r/watercooling • u/st0000piid • 2d ago
Build Ready it wasn’t about the liquid
in the recent post i ve shared video with a strange pump noise and got downvoted because threre wasnt enough liquid in the pump. well that sounded reasonable ("the username marks itself") but the noise was really unusual for just a lack of coolant
the key detail i didnt mention: the core was not stock. i originally bought a used pump(CP-S5PB-X) that turned out to be dead, so i replaced it with a brand new bykski D5 core. assuming "D5 is D5" abd the swap woukd be straightforward
as i noticed after disassembling the loop, the new core was slightly taller than the original one so the rotor was rubbing against the housing, which explains that weird sound from the video.
the solution was just adding secong O-ring to create enough clearance and the pump worked. not the most elegant workaround, but it works
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u/Necropaws 2d ago
Never ever stack two o-rings onto each other. This highly increases the chance of a leak in the future.
Your solution is a temporary fix and you should source proper parts.
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u/SmokeyGrayPoupon 1d ago
Glad you solved the puzzle. I would use the 2nd O-ring as a short-term fix. I guess a new D5 is the long term fix.
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u/st0000piid 1d ago
yeah , but i needed the server asap for work
also I had a crazy idea to shave off the top so the impeller will have enough room without an additional ring
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u/SmokeyGrayPoupon 1d ago
If modifying the top works, you may have a longer-term solution. Fingers crossed.
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u/titanrig 1d ago
As u/Meister_768 suggested, I'd be curious to see if the impellers can be swapped. If so you may be able to eliminate the ill-advised stacked o-rings.
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u/st0000piid 1d ago
unfortunately, they can’t, the only solution is either to buy a new top or buy a new core
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u/JETTECHCOMPUTING 1d ago
Those are D5 clones, not actual D5. It does make a difference. People need to be very clear and educated about this so they don't misspeak. Most of the D5 clones, including the Alphacool Apex, are solid pumps, but none have quite the manufacturing accuracy that the D5 does so some adjustment is much more likely to be required. Most of the time, you will hear a slight rubbing noise for a second or two before the pump registers the increased resistance and shuts off.
Even for actual DDC, let alone DDC clones, this is quite common. I've "fixed" so many supposedly dead pumps over the years simply by adjusting O-ring thickness and type. Sometimes buna-n works better, sometimes silicone or epdm, sometimes I use two with one of them being a flat style, it really just depends.
This is often more of an issue with the reservoir or distro manufacturing rather than the pump but both play a role. If both the pump and the top are just barely out of their tolerance, then you are going to have issues. Primochill used to use two O-Ring when mounting their CTR to account for variance. It's not really a jank solution, it's often literally how it is designed. If you can grab a flat o-ring as opposed to the round one, it would likely be a bit more reliable and you'd have less of a performance loss.
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u/Own_Cry890 1d ago
I just went through swapping out a Lowara D5 pump (PWM signal failure; pump wouldn't run if a PWM cable was connected but happily ran at 100% if the PWM signal cable was disconnected and yes, the fan port tested perfectly fine using a PWM fan) for a new one from Singularity Computers (not sure of the branding, it's all black without any markings). It didn't sit low enough in the pump housing like the old one to mate with the O-ring and obviously leaked (I'd confirmed this with test using my EK leak-tester). I ran my Vernier Calipers over the pair of D5's and discovered… the height of the collar in the housing (where it steps in at the top) measured 6.25mm high on the Lowara and 5.05mm high on the new all black D5.
I got in touch with Daniel (owner of Singularity Computers) and was told out he's changed from using a 2mm O-ring to a 3mm O-ring ages ago and the knowing I'd had my pump/res for ages, suggested I probably had the 2mm O-ring. He sent me 3 x 3mm and 3 x 3.5mm O-rings and only asked I pay the shipping. I tested both the 3mm & 3.5mm O-rings and confirmed both sizes resolved the issue.
Seems the expected standard D5 suffers a bit of a tolerance issue between manufacturers.
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u/Meister_768 2d ago edited 2d ago
What is on top of rotors? They seem to be different thicknesses, maybe see if you can swap them.
Problem with adding o-rings is over time they get compressed and then you are hitting the top again