I have an AR Pump model XTV 3G20, operated by a 5.5 gas engine and it was sold by NorthernStar. It was leaking out the pump head so I replaced the seals and packing but this had no affect on increasing pressure. Although I don't see any leakage out of the bypass when I open the nozzle I suspect the regulator/unloader valve might be the problem. I don't see what else could be causing this. I have a good water supply and the suction screen is clean. A visual inspection of the poppet valves didn't indicate anything wrong. The unloader/regulator valve is a 4 in 1 Northernstar part number 30315. I would like to use a rebuild kit but haven't been able to find one yet. Any thoughts or help on where I'm at and headed would be greatly appreciated.
Low Pressure
- Thread starter 688i
- Start date
mtngoat
Member
Unloder could be bad? Do you work in alot of hard water areas? Sometimes they get caked with mineral build up and all but stop. Are you pulling air from someplace-hose clamp? Could be your plumbing needs to be tightned up with some teflon tape. Internal O rings on ceramic plungers could be bad?
Not picking up a prime for some reason? Try force feeding the pump with a garden hose.
Take off feed hose to pump and hold the garden hose up to the pipe that feeds your pump if it doesnt pick up prime then somethings not rite.
Hmmmm could be lots of things anybody else wanna jump in here?
Where is Russ Johnson when you need him?
Not picking up a prime for some reason? Try force feeding the pump with a garden hose.
Take off feed hose to pump and hold the garden hose up to the pipe that feeds your pump if it doesnt pick up prime then somethings not rite.
Hmmmm could be lots of things anybody else wanna jump in here?
Where is Russ Johnson when you need him?
I'm not pulling air from anywhere cause I get a good steady stream from the nozzle. I'm not familiar with the internal ceramic plunger o-rings and my book states not to mess with the plungers if they aren't cracked or damaged. I'm afraid if I try to remove them they will break and they ain't cheap. The garden hose connects to a quick disconnect right on the pump head so I don't understand what you mean by force feeding unless you mean to take the strainer out. Do you know if they make a kit for the Northstar 4 in 1 unloader? Our water is hard but have disassembled the unloader and don't see any buildup.
Russ Johnson
Equipment Expert
mtngoat said:
In bed...even Superman needed to rest...lol
You say you don't see any leakage out the bypass? Are you bypassing to a tank? I'm not sure what you mean here. How do you see the bypass stream?
When you removed the valves, were all the o rings under the valves in good shape?
Are you getting any water in the oil?
Does the pressure pick up at all when you start the engine, or is it still at hose pressure?
Nothing like answering questions with questions, but this will help us narrow down the cause instead of "replace this, or this, or try this". I'll check back here later to see if I can help more.
The bypass is not to a tank just back to pump suction. I took the hose off to see if it was leaking when I pressed the nozzle and it was not. There was good flow when I turned nozzle off as I would expect. I did not remove the valve o-rings to check but will do that next. I don't believe I am getting any water in oil but will check again to make sure. Pressure picks up when I run the engine but not near what it should be. Thanks and will get back later with more answers to your questions.
Russ Johnson
Equipment Expert
Hey, 688i, while your at it, could you please fill out your signature? If you don't know how, here's a link to help. Thanks.
http://www.pressurewashinginstitute.com/board/upload/showthread.php?t=6109
http://www.pressurewashinginstitute.com/board/upload/showthread.php?t=6109
Me Again
I tried to do a signature but don't know if it will work this time or not. I have completely disassembled the pump head and unloader valve. Did not find any noticable problems. O-rings all looked good and put a little silicone on them before reassembly. Oil is good. There was no change in pump pressure. It picks up some when the motor runs but not much. It sprays approximately 20 feet with just hose pressure and about 35 or 40 feet with motor running. You can still hold finger in stream at nozzle head. The unloader valve is a 4 in 1, MV-570 sold by Northern. I really don't see how it works with a ball bearing for a seat and a flat flared head needle for a disc. It lifts up when you open the nozzle and shuts off the bypass. I noticed some dripping of water at the lower bypass nipple. Any suggestions would be appreciated because I am out of silver bullets unless the unloader is just plain worn out and this is not obvious. I forgot to mention one thing, i.e. the engine has a slight hunt to it but it steadys out if you move and hold governor linkage by hand slightly and the increase in throttle has no effect on pressure. Slight hunt comes back if you let go of governor leakage.
