Zilla Coolant Redux

As I noted a while back, while I was pleased with the general concept and execution of the Nalgene water bottle as coolant reservoir, it had sprung a significant leak shortly after installation. Soon therafter the leaking increased heavily, draining approximately 1L of coolant in just a few hours. After inspection it quickly became clear that the bottle itself was destroyed- the mechanical forces on it from the bung in the bottom and the clamping forces from the mounting clamps were too much for the tough but brittle polycarbonate bottle.


I decided to redo a similar setup, but change a few elements based on this experience…


I picked up a new bottle, one of the soft, more flexible white plastic style ones. I mounted it with a foam tape layer under the mounting clamps. I reinstalled the hose barb in the bottom using aquarium RTV silicone, and placed the bung with the bottle and pump in place to mimimize stressing the fitting. This bottle is slightly less tall than the old one also, so the tubing connecting it to the pump is longer and more flexible. I also elected to use a thinner wall tubing. I reinstalled everything and it looks promising. I hope it will just work.


As a side note- I was finally able to acquire the video taken three weeks ago when I did the final hook up and test drive in the car- I will be editing it shortly. I am working on loose ends, as well as the charging system. I am also trying to figure out exactly how I’m going to register it, I would like to have it be driveable as soon as possible!!

Posted on June 8, 2009 at 10:29 pm by Henry · Permalink
In: EV Miata

3 Responses

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  1. Written by AcuteAero » An (almost) Year at AcuteAero
    on February 17, 2010 at 1:31 am
    Reply · Permalink

    […] The EV coolant bottle struggle- with two flavors of Nalgene water bottle. Good thing REI’s right around the corner. June 2009 […]

  2. Written by Pat Mackey
    on March 15, 2010 at 9:41 am
    Reply · Permalink

    Do you really need coolant in your Zilla?
    I had leaks in my system too, and decided to run it dry as a test and found my temp gauge hardly moves in my 4 mile freeway trips to work. Plus I once had to return it to Omar once and he complained there was moisture inside – maybe a leaky water jacket was to blame? So, my Zilla is now 100% air-cooled.

    • Written by Henry
      on March 15, 2010 at 9:53 am
      Reply · Permalink

      I may not really, I haven’t put enough miles on the car to really get a feel for it. It’s a relatively lightweight car, the average load is probably not that high on the controller. I know of a Zilla being used on a motorcycle that is passively cooled, and when Otmar was manufacturing the Zilla he tested them in his 914 without coolant. On the other hand the Optima batteries are good for 1000 amps, and most importantly the system is done and works fine now… so what gives. I doubt that your water block leaks, it’s a very simple design- I’m more worried about water intrusion on my Zilla. I suppose the Zilla is temperature protected so it’s not dangerous to run it without water- if it’s not overheating and shutting down it’s probably just fine.

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