My Rendition of a Car Radiator PC Loop!

[LLCooLM495]

I know I'm definitely not the first person to run a setup like this, but I figured I'd share anyways, since most of the threads I found on this kinda thing from other forums were a little lacking in detail, and I had to go through a bit of trial and error with the adapters.  Since I got into watercooling about 5 years ago, I'd always wanted to try hooking up a car rad to a loop, since working on cars is my biggest hobby apart from PC stuff.  After watching the disaster that was LTT's car rad video a few times, I figured I'd finally give it a shot, since my parents aren't here in my dorm to stop me from bringing car parts inside  Ended up with an original 1970 Camaro 3 core radiator, which uses a full copper core with brass end tanks; $50 from Facebook marketplace!  Some new tubing, $20 worth of PVC schedule 40 adapters, a $25 Harbor Freight pond pump (264GPH, 5.5ft head pressure; submersible, comes with a 1/2in barb adapter for the outlet, and has a removable/ washable filter for the inlet), and a few gallons of distilled water/ Primochill's included additive later, here it is!  Got it propped up next to my window with a box fan blowing cold air from outside through into the room. 

 

 

ADAPTERS

For the adapters, on this specific rad, I ended up using a rubber 1-1/4in to 1-1/2in adapter on the inlet and outlet.  The outlet measures 1-1/2in, but the adapters turned out to be a bit oversized, so had to try a few before I got ones that fit snugly.  From there, used 1-1/2in Schedule 40 PVC to 1/2in NPT threaded adapters, then put 1/2in x 1/2in MNPT barbs into those using T Plus 2 PTFE pipe sealant on the threads.  From my research, found that it's best practice to use a non-setting thread sealer for this kind of connection, as opposed to the usual PVC cement.  The sealant is rated for potable water systems as well, so I felt alright about having it in the loop, and it doesn't appear to have mixed with the coolant anyways, so I'd say it's working properly.  The first time I tried to get this loop done, I used brass barbs in the adapters, but as it turns out, brass won't seal properly in PVC threads, so keep that in mind if you try this. 

 

RADIATOR CAP

Finally, I ended up getting one of the pressure release style radiator caps, which actually turned out to be a huge help.  The spring in the cap seals the neck of the rad, but if you lift the lever, it'll bleed all the air out of the loop through the overflow tank stem; very handy feature, and the cap was only $8 on Amazon.  Keeps the system sealed with the lever down as well, so I didn't have to plug the overflow tank stem like I thought I would.  A regular style cap would be a PITA to bleed, since it won't open unless your coolant pressure gets above 15psi, which isn't going to happen in a PC loop, so I'd recommend getting this kind of cap if you wanna build one of these rigs.  

 

TUBING/ COOLANT

I used 7/16in ID x 5/8in OD Primochill Advanced LRT tubing, which fits snugly over the 1/2in barbs (may have to stretch it and fiddle around to get em started though), and just used standard PC G 1/4 compression fittings for the PC side of the loop.  The Primochill tubing also comes with an additive that makes a gallon of coolant with growth and corrosion inhibitors, which I've been running with no issues in my regular loop for 5 years now, so I trust that it'll keep the loop clean (enough).  Took somewhere around 4 gallons to fill the loop, including the 2 gallon bucket the pump is sitting in; the other 3 gallons are just plain distilled water, but when I move out of my dorm, I'll probably spend the extra money for more of the Primochill additive just to be safe.  It's about $13/ gallon, which is actually cheaper than antifreeze where I am!  Speaking of, I do have antifreeze on hand for when the temps start tanking here in Virginia as we get closer to winter, so we'll see if that ends up being necessary.  Could always just close the window, but I'm a sucker for low temps on my components, so I'll keep it open unless I start seeing condensation.  

 

Oh, and back on the topic of the Primochill tubing, I'd also like to note that they say the tubing IS compatible with antifreeze, so that I shouldn't have to worry about adding it if/ when the time comes.  JayzTwoCents did a couple videos a few years back with antifreeze in a loop, and it worked perfectly fine for a few months; only replaced it in his follow up vid because his DDC pump got shorted on the heatsink and he had to drain the loop.  Antifreeze (at least the regular green kind, do some research on the different kinds to know the difference; If I recall correctly, the red Toyota coolant is only used in full aluminum systems, and I haven't looked into the orange or yellow types, but they all have different additives for the systems they were designed for; green was made for older cars with iron block engines, copper or rads, aluminum heads, copper heater cores, etc.  Lots of different metals, so do your due diligence if you wanna try this to make sure you use a coolant that'll be compatible with your specific rad/ blocks)... er, got a bit rambly there, so I'll digress  Anyways, antifreeze is designed to be in systems which use rubber, so you shouldn't have to worry about the seals in your loop degrading.  ANYWAYS, that was all a lengthy roundabout way of saying that the Primochill tubing will work with antifreeze, and I'd imagine other soft tubings for PC cooling will as well, but just make sure that your tubing of choice is compatible if you want antifreeze.  I believe most hardline tubing won't work, specifically PETG.  I also wouldn't recommend doing hardline for this kind of thing unless you're quite certain that you're gonna keep the radiator and PC exactly where they are.  Always preferred soft tubing for ease of maintenance personally, since I'm more concerned with performance than looks.  Bet you could make a setup like this look pretty slick with copper tubing though; industrial chic! 