I tried to do a signature but don't know if it will work this time or not. I have completely disassembled the pump head and unloader valve. Did not find any noticable problems. O-rings all looked good and put a little silicone on them before reassembly. Oil is good. There was no change in pump pressure. It picks up some when the motor runs but not much. It sprays approximately 20 feet with just hose pressure and about 35 or 40 feet with motor running. You can still hold finger in stream at nozzle head. The unloader valve is a 4 in 1, MV-570 sold by Northern. I really don't see how it works with a ball bearing for a seat and a flat flared head needle for a disc. It lifts up when you open the nozzle and shuts off the bypass. I noticed some dripping of water at the lower bypass nipple. Any suggestions would be appreciated because I am out of silver bullets unless the unloader is just plain worn out and this is not obvious. I forgot to mention one thing, i.e. the engine has a slight hunt to it but it steadys out if you move and hold governor linkage by hand slightly and the increase in throttle has no effect on pressure. Slight hunt comes back if you let go of governor leakage.
Russ Johnson
Equipment Expert
Can you get a gauge? I'd be interested to see what the pressure does when you let go of the gun. You didn't by chance put the high pressure seal in backwards, did you? I ask because I have seen it happen more than once. No leaks...no bypass when the gun is squeezed....does the engine sound like it's being put under a heavier load before it peaks out and unloads? I have also seen a sheared crankshaft key do as you describe. So tough to fix from here, y'know?
By the way, your signature looks great. I really like your quote...so true.
By the way, your signature looks great. I really like your quote...so true.
If I had a sheared crankshft key would the ceramic pistons still move when you pulled the engine rope? When I pull the rope the pistons move in and out. I don't think their is much load on the engine. The gun jerks when you turn it on and off but there is no real noticable change in engine load. I know the seals are installed correctly. Thanks for your prompt response.
Russ Johnson
Equipment Expert
What size nozzle do you have on the end of the gun?
Does your machine have an easy start valve as well as the unloader?
Does your machine have an easy start valve as well as the unloader?
How do I determine nozzle size? Does it have the size stamped on it? I do not have any other valve on the discharge other than the unloader but it's called a 4 in 1 unloader what ever that means. This pump is 8 years old but has been used very little and looks like new. It has set idle most of the time in the garage. I thought it might have a cracked valve head cause it still has a few drips when running but not totally sure where the drip is coming from. If it does have a cracked head you can't see it visually. Would it be worth while to perform a liquid penetrent test on the pump head? I'm thinking if it is cracked it's internal and not visible. Your continued support is appreciated.
Russ Johnson
Equipment Expert
A few drips? From behind the brass head? Probably a cracked plunger. The nozzles should be stamped with the number...these are stainless steel nozzles, not a plastic adjustable, right?
Russ Johnson
Equipment Expert
Yes, with AR's using brown plungers, sometimes they're a bitch to see. If you want, take the pump off the machine, remove the dipstick and replace it with a pipe plug so the oil won't leak, and ship it to me. I'll check it over and let you know what's wrong with it.
I appreciate your offer but have not given up yet. Do you think cracks will show up better in the plungers if I spray water on them and use a magnifier glass? Is it possible the unloader is not working properly and this will cause low pressure? If I remove the unloader and run pump would this tell me anything? Does the unloader increase pressure, limit it or both depending on nozzle action? Thanks for your continued support.
Russ Johnson
Equipment Expert
Do you think cracks will show up better in the plungers if I spray water on them and use a magnifier glass?
You shouldn't need to get them wet, but a magnifying glass is a good idea.
Is it possible the unloader is not working properly and this will cause low pressure?
If the unloader isn't working properly, it would shoot water out the bypass while you are spraying, which you said earlier isn't happening.
If I remove the unloader and run pump would this tell me anything?
You can remove the unloader and hook the hose and gun direct...don't let go until you shut it back off. The water will have no where to go.
Does the unloader increase pressure, limit it or both depending on nozzle action?
