Hello and such,

The coolant tank on my and other cars I find to be very unsightly. While there are aftermarket tanks available, I can't justify the price tag for what is essentially a cosmetic upgrade (although a more compact or better placed overflow tank could make a car easier to work one). So I decided to make my own!

Materials

1. 20 Oz CO2 Tank
2. Fuel Line
3. A/N Fittings
4. Pipe Plug

Tools

• Various grit sandpaper (80-1500)
• Buffing wheel
• Buffing compound
• Thread Taps
• Drills
• Lathe (Optional)

Design Theory

Much of my design was decided based on what I had available. My main goal was to produce a well made and aesthetically pleasing component, for a low cost (in this case all I had to buy was the pipe plug to cap the top). As it turns out, CO2 tanks that are commonly found in various sizes on mid-range paint ball guns make exceptional tanks for nearly anything. They are able to withstand high pressure, being made out of aluminum they are easy to modify and polish wonderfully, and they are CHEAP. While I could have used standard bronze pipe fittings with no issue, I had anodized A/N fittings laying around and I prefer the look of them. The fuel line was also laying around and seemed perfect for the application, but if this turns out to be an issue I can easily purchase different line to suit. On the standard tank a siphon is used to fill and drain the bottle as needed by the cooling system, I opted to instead just have to fill point on the bottom of the bottle, effectively doing the same thing. Additionally the tank was translucent so you could see the fluid level, but on the bottle I made I needed a clear piece of hose attached to the side to use as a level gauge. Additionally because I was no longer using the top as a fill point, I decided to just put a threaded pipe plug on top, leaving it as a place to manually add coolant if needed.

Build

First I removed the valve from the top of the bottle, it just threaded off with a wrench. I used a vice with a cloth wrapped around the bottle to avoid gouging the bottle. This is what the valve looked like when removed:
http://www.flickr.com/photos/mathizarthegreat/8570887935/http://www.flickr.com/photos/mathizarthegreat/8570887935/ by http://www.flickr.com/people/mathizarthegreat/, on Flickr

The bottle with valve removed:
http://www.flickr.com/photos/mathizarthegreat/8571982900/http://www.flickr.com/photos/mathizarthegreat/8571982900/ by http://www.flickr.com/people/mathizarthegreat/, on Flickr

Once all hardware on the bottle was removed I used a wire wheel on a bench grinder to remove the powder coating on the bottle. This actually took the longest of any step, as power coating is very, very tough and took several passes to remove. Be careful not to push to hard as the wire wheel will wear into the aluminum if you are not careful. This is the bottle after removing the powder coating.
http://www.flickr.com/photos/mathizarthegreat/8571934804/http://www.flickr.com/photos/mathizarthegreat/8571934804/ by http://www.flickr.com/people/mathizarthegreat/, on Flickr

Now would have been an idea time to drill and tap all the holes for the various fittings I would need to attach, but instead I began the process of sanding the bottle. To assist I chucked the bottle up into a lathe and then held sand paper against it to quickly sand the bottle. I highly doubt this practice even remotely approaches safe, and do not recommend doing it. DO NOT DO THIS:
http://www.flickr.com/photos/mathizarthegreat/8570840633/http://www.flickr.com/photos/mathizarthegreat/8570840633/ by http://www.flickr.com/people/mathizarthegreat/, on Flickr

To sand I worked my way from 80 grit to 1500 grit roughly doubling the grit each step. This is it after a fair amount of sanding, notice the stem of the bottle is not polished as well, this is because I chucked it into the lathe from that point and could not sand it easily. Another reason why using a lathe for this purpose is probably a bad idea:
http://www.flickr.com/photos/mathizarthegreat/8570840579/http://www.flickr.com/photos/mathizarthegreat/8570840579/ by http://www.flickr.com/people/mathizarthegreat/, on Flickr