 

TL;DR:  Make sure you do your research on coolant compatibility!!  And don't do what Linus did in whole room watercooling, since antifreeze doesn't contain growth inhibitors!  (car cooling systems don't need growth inhibitors since the heat from the engine will kill anything in the loop.  Your PC will NOT get the coolant into the 220f+ range like an engine will)

 

PERFORMANCE/ RESULTS

Only have it hooked up to the GPU block for now, but it's been working for a bit over a week now with no issues.  Really wish they'd properly hooked up the rad in the video, because it really does work quite well, and the adapters were only about $20 total.  Even better though, if you poke around on secondhand marketplaces, you can find a good amount of full copper rads from older cars for quite cheap, since a lot of people with those cars like to move up to new 4 core aluminum rads and the like.  All in, I paid about $135 for the full setup, not counting the GPU block.  Hope they revisit this concept on LTT and actually do it right.

 

As for performance, obviously it's quite good.  Pump actually has pretty good flow through the whole loop, and the GPU idles at about the temps of the weather, maybe 1c higher.  Got down to 12c at idle the other night when it was in the low 50f range, and running Cyberpunk with the 1080ti overclocked to 2075mhz/ 6107mhz mem, it peaked at 23c, and managed to stay at 2075mhz the entire time!  When it was hooked into the CPU loop (780mm total rad area, sharing the loop with an i7 6950x @ 4.2GHz/ 1.24v), it would sit closer to 34c in the same conditions with the windows opened, and clocked down closer to 2012mhz.  Really no actual impact on performance, but hey, its nice to see the clocks staying up.  Got it to keep a stable 2113mhz in Time Spy as well, hoping to see it go higher once winter kicks in.  

 

CHANGES I'D LIKE TO MAKE

Eventually, I do want to move to a traditional style D5 pump with a reservoir, but I went with the bucket/ Harbor Freight pump for now because budget.  At the very least, I'd like to drill some holes in the lid of the bucket so the tubing can pass through and I can keep the bucket sealed.  Would also like an actual way to mount the rad in one place as well, since it's just leaning against the window frame, but its been stable on the shelf, so it'll do.  One last thing I considered trying, and may end up doing eventually, is to get some brass caps in the size of the inlet/ outlet for the rad, then drill/ tap them for G 1/4 thread, and braze them to the radiator.  If that's done properly, it should theoretically hook up to a PC the same as any standard PC radiator, but I'm using the adapters for now since I don't have access to any of the tools for that here in my dorm room.  Plus, that adds a bit of cost, and it means you'd be permanently modifying the radiator, so it'd never really work in a car again.  Probably not a concern for most people, but I would like to own a 2nd gen f-body one day, so I may end up putting the rad back into the car it was designed for.  Probably not, but you never know!  Would definitely make the setup a bit more "proper" though, assuming it was done right.  

 

I'm also not sure if I'm going to make use of the transmission cooler lines.  The lines lead into a cylindrical reservoir inside of the passenger side end tank, and it's designed to actually heat the trans fluid and keep it at operating temp.  I'm sure if you wanted to get wacky and wild, you could do some kinda system with a condenser or a chiller through the trans loop, but it'd be pointless to add it into the loop with the main rad, since the coolant would be at the same temps.  

 

I'M FINALLY (almost) DONE TALKING!

Apologies for the long post, but hopefully I remembered to put in all the little details for how to actually set the loop up, in case anyone was looking into doing something similar.  If anyone has any questions or wants some clarification on anything I may have accidentally left out, let me know!  Would love to hear back on any advice some of y'all may have on this kinda setup as well, since I'm new to the whole janky watercooling world; this whole project is just me experimenting, and I'm definitely no expert.  

[heimdali]

What happened to the fan that's supposed to move air through the radiator when in the car?  You shouldn't miss out on it   And what are the 1/4 mile times?

[LLCooLM495]

4 minutes ago, heimdali said:

What happened to the fan that's supposed to move air through the radiator when in the car?  You shouldn't miss out on it   And what are the 1/4 mile times?

