TL; DNR * A relatively low pressure of 2340 'cleaning' units good for light-duty jobs * Easy to use, but only when the hoses and power cord are kept untangled * Water must be purged in winter; use antifreeze protection when freezing * Even with winterization, its pump cracks within 1-2 years in 1 of 10 units * A broken unit under warranty may be replaced via the exchange program UPDATE By March 2021 the short-life issue of some K3 pumps still remains a matter of concern. ____ ORIGIN Kärcher GmbH is a German company with a North American subsidiary in Colorado. This K3 Follow-Me washer is made by a subsidiary in Changsu, China; it is destined only for the U.S. and Canada markets, as I could not find it in the Kärcher websites for other countries, which are accessible via the company main international website. (In other world regions, such as Europe, the four-wheel model K4 washer --a brand name that designates a totally different model than in the U.S. or Canada-- has a look somewhat similar to but is a much better designed and more expensive washer than the K3.) ASSEMBLY It has two steerable front wheels, each with twin rollers, and two fixed rear wheels. The latter are mounted by simple hand pressure until clicking in place, but the former need a forceful approach because the C-ring in the wheel's metal post makes it very hard to push the post in. I placed the (dry) unit, undercarriage up, on two sofa pillows with the handle in the middle of them, inserted a 1"-thick piece of wood in the space between the twin rollers of the wheel (see my first figure), and hammered the wood until the wheel was mounted. You may have to hit harder and a few more times than you might expect. OPERATION The Owner's Manual is well illustrated and written in concordant English, Spanish and French, and has important instructions for first-time use and storage of the device. Kärcher offers a non-transferable, limited warranty of 2 years for the motor, pump, and structural and electrical components (see below). 1. PRESSURE. Kärcher claims a maximal water pressure of 1800 PSI at the nozzle and a water flow rate of 1.3 GPM, resulting in 2340 nominal "cleaning" units -- in practical terms, these units translate into a light(ish) residential duty and casual use. Keep in mind that the actual force of the pressurized water jet on a surface depends on the nozzle geometry and distance to the surface. 2. WINTERIZING. The washer must be purged of all water for its winter storage and Kärcher recommends its silent video "Kärcher Hochdruckreiniger winterfest machen" [winterizing Kärcher pressure washers] in Youtube to learn how it is done. Though not mentioned there, in cold climates you should fill the pump system with an antifreeze protector before freezing develops for protecting seals and valves. The company sells its Pump Guard antigel, claimed to help protect down to -25°F [-32°C]. RESULTS I used the washer for light and medium duty jobs on spring and summer during its first year, when it performed well but for the annoying tangling of both the 35-ft power cord and the 15-ft high pressure hose, which notably detracts from the convenience of the follow-me capability of the K3. It was valuable for cleaning brick walls. The perimeter of our house lot is fenced by brick walls; dirt and mold (a result of hot humid days, and the water irrigation system, especially in the north-facing walls) darken the bricks, and eventually require cleaning. My second figure shows the before and after results from a part of the brick wall facing the street's sidewalk: the wall segment to the left of the pillar and the pillar itself were pressure washed, whereas the segment to the right of the pillar was not. In mid-Autumn, I fully purged water from the device, filled it with the Kärcher antigel pump guard per the instructions printed on the bottle, and stored it in a leveled horizontal place inside an unheated garage. The annual *extreme minimum* temperature where we live is between 0 and 5°F in winter (USDA plant hardiness zone 7a), but in the winter of 2018 the extreme minimum was of only 30°F. Thus, the protected device ought to have been totally safe and ready to work the next year. Alas, it was not. In mid-Spring I prepared it for its first use of 2018, and after 10 minutes or less of working, the water output suddenly became almost nil. As seen in my third figure (whose inset shows the antigel pump guard I used), removing the high-pressure hose and the spraying gun from the unit did not improve the output. The cause was a copious *leak* from the bottom of the washer, shown in my fourth figure. This was due, as I found later when taking apart the machine, to a crack in the plastic manifold of the pump system. The K3 has a wobble-type pump made of a material that the company calls N-cor, which is a hybrid made of glass fiber and a synthetic polymer. Wobble pump systems cannot be economically replaced. Perhaps because of this, Kärcher offers a replacement via an exchange program; the replacement unit's warranty lapses on the termination date of the old unit. The Kärcher service agent was easy to work with, and I received a replacement unit seven workdays after emailing the required documentation. The new device had all the signs of an unused unit, and came in a new packing box (to judge from its condition and its still unopened push-in hand slots to carry the box). Rather than relying simply in its winterization, the unit is kept in a heated storage room during winters. _____ THE CHANCE OF GETTING A SHORT-LIVED UNIT It is disappointing that even with proper care the pump system breaks down so easily with little use. Mine was not an isolated case. At the time of this writing, the only comment to the Youtube's video is from a woman complaining in German that she has "now four dead Kärcher" that "have always died relatively quickly." (After my initial review mentioned that, Kärcher responded to her saying they would like to know what were the frequent defects. Seriously.) More ignominiously, of the 22 K3 reviews in the Kärcher's U.S. website dated between 2017 and 2018, only 4 were positive while 18 were negative. (Other, much older reviews in that site were ignored as they had been transferred from other sites). This is a high failure rate (85%) but the sample size is too small to draw firm conclusions, except that early failures are *not* rare. This Amazon page, however, provided a better sample size. When I bought the unit in May 2017, 7% of the reviews [28 out of 399] complained of similar leaks by the first or second annual season of use. In May 2018, 7.5% [47 out of 620] complained of the same problem even though the total number of reviews had increased by a factor of 1.5. In November 2018, about 9% [62 out of 693] complained of leaks, and in May 2019 about 12% [91 out of 737] complained of early leaks despite that the total number of reviews had nearly doubled. This is a remarkable stability of the fraction of early pump-failure complaints over two full years, of almost 1 in every 10 units. By itself, the stability seems to exclude random 'lemon' unit cases during manufacturing, or an improper winterization by the users. From the viewpoint of manufacturing reliability analysis, this points much more to an issue of weak materials, or production flaws, vis-à-vis the absence of *proper screening* (such as doing a burn-in screen for electronic products) to avoid what in manufacturing is called the infant mortality stage of product failures. Be as it may, what the stability predicts is that one has a chance of about 1 in 10 of receiving a very short lived product when buying a K3 made with the same process and materials as those used by the company's Chinese subsidiary. Kärcher should take a very hard look at these early failures pointing to the decline of a once reputable manufacturer. .
