Introduction: Computer Liquid Cooling With Car Parts!

This Instructable will document how to build an external liquid cooling system for a computer based around an automotive heater core. This Instructable is really more of a guide than a set of instructions to create a duplicate system. Make yours as flashy or utilitarian as you desire.

Step 1: Gather Materials and Plan!

First, a short disclaimer. I am not responsible for any damage you do to yourself, others, or your computer or other property if you choose to attempt this project. If you are unsure about building your own system there are plenty of kits and all-in-one closed loop coolers out there that may be more suited to you. If you have some level of DIY experience, are comfortable with taking the life of your computer into your own hands, and want a liquid cooling system that stands out, this is the project for you.

To build a liquid cooling system you will need:

*A radiator of some sort. I used a heater core. specifically, one meant for a 1977 Bonneville with A/C. You can use pretty much any other type of radiator or heater core, but my recomendation is to stay away from the aluminum ones. copper or brass only is the way to go. having mixed metals in the loop can cause galvanic corrosion. the purpose built radiators commonly available at stores like frozencpu or xoxide are great too but expensive. heater cores are able to work as well or better and only cost 25 dollars or so. 

* A pump. I used the danger den 800L/hr model.  other pumps will work but keepin mind flow rates and noise. This pump pushes a lot of water almost silently, so its worth the money that I paid for it.

* wood. I used 1/2" birch plywood. this is great if you are going to stain or paint it black like I did, but solid wood would also be nice. 

*fans. I used 4 cooler master r4 120mm fans. they probably are not near the 90cfm they are rated for, but they still push a good amount of air, and are relatively quiet. I used 4 so pricey fans will definitely add up. these are available for about 7 bucks each if you shop wisely. 120mm fans push the best air vs noise ratio, plus they are ideally suited for the size of my heater core. 

* A reservoir. Mine is made out of a piece of clear PVC. Use your imagination, I am sure there are lots of other things that could be used as a reservoir, I just can't justify spending 40 bucks on a plastic container.

*hose barbs, vinyl tubing. I used 3/8" ID tubing, but half inch works well too and increases flow rate.

*assorted screws, bolts, scrap aluminum pieces, switches, connectors, leds, etc. you can personalize your system any way you like. I will probably be adding some UV leds to make the coolant reservoir glow, but the sky is the limit here.  

Once you have gathered your Materials, its time to plan out the dimensions and structure of your enclosure. I decided four fans in a Push/pull configuration would afford the maximum airflow through my radiator. a separator divides the box into the "wind tunnel" section and the pump/ power section. a slight groove in the box retains the radiator. If you decide on only two fans, they seem to be more effective at pulling air through the radiator than pushing it. perhaps placing the radiator near a large vent and four fans pulling air through the radiator and out of the box would be more effective, or two smaller radiators mounted in the ends of the box with four fans exhausting air out of the box. The advantage of my setup is I can selectively turn off a pair of my fans. Once all of the details have been ironed out, begin cutting the wood according to your plans. 

Step 2: Test Fit

 Do this many, many times to ensure that things are going to fit into the enclosure as planned. notice how things are situated and consider how you will run the tubing at the end. I didnt really leave much room for tubing in my design, only an inch between the fans and the radiator, so finding small enough fittings was a challenge. I have my loop set up so that the pump pushes water straight out the the computer, then returning water travels through the radiator before being deposited in the reservoir. the pump draws from the other end of the reservoir, where the bubbles have largely settled out, and continues the cycle. determine which way the hose barbs on your radiator should point.

Step 3: Solder Up the Heater Core

 once you have determined the appropriate direction, connect elbows and hose barbs appropriately. test fit as necessary to ensure proper fitment. once you are satisfied with it, disassemble it and clean all surfaces of the copper and brass parts. fill the radiator up to the brim with cold water, to help prevent it from desoldering and causing leaks. wrap everything but the upper tanks in a soaking wet towel.  apply flux liberally to all parts and twist together. carefully solder the pipe fittings together taking care to only heat the fitting you are working on. the tanks on top are only held on with solder,and are difficult to put back on if you have accidentally unsoldered them.  allow to cool when you are satisfied with it.

To test for leaks, put a short length of tubing onto one barb, then fold it over and clamp it. then attach a second longer tube to the other side. submerge it in a bucket of water, and either blow into the tube or use low pressure from an air compressor. watch for bubbles rising from any leaks. redo soldering job if necessary to fix leaks.