Unfortunately the guy I got it from didn't have the original fan or shroud, the rad had been sitting in his garage for about 25 years apparently, sold both of his Camaros awhile ago.  Has a pretty sweet '67 GTO now though! 

As for times, I'd say it runs a modest mid 11 second 1/4 mile in the right weather 

[heimdali]

Awww, so the engine that fan was attached too is gone, too ...  but 11 is good

 

[LLCooLM495]

11 hours ago, heimdali said:

Awww, so the engine that fan was attached too is gone, too ...  but 11 is good

 

Gone from the original owner, but I'd bet the motor is still out there somewhere.  Hard to kill a SBC! 

[heimdali]

Reliability is good for things like that.

[Tiderfish]

Great setup. I have always wanted to do this. More so I could dump the heat outside of my office and cool the PC at the same time. 

 

As for the car's fan, most older cars used belt driven fans, so they wouldn't work for this, however you could go to a junk yard and find a small AC fan that sits on the front of the condenser/ radiator stack and blows into the engine bay. But be warned. Most modern electric radiator fans are mega powerful. Like 60 amps @ 12VDC powerful. The manufacture uses a PCM unit to control the voltage in so they can modulate output depending on load. 

I learned all this the hard way when trying to do swap a belt driven fan to a e-fan on my truck without a PCM to modulate it. Basically it would run full chooch once the water got hot, and destroyed my battery. I could have fussed with it more, but in the end the goal was reliability, and the belt fan is reliable.

 

 

[Aragorn-]

I'm not sure you'd want some massive 1200cfm automotive fan blasting away anyway... Clearly an alternative solution is required.

 

How does it run without any fan? just passive cooling...

 

dont you have the pipes backwards on the rad? Cold water out the bottom, into the pump, then off to the CPU... then Hot water returning to the top of the rad?

[Bestscrewdriverever]

I did sort of the same thing with an alphacool 560mm rad and some industrial noctua fans. An extra 12" of tubing and a couple of small holes in the wall and viola! I made an enclosure and painted it the same color as my house. The outside fans are linked to the coolant temp sensor. I can make a fan curve to manipulate coolant temp

 

 

 

 

 

[LLCooLM495]

On 1/12/2023 at 11:17 AM, Aragorn- said:

I'm not sure you'd want some massive 1200cfm automotive fan blasting away anyway... Clearly an alternative solution is required.

 

How does it run without any fan? just passive cooling...

 

dont you have the pipes backwards on the rad? Cold water out the bottom, into the pump, then off to the CPU... then Hot water returning to the top of the rad?

Apologies for such a late response, been caught up with my last semester of college.  Totally agree that an actual electric radiator fan from a car would be a bit much for something that sits in the room with you.  

 

As for passive cooling, it does pretty well for the most part, but I do notice temps creep up when gaming without the fan on.  Saw it get up to around 60c awhile back playing Sniper Elite v3, which isn't bad by any means, but was a bit hot for keeping the overclock on the 1080ti stable.  Pascal cards can get a little finnicky with temperatures when overclocking (I was running the card somewhere around 2112mhz for gaming, got it up to 2240mhz awhile back doing some GPUPi benching: https://hwbot.org/submission/5126530_tomoko_gpupi_v3.3___32b_geforce_gtx_1080_ti_8min_8sec_286ms).  Totally fine on stock clocks, though.  

 

For piping, I have it set so the pump sends water into the top of the rad, then goes to the GPU from the bottom, and finally comes out of the GPU into the reservoir with the pump.  Order isn't super important in PC loops, as Jayz2Cents showed awhile back, but with this setup, I have the coolest water getting sent directly to the GPU.  The water in the reservoir hasn't gotten nearly hot enough to pose an issue to the pump, so I reckon this set up is pretty much ideal for what I'm working with.

 

With all that being said though, I am happy to report that the setup is still running strong.  Unfortunately, with winter gone, I'm not able to bank on low outside temps, but it is still performing well with the window closed.  I'll likely have to find a new solution for everyday use after I move out of my dorm since my dad isn't too keen on me keeping a car radiator in my room, but I figure I'll be pulling it out into the garage when winter comes around to do some more high-clock benchmarking  

Even with winter being over, I have enjoyed having separate loops for the CPU and GPU, so I may end up building an enclosure for extra rads and an extra pump to sit under my tower, pretty much like the basement from a 900D or a CaseLabs SMA8.  Overall though, I would call this little project successful, and its been a ton of fun, even with using it on "older" hardware.  I believe that I still hold the record on HWBot for an ambient watercooled 1080ti in GPUPi v3.3 32B (link to the run is a few paragraphs up), scoring above some chilled setups, and getting pretty dang close to a card that was hooked up to a phase change system.  Very reliant on weather, of course, but definitely shows that the radiator is doing its job!