The unloader will only increase pressure to the point that the nozzle builds it. Turning the unloader down will limit the pressure.
Thanks for your continued support.
It's no problem at all.
You shouldn't need to get them wet, but a magnifying glass is a good idea.
Is it possible the unloader is not working properly and this will cause low pressure?
If the unloader isn't working properly, it would shoot water out the bypass while you are spraying, which you said earlier isn't happening.
If I remove the unloader and run pump would this tell me anything?
You can remove the unloader and hook the hose and gun direct...don't let go until you shut it back off. The water will have no where to go.
Does the unloader increase pressure, limit it or both depending on nozzle action?
The unloader will only increase pressure to the point that the nozzle builds it. Turning the unloader down will limit the pressure.
Thanks for your continued support.
It's no problem at all.
I found something
I took the pump head off again for the fourth time and took a strong light and a magnifing glass and found a hair line crack in the ceramic plunger closest to the unloader valve. I took it off and it has two hair line cracks 180 degrees apart but not through wall. You can't even feel them with your finger or fingernail. Very hard to see but also noticed another small crack just on the end of the plunger. I did not see any on the other two so did not remove them. Can I replace just thie one and do you think this is my problem? Thanks.
I took the pump head off again for the fourth time and took a strong light and a magnifing glass and found a hair line crack in the ceramic plunger closest to the unloader valve. I took it off and it has two hair line cracks 180 degrees apart but not through wall. You can't even feel them with your finger or fingernail. Very hard to see but also noticed another small crack just on the end of the plunger. I did not see any on the other two so did not remove them. Can I replace just thie one and do you think this is my problem? Thanks.
Russ Johnson
Equipment Expert
Yes, one plunger can be replaced. Make sure you get the washers, o ring, and back up ring to go with it.
Questions
Would these tiny cracks open up and cause low pressure and slight drip from behind head while running? I only see a copper washer and an internal O-ring. Is there what you call a backup ring further inside pump on plunger bolt? I looked at the drawing and there is a washer behind the plunger so I guess I just need to pick it out. I am having trouble finding a single ceramic plunger with the o-ring, copper washer and other washer. They sell a kit with all of the stuff for three plungers and I have found a single plunger only. I am presently contacting vender to see if all parts for one plunger can be procurred. Before I spend any more money I would like some confirmation from you that these tiny cracks could cause the pressure to be low. Also do you have a recommendation for locating the single ceramic plunger and associated parts? Thanks again.
Would these tiny cracks open up and cause low pressure and slight drip from behind head while running? I only see a copper washer and an internal O-ring. Is there what you call a backup ring further inside pump on plunger bolt? I looked at the drawing and there is a washer behind the plunger so I guess I just need to pick it out. I am having trouble finding a single ceramic plunger with the o-ring, copper washer and other washer. They sell a kit with all of the stuff for three plungers and I have found a single plunger only. I am presently contacting vender to see if all parts for one plunger can be procurred. Before I spend any more money I would like some confirmation from you that these tiny cracks could cause the pressure to be low. Also do you have a recommendation for locating the single ceramic plunger and associated parts? Thanks again.
Last edited:
Russ Johnson
Equipment Expert
Yes, cracks in the plunger, no matter how slight appearing, can and will affect pressure, especially if you are seeing leakage.
Here are the parts you need for single plunger replacement:
1 - 1260100 washer - $0.43
1 - 1260120 plunger - $38.69
1 - 480480 o ring - $0.43
1 - 1260091 washer - $0.70
These are all list prices, your cost would be 25% off for a total of $30.19. This is a small order, too small for the minimum by themselves, but I can order them with my next stock order and ship them to you. I should have an order ready for AR on Thursday. Let me know if you want them.
Here are the parts you need for single plunger replacement:
1 - 1260100 washer - $0.43
1 - 1260120 plunger - $38.69
1 - 480480 o ring - $0.43
1 - 1260091 washer - $0.70
These are all list prices, your cost would be 25% off for a total of $30.19. This is a small order, too small for the minimum by themselves, but I can order them with my next stock order and ship them to you. I should have an order ready for AR on Thursday. Let me know if you want them.