Hacking Karcher foaming attachment

A

ahains

New member
Received my karcher foamer attachment last week and played around with it a bit, not as "clingy" of foam as I had hoped.

I was using 1 fluid ounce of CG maxi suds to 10 oz water (bottle held about 11oz). It was quite sudsy, but it all ran off fairly quickly and didn't give me the several minute dwell I was hoping for.



I pulled off the pickup tube and bored out the passageway a bit that the venturi draws the soap through. My drill bits measured it at about 60 from the factory and I slowly worked my way up to 35. I don't know the units, some standard drill bit system I suppose. It was quite small from the factory.



This did give me a lot more draw, it emptied a full bottle in about one pass around the car instead of about two passes. But it still wasn't that clingy of foam. Next I sawed off the tip of the foamer so I could reach the venturi passage with my drill bit. Sawed off just after the passageway reached full diameter again (just before the nozzle looking end piece). I bored that out to about 50 IIRC (I knew I should've written the numbers down..).



End result - fairly high throughput of quite soapy mixture that does not cling to my car very well.

I consider however that I have not failed but rather learned two ways to modify my foaming attachment for operation that I do not like :)



So, my next shot in the dark is going to be to fill in the venturi with JB weld and bore through again. I'm going to go with a smaller than stock bore through the venturi (my smallest drill bit of 60, I believe 55 was stock). For the vertical bore for the passageway that draws in the soap, I will start small again at 60 and slowly work my way back up. My hope is that I'll end up with a slower flow overall with greater soap ratio, probably with 60 through the venturi body and ~40 in the soap drawing passageway.



I don't think that the autobrite lance contains any black magic, I assume it is just simple mechanics at play and I just need to understand better how to control the variables. The only other thing I can think of is if there is some turbulence introduced in their system somehow, like a passageway with ridges or spiraling flute.



Anyone with insight in this stuff have any tips on how to get the results I'm after?
 
Try two ounces of shampoo. :)



I believe that the Autobrite (a.k.a. Cam-Spray) attachment also brings in quite a bit of air downstream of the soap pickup tube/venturi. I think it's the air that makes it so effective at creating the thick foam.
 
I guess I didn't start with more soap because I had a preconceived notion that the Karcher would be substandard. There are some comparison photos from a guy in this thread:

Want to foam? What hardware? - Page 2 - Detailing World

The autobrite definitely has a thicker foam at its medium setting, but perhaps the Karcher could be workable. I'm adverse to paying ~$90 to get an autobrite (including shipping) if I can get this to work in any fashion.



I'm trying to imagine what I could do to introduce more air into the mixture after the soap pickup. Do you think I could just drill a small breather hole at the midway point to the venturi, right by the soap pickup? There is already a plugged passageway on either side of the foamer, right at the midway point (right by the soap pickup). I was wondering what those were for, I assume they are a manufacturing artifact. But in any case it would make it very easy to use my smallest bit to punch through there. Sounds worth a shot since I'm already getting pretty invasive with this experiment. I should have ordered two Karcher attachments originally to save on shipping, in case I completely ruin this one ;)

It was like $7 shipping on the $15 attachment..
 
SuperBee364,

I see from your previous posts that you have a cam-spray. Looking at it and the autobrite, I'm wondering if that adjustment wheel is just like a needle valve. Have you had yours apart? Or would you be willing to unscrew that knob to see if that is all it is? If so, drilling a tiny breather hole into mine may be just what I need to try.

Thanks!
 
ahains said:
SuperBee364,

I see from your previous posts that you have a cam-spray. Looking at it and the autobrite, I'm wondering if that adjustment wheel is just like a needle valve. Have you had yours apart? Or would you be willing to unscrew that knob to see if that is all it is? If so, drilling a tiny breather hole into mine may be just what I need to try.

Thanks!
Click to expand...



I'm quite sure it's a needle valve type of adjustment to control the soap pickup ratio, but I've never taken it apart. Honestly, since it was so expensive, I haven't had the urge to take it apart. It has stopping points at max ratio and at min ratio, so taking it apart isn't as easy as just unscrewing it. Don't think I really want to try and take it apart, sorry. :) Seems like everytime I have something that works really well, then take it apart, it never works as good when I put it back together again.
 
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