Question about Karcher 2500 PSI Pressure Washer

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How do I clean the unloader valve on a Karchner model G2600VH Cannot get steady pressure from the outlet of the nozzel have clean filter checked for leaks and replaced all nozzels still having issue with flux in pressure.

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  • orourkeej May 11, 2009

    I have the same problem and am also looking for a fix. Pressure is fine if I shut off engine and then restart but if I let go of the trigger and then try to reengage the pressure washer I get only a low pressure flow.

  • Anonymous May 12, 2009

    Karcher told me to remove unloader and clean and regrease and re-install. My was clean when I took it out, I still have the same problem when done. I believe it is a marginal design when I compare it to other makes. It has two sets of "O" rings on the valve and they do not seem to manage the high pressure bypassing the outlet to nozzle like I think it is supposed to... I have asked Karcher for further action but have received no reply yet, Mine is only a year old --

  • Anonymous May 16, 2009

    Same problem same answer from Karchner. They told me there were only two bolts holding the valve. Is it the brass at the end of the pump? If so mine has three bolts. I don't want to screw the thing up worse than it is. Sounds like a trend with this problem.

  • Anonymous May 16, 2009

    I found the valves. They were both clean. Restored to service with the same results. Contacting Karchner again.

  • Anonymous May 19, 2009

    Removed the valves again and greased them with Lithium grease. Unit is now working. For how long who knows. Have not heard from Karcher as yet. They obviously have a problem.

  • lwc1250 May 20, 2009

    the moter doesn't want to kick in. if you take off the pressure nozzle, pull the trigger it kicks in. you then can replace the pressure nozzle and use with pressure untill you release the trigger.

  • Anonymous May 21, 2009

    Local service rep for Karchner said they use NAPA Sil-Glyde part number: 765-1351. Removed the unloader valve cleaned again and applied this compound. Washer is now working. I hope this helps you guys. We will see how long it continues. If this is the fix it only takes 10 min. to fix.

  • sum1x May 22, 2009

    I have had the same problem for over a year . I have replaced the pressure hose, tried a couple of different nozzles, tried flushing the hoses and nozzles with air, replaced the O rings, put the old old rings back, cleaned the screen and washers for the water inlet, changed the rubber washer in my garden hose, monitored the water pressure in my home as I used the power washer, clamped the soap supply hose, unclamped the soap supply hose and emersed the other end in water, tried readjusting the setting on the sprayer nozzle, and even used teflon tape on all the hose connections. The best result has been up to three or four minutes of steady pressure before the intermittent on and off pressure resumes. Honda has a great engine. It starts everytime.That really helps to stay calm when trying to use the washer as it intermittently provides a pressure washer function.

  • Bobwojo Aug 16, 2014

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I am waiting for the mfg to provide me details on how to clean the unloader valve at this time.

Posted on Apr 29, 2009


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1 Answer washer seems to be locked up with pressure which is locking the flywheel. The gun trigger no longer releases the water pressure, and I don't know how to safely relieve the pressure. I

Your pressure washer is equipped with a "unloader valve". This is the device that routes the water into a by-pass loop when you release the trigger. Something has gone wrong inside causing the valve to not spring into the unload position. You can take it apart and see if you can discover what is going on. The most likely thing is that a bit of water still in it froze this winter and destroyed either replaceable seals or distorted the valve body (which is not repairable). On these little homeowner pressure washers, the best place to get parts is usually through the owners manual that came with it, or Karcher may have a web site set up for this. Also there is the possible resource of a pressure washer distibutor, which you would find in the yellow pages. They usually concentrate on commercial pressure washing equipment, but sometimes getting parts or pumps through them may be easier.

Feb 26, 2012 | Karcher G 2600 VH Gas Pressure Washer

1 Answer

I have a Karcher G2500HT. When I pull the trigger the pump will not engage. I pulled the pump off, checked the seals, and cleaned the screen. When I put it back on there was no leakage but the pump...

I would have to agree with your service department. The unloader valve works like this, When you press the trigger it closes and allows the water to build pressure through the pump. When you let off the trigger the valve opens and by-passes the water through the pump so you don't damge the pump. If this valve is sticking and remaining open the pressure will not build. You can remove this valve and clean relubricate with white lithium grease just a coating and this should clear up your problem. Check the port that the valve sits in and if you see gunk just clean with carburetor cleaner and blow it out with air compressor. A new unloader valve can cost between $40.00 - $60.00. Try to clean first before you buy a new one. The valve is usually located near the outlet that you connect your pressure hose to. If you can't find it go to and do a parts look up for your machine and you will see where this valve is located. Hope this helps.

