper vacuum so soap and wax draws correctly into the pump. Try opening both hot and cold supply valves up all the way to see if the pump starts running right. Gate valves are notorious for rusting and twisting the gate stem off so you have no control. I redesigned my Mark VII and got rid of the original nightmarish plumbing they came up with. The only valve I have now is the Erie 2 way valves. No flow control valves needed.

If you want to learn more, you can check out a thread I started years ago on how I fixed the plumbing so it can now easiy be worked on!

(3) Modding an "Old" Mark VII Pump Stand | Car Wash Forum

I have tested with fully opened valves, problem still occurs. I Have also swapped the pump inlet supply to another bay. Same thing happens, problem stays put and doesn't follow anything i swap. I have tested everything that you could think of, except of course what ever the problem is. Damn carwash gremlins.

 

[2Biz]

I will add, Mep is Correct about seeing air in the inline filter bowl....ANY air allowed to get into the pump will make it run like this. When you figure out how and why air is getting in the filter bowl, you will have found the gremlin!

 

[2Biz]

You might try taking a 5 gallon bucket and attaching a 1/2" barb fitting and hose and attach it to the pump. Fill the bucket and as long as the water level is above the pump inlet, should be a good test. You can push in the motor starter to do the test so you don't risk running out of water and you can see whats happening inside the bucket. If the pump pushes bubbles back into the bucket, you know you have a pump seal problem...If it runs smooth, it proves air is getting in the plumbing somewhere...

 

[MEP001]

I watched it again, and when the pump runs with pressure the water in the filter bowl "boils." When the pressure drops, it's clear. That indicates cavitation, and it also sounds like cavitation.

 

[Randy]

I've watched the video a number of times and I also see the water "boiling" inside the clear filter bowl. Your sucking in air somewhere. Can you post some more pictures of your pump set up. I'd like to see how it's al plumbed. Are all the other pumps plumbed the same way?

 

[2Biz]

Randy, it's an original plumbed Mark VII stand just like mine.

 

[I.B. Washincars]

Okay, I dealt with this a decade or so ago, and here's what's probably happening. Air is getting trapped in that big 2" PVC pipe. That bay is probably at the high point and that pump is going to get the gob of air before it gets it's water. I had the same pump stands (2) and as the one next to the water softener rusted away and started collapsing, I had a high point where the two stands were connected with a vinyl hose. Sometimes I could see an air pocket in the hose. It was always a bay adjacent to that joint that cavitated. Since my stands were on their last legs (literally, one had rusted off) I knew had to figure out a KY engineering fix. I ended up getting one of those valves that clamps on to a water line, like when installing an ice maker. I drilled a hole in the highest point in the pipe I could access and installed the valve with hose clamps wrapped around the PVC, to act as a vent for the trapped air. I just ran a small hose off the vent valve up the back of the stand, so it would be higher that the rinse tank. It worked great for a few years until I bought a used stainless steel ProLine system to replace it.

Before installing my "New" system, I eliminated those manifolds and a lot of other unnecessary plumbing, and each bay got it's own feed hose.

 

[OurTown]

my stands were on their last legs (literally, one had rusted off) I knew had to figure out a KY engineering fix.

I'm not sure about the cavitation issue but the rusted pump stand surely could have been propped up by a used bourbon barrel. I'm sure there were plenty around town.

 

[I.B. Washincars]

I'm not sure about the cavitation issue but the rusted pump stand surely could have been propped up by a used bourbon barrel. I'm sure there were plenty around town.

Actually, no. When I was a kid you could get them just for the asking. It's nothing at all now to have to pay $100 or more for one.

 

[MEP001]

It's nothing at all now to have to pay $100 or more for one.

They sell them at Home Depot, between $50 and $175 for half of one.

 

[2Biz]

Okay, I dealt with this a decade or so ago, and here's what's probably happening. Air is getting trapped in that big 2" PVC pipe. That bay is probably at the high point and that pump is going to get the gob of air before it gets it's water. I had the same pump stands (2) and as the one next to the water softener rusted away and started collapsing, I had a high point where the two stands were connected with a vinyl hose. Sometimes I could see an air pocket in the hose. It was always a bay adjacent to that joint that cavitated. Since my stands were on their last legs (literally, one had rusted off) I knew had to figure out a KY engineering fix. I ended up getting one of those valves that clamps on to a water line, like when installing an ice maker. I drilled a hole in the highest point in the pipe I could access and installed the valve with hose clamps wrapped around the PVC, to act as a vent for the trapped air. I just ran a small hose off the vent valve up the back of the stand, so it would be higher that the rinse tank. It worked great for a few years until I bought a used stainless steel ProLine system to replace it.

Before installing my "New" system, I eliminated those manifolds and a lot of other unnecessary plumbing, and each bay got it's own feed hose.

Good Idea on putting a vent/hose on the horizontal PVC pipes. Glad I don't have to screw around with the bad engineering of the original Mark VII pump stand any more...Mine has been trouble free for the last 10 years since I made the modifications...

But why is air getting in the pvc pipes? I'm wondering if cbchevy4x4 has figured out to put a pvc tee on his float valves to help eliminate air bubbles and sloshing in the gravity tanks. Could be a possiblity on how air is getting sucked into the horizontal pipes? Should be easy to see it happening if its the cause??

 

[cbchevy4x4]

UPDATE: All pumps are plumbed the same way. Not all plumbing to the stands are original as some modifications have been made over the years. Some of the suggestions for replumbing in the above other thread have been looked at and most were already on my "TO DO" list but this did give a good look at what the final product could look like. I did look at the main line running under the pumpstands to see if there were some how air entrampment within the pipe already as this is probably the highest point in the system. No air is visible but doesnt mean its not there. Float valves with-in tanks do have T's.

After performing the high tech bucket test the results were... no air back feeding from the pump inlet. Although i was getting air out of the bypass when trigger not pulled. I have replaced the unloader and quickly tested, thus far no issues with the cavitation. I think there may have been a problem with the seals of the bypass causing it to suck air when in bypass, most people do not keep the triggers pulled as they switch functions on the rotary swithc and i could see this being the cause as the air continuously recirculates until the trigger is depressed and expelled from the system through the HP hose. I am going to leave the bay shut down over night and test again in the morning as the problem usually shows up the longer the bay sits unused.

Hopefully i am saying its fixed...we will see.

 

[Randy]

What kind of regulator/unloader are you using? I just had to replace my last 40 year old Cat regulator, I put on a J. E. Adams RE7085 and it’s working fine. https://www.kleen-ritecorp.com/p-17...balanced-regulator-3-8-npt-2000psi-7-gpm.aspx