After sanding I then put a buffing wheel on the lathe and began polishing:
http://www.flickr.com/photos/mathizarthegreat/8570840539/http://www.flickr.com/photos/mathizarthegreat/8570840539/ by http://www.flickr.com/people/mathizarthegreat/, on Flickr

This is after polishing. I began to drill and tap the threads out to what I needed:
http://www.flickr.com/photos/mathizarthegreat/8571934514/http://www.flickr.com/photos/mathizarthegreat/8571934514/ by http://www.flickr.com/people/mathizarthegreat/, on Flickr
http://www.flickr.com/photos/mathizarthegreat/8571934620/http://www.flickr.com/photos/mathizarthegreat/8571934620/ by http://www.flickr.com/people/mathizarthegreat/, on Flickr

I also needed to modify one of the fittings to have a barb on it for the fuel line, here are pictures of me chucking it into the lathe and turning it down into the needed barb shape:
http://www.flickr.com/photos/mathizarthegreat/8571934502/http://www.flickr.com/photos/mathizarthegreat/8571934502/ by http://www.flickr.com/people/mathizarthegreat/, on Flickr
http://www.flickr.com/photos/mathizarthegreat/8570840297/http://www.flickr.com/photos/mathizarthegreat/8570840297/ by http://www.flickr.com/people/mathizarthegreat/, on Flickr
http://www.flickr.com/photos/mathizarthegreat/8571934386/http://www.flickr.com/photos/mathizarthegreat/8571934386/ by http://www.flickr.com/people/mathizarthegreat/, on Flickr

Once all the polishing and machining was done, I cleaned the bottle of all grease, cutting oil, and buffing compound:
http://www.flickr.com/photos/mathizarthegreat/8571934548/http://www.flickr.com/photos/mathizarthegreat/8571934548/ by http://www.flickr.com/people/mathizarthegreat/, on Flickr

I then assembled the bottle, yielding this finished component, the haze you see on the bottle is an artifact of the camera and grease from my hands. When assembling I used Honda Bond on the threads of the A/N fitting to insure a good seal. Unlike pipe fittings that seal on the threads, A/N fittings rely on compression of a barb inside the fitting, because I only had threads to use when attaching them to the bottle, I required a sealant of some sort:
http://www.flickr.com/photos/mathizarthegreat/8571934362/http://www.flickr.com/photos/mathizarthegreat/8571934362/ by http://www.flickr.com/people/mathizarthegreat/, on Flickr

I am pretty happy with the way this turned out. I will be installing it soon, I will be sure to provide before and after pics of the look of the tank in my engine bay.

Thanks,
Matt

 

Nicely done...

 

Good job. I definitely wouldn't call this a DIY. A custom one off, yes. I know I don't have access to any of the tools you did to replicate this.

But anyway. Though up a mounting system for it?

 

Looks good

 

Nice write up

 

I like it, thanx for the write up

 

That looks pretty nice. I've seen others build something similar to this, but yours is definitely the cleanest.

 

Pretty innovative, good work

 

Nice. I like how you polished the tank. It looks clean.

 

it looks like you put a "plug" in the top and sealed the tank up? if so, its not gonna work...... the overflow tank has to be vented to allow the coolant to expand into the tank as it heats and suck back up as it cools. if the tank is not vented, it will create pressure/vaccum and not work properly.

 

Really? Interesting, the OEM tank did not have any obvious vents. I was under the assumption that the coolant would just create a pressure in the bottle as it was pushed in and out. I'll have to look into adding a vent, should be easy enough.

Also, here are some pictures of it installed:

http://www.flickr.com/photos/mathizarthegreat/8588048364/http://www.flickr.com/photos/mathizarthegreat/8588048364/ by http://www.flickr.com/people/mathizarthegreat/, on Flickr

http://www.flickr.com/photos/mathizarthegreat/8588048156/http://www.flickr.com/photos/mathizarthegreat/8588048156/ by http://www.flickr.com/people/mathizarthegreat/, on Flickr