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.

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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. 

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    79 Discussions

    Hello, i really like this refrigeration system and i wont to build one, but first i have to ask you, what do you use as a power supply, a normal pc power supply?


    4 years ago on Introduction

    I think I would use some antifreeze that is safe for pets in any of the CPU cooling kits instead of dye and that way if it does leak your pets are OK. You might also use a piece of anode rod material from an old water heater in the water to stop corrosion. Clean and sand it so the material surface is better exposed. If there are any chemists out there that know if this might not be a good idea please comment. I know some of the hot water heaters suggest that anode rods can be too active or deactivate over time but I would think this would be mostly on the outside of the anode rod. And they are FREE on thrown out water heaters or at the salvage yard. Also a small piece of silver to stop bacteria I've heard helps.

    Nice build.


    5 years ago

    I hope in the future you intend to cool your hole pc with this system because that is a bit overkill for just the cpu


    5 years ago

    could you explain me how you had connected the cooling system with your CPU ?


    6 years ago

    The reservoir reminds me of the things the Green Goblin had in the Spider-Man movies. lol


    7 years ago on Introduction

    actually on the galvanic corrosion thing its easy to stop usually just place a piece of solid zinc rod in the system somewhere with coolant flowing over it.

    it makes a sacrificial anode and eats the zinc instead of anything important that and one of those water additives like reline, royal purple work awesome on cars and bikes so i see no issue it could cause with pc's myself

    aside from that you could also swap the heater core for a Oil cooler available from summit jegs or other sources for maybe about 30-40$(or scour some junkyards, or e-bay ) and also get a slimmer package with many sizes available up-to something like 10-12"X 20-24" they also come with usually 3/8
    i would probably take off the fittings for the inlet side off offering full 1/2 flow and 3/8 outlet.

    i would use one like above, i would use a multi pass tube fin type as opposed to the wide open ones that have 1 pass with many rows.connected parallel

    tubing To make it easier to interface with pumps and hardware
    honestly probably build one with all 1/2 tube with the radiator being the only restriction given the choice.

    1 reply

    Reply 7 years ago on Introduction

    i think you might also want to use some rubber/plastic firewall grommets to prevent tubing tubing from getting rubbed through, worn or cut by the sheet metal


    8 years ago on Step 7

    What are your parts(The aesthetic ones-Case, PSU, other things that light up)? I really like the way they look, and would like to implement some of them into my build.

    4 replies

    Reply 8 years ago on Step 7

    The Case is a Thermaltake Element S which is a pretty great case for the money even if its not too flashy. The fans on the radiator box are cooler master R4 which I chose mainly for the price. They also come in red and blue but are a little bright if you are going to put the setup in a room which you also sleep in. I had originally planned to go for red fans and coolant to match the red and black theme of the case but they were out of stock at the time. I'm also considering upgrading them to PWM 4-pin fans that can be smoothly controlled instead of just low -hi-off like these. The psu pictured here is a OCZ gamexstream which I actually don't recommend because the first one was DOA and its replacement failed within three months. OCZ does have great customer support though and replaced it with an upgrade to a Z-series supply. the waterblock is an Enzotech sapphire block which performed well in reviews and was much cheaper than the competition. I've been very happy with my setup thus far, its probably past time for a system drain and cleaning so i'll probably update this instructable with how its held up after I've done that.


    Reply 8 years ago on Introduction

    Do you happen to know if anti-freeze damages acrylic? I'm making a DIY water cooler right now and made an acrylic reservoir (IMO I made it about 4X the size i needed) but i don't know if anti freeze will damage it as alcohol and a few other substances can damage and crack it.


    Reply 8 years ago on Introduction

    not really. I have a swiftech kit liquid cooling system and thier res. is acrylic. Had it since 2006. Used 50/50 (highlighter yellow) car coolant. The res. is in perfect condition still.


    Reply 8 years ago on Introduction

    Also, im getting a 120mm radiator made for watercooling, its a DD black ice xtreme to be specific, but I've been wondering if it would work worse or better than a heater core.


    8 years ago on Introduction

    OMG i have those same speakers on my PC desk, perma-hooked to my 32"hdtv/monitor. BOSE rocks.


    9 years ago on Introduction

    I've read a few of your guys comments on here ... one in particular asks about why not antifreeze??? then others stated it wont be any good.....And you should use water.... Well why not antifreeze???? I think antifreeze used diluted down to where its really not useful for automotive use would be perfect...  then you don't have to worry about stale water... or bacteria growing as one person put it... THEN what about just using oil?????  like a synthetic brand  or my favorite tranny oil.... (a complicated mineral oil) One thing I'm sure that  is taken into account but not mentioned in the instructable  is room for expansion of what ever liquid you use or is that an issue???

    2 replies

    Reply 9 years ago on Introduction

     I actually in the end did use a dilute solution of antifreeze in the loop in the last pictures. distilled water, a bit of antifreeze and a little UV dye. I don't know if its really helping or hurting my performance, but it should at least keep the bacteria from growing inside the loop.  
    Water is superior to oil for liquid cooling loops because water is both a better heat conductor and has a substantially higher specific heat.  water is 4.19 Kj/Kg*k while most oils are only about 1.8 Kj/Kg*K. This means that it takes more than twice the energy to raise a mass of water one degree as it does to raise the same mass of oil one degree. This is good in a liquid cooling system because the water can transfer more heat at once, and will not approach its maximum heat carrying capacity quickly even if you run it through several water blocks.  interestingly, both propylene glycol and ethylene glycol (components of antifreeze) have a substantially lower specific heat than water as well, around 2.5 Kj/Kg*K, but I don't think its hurt my system any.
    As for expansion of the liquid, I never really thought about it when I was building it, but now I'm thinking I probably should have because when I turned off the fans to see how quickly the coolant would heat up I saw that once it was pretty warm there was about a drop of coolant that had leaked out of the threads where the barbs screw into the reservoir... I guess I need to tighten them and leave a small bubble of air in the reservoir for some expansion room. 


    Reply 8 years ago on Introduction

    Okay, first off: Yes, I know this is a year after, but I just want to say it anyways.

    Oil would in fact, based on your numbers, be better for cooling. Think about it, it takes 2x as much energy to raise xL of water 1F than oil, meaning that water's an INSULATOR. The same concept can be said about metal heat sinks; it takes much more energy to raise the temperature of steel compared to aluminum, aluminum's a conductor, you want it to PULL heat away from your processor :)