Water cooling loop flow issue
Water cooling loop flow issue
Hey everyone,
I'm facing a problem with my hardline cooling loop. Water flow beyond the CPU block isn't happening. This video might help clarify the situation:
https://youtu.be/NHdNbfgqeOM
TLDW: My setup is pump/res to GPU block (2) to Rad, then CPU block, then back to RES. Coolant flows through the entire loop but only trickles past the CPU block, and no flow reaches it. I've tried moving the case in all directions and changing the pump speed, but nothing seems to improve the situation. I've had this setup before successfully, so I'm trying to figure out which part of the loop is causing the issue. Recently, I drained the loop and bent one of the tubes during yearly maintenance.
Hello,
It seems the water might be trapped somewhere due to vacuum pressure inside. Since the liquid didn't flow into the reservoir, the bulb appears stuck, so you probably didn't open the cap to release air. Have you verified that all fittings are secure and not leaking? (just for your reference)
Hey Robert,
I removed the cap from the reservoir and turned the case upside down without it. I accidentally spilled some coolant from the top. After that, I took out every piece of tubing and reinserted them to make sure all connections remain tight. Any other advice?
It seems like a mix of restriction and airlock issue. If coolant isn’t returning properly, could the port be blocked? Also, can you increase the reservoir fill more easily? Your radiator probably has air in it, and the tubing near your CPU block suggests the pump struggles with air pockets. Air is compressible, which is why it stays, while liquid doesn’t. You’d need a way to let the coolant push the gas bubbles out—running the pump with the reservoir vented might help.
Are you considering using one radiator for SLI + CPU? What methods can improve liquid flow through the loop? Changing the radiator ports—specifically placing the case on the side with lower inlet than outlet—might help. Connecting GPUs in parallel could also be beneficial.
It seems like a mix of restriction and airlock issue. If coolant isn't returning properly, could the port be blocked? Also, can you increase the reservoir fill more easily? Your radiator probably has air in it, and the tubing near your CPU block suggests the pump can't push coolant through the air gap. Air is compressible, which is why it stays liquid, but gas bubbles need to move. You might need a way to let the gas escape so coolant can displace it—running the pump with the reservoir vented could help.
Hi Rubix.
I'm trying to operate the pump with the top of the reservoir open, but it's been running for hours without progress. I believe your air pocket theory is correct. I plan to drain the loop tomorrow and remove the 90-degree fitting at the end of the loop, as that might be restricting flow.
Are you thinking about using a single radiator for SLI + CPU? What would actually improve liquid flow is changing the radiator ports—specifically, having the inlet lower than the outlet when the case is on the side. It would also help to connect the GPUs in parallel. Thanks for the advice; I’ll try this next time I build something like this. These concerns are real, but they don’t seem to be the main cause right now.
Reconnecting tubes offers minimal effort to ease the flow restriction (parallel GPU). For the rad, a large size would require it to be at least 480mm long and over 40mm thick, with fans on both sides.
When you turn on the pump, do you keep the cap open? You should leave it vented when filling the loop so that coolant can move freely. Otherwise, there’s no place for it and it might try to compress, stopping the coolant flow.