Grooved Ring 6.365-394.0

Watched your you tube video and it made the repair straight forward.

Invert pressure washer and remove four bolts (there's oil in the upper section to lube the bearings)
Split the pump halves and replace the seals.
Reassemble the halves and reinstall the pump to the bottom of the engine (ensure the upper section of the pump is still about 3/4 full of motor oil).
Snug up the four pump bolts.
Turn pressure washer right side up and allow time for the engine oil to drain back into the lower engine.
Connect water hose, pressure wand, and turn on the water.
Start engine (it may smoke a lot for a few minutes) and check for water leaks. Mine dripped some for the first few minutes then stopped after running the washer.

1 Break the cylinder head bolts (do not loosen or remove the bolts since pump oil will leak out)
2 Remove the bolts attaching the pump to the engine.
3 Slide the pump off the keyed engine shaft.
4 Place the pump upright and remove the cylinder head bolts.
5 Separate the two bronze plates (piston guidance and cylinder head)
6 I replaced the three "grooved rings" and the three oil seals. One of the "grooved rings" was obviously damaged and is presumably the cause of the water leaking. I thought this was the most difficult part of the job. The seals are pretty tight and putting the new ones in also requires patience. Removing the oil seals was assisted by a small weep hole on the back side of the piston guidance plate. I poked a small nail thru these weep holes that helped pop-out the oil seals. The new oil seals went in fairly easily. The "grooved rings" were easy to remove but difficult to install the new ones. Had to squeeze the edges to get the seals in which took some effort.
7 I changed the pump oil. The old oil had a milky appearance which I assume is due to some water mixing. Be sure to hold down the wobble (swash) plate as you tip the pump casing to drain the oil. There are ball bearings under the wobble (swash) plate that might dislodge from its retainer plate. The new oil (Karcher 10-40) was clear and looked like normal engine oil.
8 Reassemble the two bronze plates and place them on the pump casing. Note that pressure springs provide resistance and so you have to press the reassembled plates pretty hard as you reinsert the cylinder head bolts. Tighten the bolts so the oil doesn't leak out during reassembly.
9 Slide the reassembled pump on to the keyed engine shaft and tighten the pump mounting bolts. Snug up the cylinder head bolts. I put some grease on the engine shaft first.
10 The repair was successful. No leaks and no pressure pulsations. (Note that I had replaced the overload valve previously which had no effect on the pressure pulsations). In retrospect I would also replace the large o-ring between the pump casing and the piston guidance plate.

Took unit apart. Replaced bad parts and re-installed.

1) watched several (multiple times) You Tube videos to understand the inside workings.
2) worked at removing the Actuation Housing. I realized that the key was probably rusted, and with some lubricant removed the housing.
3) Had to get Karcher USA to email me the owners manual and parts lists. (very timely/responsive).
4) three different orders placed, after realizing parts needed replaced.
5) Did not understand when replacing shaft seals (pt no 6.365.393.0) if the groove was to be oriented up or down.
6) Same thing for groove ring (pt no 6.365.394.0)
7) Assembled with new parts, but water still spews out between the 2 housing halves.
8) Water mixed with oil is still present. I will need to disassemble, clean, and consider other part replacement. The PW worked fine with wand activation at the startup, but the water side seems to be leaking into the oil reservoir and forcing oil out. I was surprised to see behind the swash plate (wobble plate). May have to disassemble the to place the seal ring (pt no 7.367-018.0).

Replaced the o-ring and pressure springs

found 1 bad check valve
replaced all 3 check valves
replaced all 3 oil seal rings
replaced all 3 grooved rings (lip side out using a small screwdriver to get it in)
cleaned swash plate and bearings
put new oil (karcher 15 w 40 )
reassembled
cleaned and lubed unloader valve

1. Purchased all most likely parts likely to cause problem: valves, seals & springs.
2. Disassembled pump. No oil in wobble plate housing - only some water. (Probably piston seal?)
3. Cleaned housings, reused parts with carb cleaner. Added 15-40w oil. Reassembled & installed.
4. Works better than when I bought it, (was rebuilt unit.)
5. I found seals a little tricky to install as they are flared out & you'll probably try to use a screwdriver to install - careful, easy to damage seal.
6.Also, check the spill valve before you remove pump - it can cause erratic (as well as low) pressure.

I rebuilt the pump with the parts you suggested. Be careful with Karcher pumps. If you replace the nozzles with standard big box store nozzles they can cause this surging. That is what I recently did. Make sure you have the correct capacity nozzles before you rebuild a pump.

1. Disassemble pump
2. Inspect pieces and parts
3. Found some seals broken and dried
4. Order the parts
5. Clean and put the new spare parts per diagrams and videos
6. ensemble pump per pictures and hand sketches
7. Put new oil pump
8. Test pressure washer