Karcher Pressure Washer - Pulsing
Discussion
I have a trusty Karcher 6.91 pressure washer which I have had for what must be around 15 years.
With it being an older model the majority of parts are metal and it has been pretty reliable over the years with only a few replacement parts needed.
Over the past few weeks it has developed an issue where when not in use, but still turned on, it starts to pulse on and off.
When in use its absolutely fine with the motor running smoothly and no pressure issues.
I have stripped the machine down and cleaned everything up, changed the oil, replaced the capacitor and cleaned the filter all without resolving the pulsing issue. I have also tried different lances and hose connectors and there are no leaks or blockages.
Short of taking it to my local Karcher repair centre for them to have a look over it, any advice on what it could be?
With it being an older model the majority of parts are metal and it has been pretty reliable over the years with only a few replacement parts needed.
Over the past few weeks it has developed an issue where when not in use, but still turned on, it starts to pulse on and off.
When in use its absolutely fine with the motor running smoothly and no pressure issues.
I have stripped the machine down and cleaned everything up, changed the oil, replaced the capacitor and cleaned the filter all without resolving the pulsing issue. I have also tried different lances and hose connectors and there are no leaks or blockages.
Short of taking it to my local Karcher repair centre for them to have a look over it, any advice on what it could be?
Mine does it too - cant remember what model it is but its done it from new.
This may help
https://www.pistonheads.com/gassing/topic.asp?h=0&...
Also, AI gives some options
AI Overview
A Karcher pressure washer pulsing or surging during use is often caused by a few common issues. These include air in the system, clogged nozzles or filters, or a faulty unloader valve. It's also possible that there's a leak or the pump seals are worn.
Here's a more detailed breakdown:
1. Air in the System:
Air can enter the system through leaks or improper startup procedures.
To fix, ensure the water supply is turned on fully before starting the pressure washer and run the water through the hose and nozzle until a steady stream is achieved.
2. Clogged Nozzle or Filters:
Debris can accumulate in the nozzle or inlet filter, restricting water flow and causing pressure fluctuations.
Clean the nozzle with a nozzle cleaner or a small wire.
Inspect and clean the inlet filter.
3. Faulty Unloader Valve:
The unloader valve regulates water pressure. If it's malfunctioning, it can cause the pressure to fluctuate, leading to pulsing.
Check the valve for damage or debris. It may need to be adjusted or replaced.
4. Leaks:
Inspect the high-pressure hose, spray gun, and connections for any leaks. These can cause pressure loss and pulsing.
Repair or replace any damaged components.
5. Worn Pump Seals:
Pump seals prevent leaks and maintain pressure. Worn seals can allow air to enter the pump, resulting in pulsing.
Replacing the pump seals is a more complex repair and may require professional assistance.
Troubleshooting Steps:
Check for leaks: Inspect all hoses, connections, and the spray gun for leaks.
Clean the nozzle and filters: Remove any blockages that might be restricting water flow.
Ensure proper water supply: Make sure the water source is adequate and the hose is connected properly.
Inspect the unloader valve: Check for any damage or debris that might be interfering with its operation.
Bleed air from the system: Run the pressure washer with the trigger pulled until a steady stream of water is achieved.
This may help
https://www.pistonheads.com/gassing/topic.asp?h=0&...
Also, AI gives some options
AI Overview
A Karcher pressure washer pulsing or surging during use is often caused by a few common issues. These include air in the system, clogged nozzles or filters, or a faulty unloader valve. It's also possible that there's a leak or the pump seals are worn.
Here's a more detailed breakdown:
1. Air in the System:
Air can enter the system through leaks or improper startup procedures.
To fix, ensure the water supply is turned on fully before starting the pressure washer and run the water through the hose and nozzle until a steady stream is achieved.
2. Clogged Nozzle or Filters:
Debris can accumulate in the nozzle or inlet filter, restricting water flow and causing pressure fluctuations.
Clean the nozzle with a nozzle cleaner or a small wire.
Inspect and clean the inlet filter.
3. Faulty Unloader Valve:
The unloader valve regulates water pressure. If it's malfunctioning, it can cause the pressure to fluctuate, leading to pulsing.
Check the valve for damage or debris. It may need to be adjusted or replaced.
4. Leaks:
Inspect the high-pressure hose, spray gun, and connections for any leaks. These can cause pressure loss and pulsing.
Repair or replace any damaged components.
5. Worn Pump Seals:
Pump seals prevent leaks and maintain pressure. Worn seals can allow air to enter the pump, resulting in pulsing.
Replacing the pump seals is a more complex repair and may require professional assistance.
Troubleshooting Steps:
Check for leaks: Inspect all hoses, connections, and the spray gun for leaks.
Clean the nozzle and filters: Remove any blockages that might be restricting water flow.
Ensure proper water supply: Make sure the water source is adequate and the hose is connected properly.
Inspect the unloader valve: Check for any damage or debris that might be interfering with its operation.
Bleed air from the system: Run the pressure washer with the trigger pulled until a steady stream of water is achieved.
Yeah, its got a leak somewhere. Either leaking externally (drips!) or back past internal seals.
Either live with it and turn it off quickly when not in use, or strip and rebuild it with new seals etc.
What model/age is it?
The bigger older 'professional' units have an unloader valve rather than a pressure switch. So presumably its not actually like 25yo like my Karcher 411.
Either live with it and turn it off quickly when not in use, or strip and rebuild it with new seals etc.
What model/age is it?
The bigger older 'professional' units have an unloader valve rather than a pressure switch. So presumably its not actually like 25yo like my Karcher 411.
dhutch said:
Yeah, its got a leak somewhere. Either leaking externally (drips!) or back past internal seals.
Either live with it and turn it off quickly when not in use, or strip and rebuild it with new seals etc.
What model/age is it?
The bigger older 'professional' units have an unloader valve rather than a pressure switch. So presumably its not actually like 25yo like my Karcher 411.
It's a K6.91, probably around 15 years old now but one of the good ones with cast aluminium parts.Either live with it and turn it off quickly when not in use, or strip and rebuild it with new seals etc.
What model/age is it?
The bigger older 'professional' units have an unloader valve rather than a pressure switch. So presumably its not actually like 25yo like my Karcher 411.
I have stripped it down again today and visually everything looks fine so i'll have to admit defeat and put it into a Karcher repair centre. No point trying to trouble shoot further and replace parts/seals which may well be ok.
My local one is £45.00 for diagnostics which doesn't seem too bad.
s-x-i said:
It's a K6.91, probably around 15 years old now but one of the good ones with cast aluminium parts.
I have stripped it down again today and visually everything looks fine so i'll have to admit defeat and put it into a Karcher repair centre. No point trying to trouble shoot further and replace parts/seals which may well be ok.
My local one is £45.00 for diagnostics which doesn't seem too bad.
Fair enough. Nice unit.I have stripped it down again today and visually everything looks fine so i'll have to admit defeat and put it into a Karcher repair centre. No point trying to trouble shoot further and replace parts/seals which may well be ok.
My local one is £45.00 for diagnostics which doesn't seem too bad.
Hopefully they can sort you out.
Keep us posted!
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