Jul 20, 2011 | Karcher 2500 PSI Pressure Washer

2 Answers


I have same model with same problem. Tried the easy fixes:
unloader valve lube and clean, inlet water sufficient, and nozzles and hose are fine. Broke down pump and called for parts (about $50 for 3 inlet valves and some seals) hopefully this will fix it. Mine has been used in my business pretty hard for a few years, so not bad.

Jun 11, 2011 | Karcher G 2600 VH Gas Pressure Washer

1 Answer

Pressure off and on every few seconds with my karcher 3000BH

hi there rjcomer2

here is web site for parts

sounds like you have a unloader valve problem or a crack in the pressure manifold housing between pressure outlet and unloader valve assy allowing unloader to cycle on/ off

or some dirt trapped in the unloader valve seat , make sure you have good supply of water - ie good flow from tap to pump

try cleaning unloader 1st and fitting in line tap filter

hope it helps


May 20, 2011 | Karcher 2500 PSI Pressure Washer

2 Answers


It sounds like the unload valve might be clogged up. Try taking it off anf cleaning it back up. If the compressor is older or has had a lot of use sometimnes when the rings wear oil and gunge will get into the valve and gum it up. good luck

Mar 10, 2011 | Air Tools & Compressors

2 Answers

Can the pump be replaced? If so can it be a "do it

yes, the pump can be replaced but I would recommend trying to repair the pump first, see this link to repair the unloader valve, 9 times out of 10 this is the only issue with the pump

Nov 05, 2010 | Karcher G 2600 VH Gas Pressure Washer

1 Answer

Coleman model APW-120 May have frozen while stored over winter the unit is new but water was not completly removed before storage. Problem motor runs continuosly but there is no water pressure I have...

Whar has happened is that your unloader / bypass valve is sticking. This is due to minor corrosion and having water in the unit over the winter. Most of the time they will sanp out it if you do the following:

Add 3 - 4 oz of oil into the water supply connection and briefly and I mean very briefly switch on the unit then right back off. Add more oil to the water supply connection and then let it sit overnight.

Then next day turn the unit on briefly and let it sit another 30 minutes. After this you connect all hoses making sure to purge the air our of the supply hose BEFORE you connect the to the unit. Then once you turn the unit on rapidly trim cycle the wand trigger. Your goal here is to cause a water hammer of the unloader / bypass valve to get the spring and cupped seal to move in the housing. Pause briefly and see if pressure builds then fan the wand trigger again. This can take a few minutes to get it to work but the routine of pausing waiting momentarily and rapidly tripping the wand trigger is what should get the unit going again.

If this does not work you will have to take the unit apart dis-assemble the unloader / bypass vavle on the output side of the pump and remove the corrosion on the spring and the housing.

Once your done cleaning up the bypass unloader valve before you put it back in the housing place a liberal amount of Lubriplate #105 White Grease on the spring and inside the housing on the mating surfaces. (#105 white grease is available at any Auto Parts store. It is in a 3 - 5 oz plastic tube)

Re-assemble the unloader / bypass valve an it should work like a champ.

Thanks for choosing FixYa.


Sep 16, 2010 | Coleman Powermate DuraBuilt 1400 PSI...

1 Answer

Single cylinder/oil free 5.5hp 30gal will fill tank when started with tank empty. When tank pressure is bleed off motor attempts to start, humms and kicks breaker.

If the unloader is not working properly the motor cannot overcome the head pressure. Two things to check. Make sure tank check valve is not leaking. Easy test. With pressure in tank, unplug the compressor from outlet and remove discharge hose at tank and listen for leak or spray soapy water. If leaking replace valve or try to clean debris from valve seat. If not leaking then problem is most likely at pressure switch unloader valve. Follow 1/4 inch hose from checkvalve at tank to connection at pressure switch. When pressure switch reaches cutoff pressure the switch opens the contacts and moves small tang against valve stem to release air from discharge hose. Check for proper function and repair as needed. Good luck.

Aug 18, 2010 | Craftsman Air Tools & Compressors

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Can't get water to come threw nozzel

Sounds like you may have some calcium buildup in the hose, gun or unloader. Take the unloader (where the hoses hookup) apart and clean away the deposits. This should solve your problem.

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Pressure washer, john deere 3000 psi, honda engine

It sounds like your intake is plugged with debris. What usually happens is a water hose that has been laying around will get various stuff in it -- dirt, grass clippings, small insects (and whatever they take into it nest building). These days most homeowner pressure washers do not have a proper inlet filter, but just a screened hose washer like on a washing machine. The unloader valve can cause pressure variance, but usually not in the manner that you described. The pump is being "starved" for input water. Just use a pair of needle-nose pliers and pull out the screen and clean it or replace it.

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