Step 4: Build Power Connector and Switch Panel

 You may wish to build a nice panel to hold any switches for lights, fan control switches, power connectors etc. This makes it easier to install switches and things as 1/2" ply is too thick to mount these things in. I wired my switches such that the top two turn each side on or off completely, and the bottom two switch between the full 12 volts and 7volts. at 7v the fans are nearly silent, but still push adequate air. At 12v they are still to very loud, but push much much more air through the radiator. I have done this in the same way as the so called "7 volt mod" that is discussed elsewhere on the internet. when the switch is in normal mode the + wire of the fan gets 12v and the - side gets ground or 0v. in the 7v position, the + side still gets 12v but the - side gets 5v, for a voltage difference of 7 volts. The power connector is just one I found at the local electronics place, and connects to a 4-pin molex connector on the computer it is cooling. it carries the 12 volt, 5 volt, and ground rails from the power supply to the external box.

Step 5: Glue Time

 Once satisfied with the layout of the box and all the appropriate holes for mounting and tubing are drilled, you can glue the whole thing together permanently. Unfortunately, I forgot to take pictures of this because you kind of have to work quickly but carefully. Use lots of clamps, and wipe up the glue squeeze-out with a damp towel to avoid staining the outside of your box. I also did not take pictures of the staining and finishing portion of the project, but any type of paint, stain or varnish should be adequate. I used two coats of black stain followed my three light coats of polyurethane, sanding lightly between coats. black spray paint would have worked, as well as latex paints or other varnishes.

Step 6: Final Assembly and Testing

 When your paint is dry its time to put everything back together for good. your project should be coming together! once your tubing has been run, and hose clamps applied its time for the first test. I connected the loop that would normally go to the computer together to test the system out. say a little prayer and begin adding coolant to the reservoir. If you have constructed your system well, it wont leak! as always, exercise extreme caution when mixing water and electricity. yes, the atx supply is only 12v but the cord its plugged into isn't. sucking some water through the pump to prime it may be necessary, mine did it just by gravity. do not allow the pump to run too long without water in it or it will overheat. green food coloring is optional but recommended.let it run for a good long time to be sure that there are no leaks in your system.

when you go actually attaching this to a computer, be sure to use distilled water and anti-corrosion coolant to be on the safe side. coolant comes in a multitude of colors and is generally UV reactive, so installing black lights on your box isn't a bad idea. Congratulations, You now have your very own liquid cooling system!

My project here is not quite done yet, I am 90% there but a few details still need to be finished. I will probably make some fan grilles for it, possibly made from expanded steel for that industrial look.  I do not yet have my water blocks to cool with this, and it may be some time as my daily driver recently broke down and my project money has been diverted to pay for repairs... I will update with my results when I am able to actually run it, and when I add any extra things to it.

Step 7: Install!

 prior to installing the water block on your computer, you should do a leak test to ensure coolant isn't going to spray out onto your motherboard or something.  Cut your tubing to the appropriate lengths, run them through the opening in your case, and make sure the hold-down plate and hose clamps are already threaded onto the hoses before you connect the block. This will make it easy to install once we are sure it doesn't leak, and wont require you to drain the loop after we test it in order to install it. fill the reservoir and start the pump. some gentle shaking may be required to prime the pump. if water doesn't flow through immediately do not allow the pump to run for too long without water in it, or it will overheat and break.  leak test the block for as long as you can impatiently wait :)
The next step, assuming you block(s) don't leak is to actually install them. this is a different process for each socket type, I am using a lga775/1366 style mount, so it is necessary to insert the backplate on the rear of the motherboard. once that is done, apply thermal compound, and slide the block and hold down plate over the posts attached to the back plate. get each nut started on the four posts. tighten until they are pretty snug, but do not overtighten or you will crack your motherboard or break the CPU Die. connect your power cable to the external box and fire up the computer! 

With my CPU currently The only thing in the loop, I am seeing idle temperatures of 25 to 32 degrees Celsius, and under 100% load in prime95 45 to 52 degrees, depending on the ambient air temperature. This is a huge drop from ~60 degree idle and 85 degrees under load I was seeing with the stock cooler that came with the boxed processor.  These readings are all with stock cpu frequency and using the Enzotech Sapphire scw rev.A block.

I think the next step for this project is some type of temperature monitoring system to measure air temp and incoming and outgoing coolant, as well as expanded cooling of other motherboard components and graphics cards.