Hello everyone. New to the forum and I'm in need of assistance with my closed loop. I recently pulled my hardware out of my Case Labs SM 8, Hardware Labs Black Ice Nemesis GTX 480 and 240, running a DDC pump. 2x GTX 1080 it's and a I7-8086K.

I put all my hardware onto my test bench so I can start modifications to my SM 8. First using my HWL GTX 480, I put the loop together with 3/4-1/2 soft tube and a new D5 pump reservoir combo from Singularity Computers. Started to fill the loop with Myhems system prep 2 and turned the PSU on to prime. Pump starts but I have absolutely no pressure.

Knowing the loop would prime with my DDC pump, I drained everything and installed my DDC pump reservoir combo, Singularity Computers again, filled the loop and the same problem occurred.

I decided to drain the system again and replace my HWL GTX 480 with a EK PE 360 I had in storage. Filled loop and again, no pressure with the D5 pump.

I have less than 3 feet of tubing ran and no kinks in any of the tubing. DDC and D5 pumps are running 100%. Loop order is Pump out to CPU in, CPU out to GPU in, GPU out to radiator, radiator to top of reservoir. Only running one GPU on my Test Bench.

It's a little mind boggling knowing the DDC pump ran my entire loop in my SM 8 with longer tube runs and not on my test bench.
If anyone can help with my problem, I would greatly appreciate it.

A short video would make it pretty easy to diganose.

What fluid were you running in the loop prior to disassembly? Check your waterblocks for cloggage.

D5 pumps can be hard to clear the air out of when first installed dry, you may need to move and shift it around to break up the air in it before it can build the suction to pump water.
 
I am assuming you have the intake/exhaust ports correct and checked to make sure it's vibrating when powered. But it's probably the air pocket in it, I own a D5 that's 13 years old and still going strong. Always takes mine several power cycles and gentle shaking to get it entirely clear of air whenever I drained the loop.

I've tried moving my test bench around, turning it back and forth and yes, all my inlets and outlets on the blocks and pump are connected right. I can hear either pump turn on and feel the warmth coming off of them. When I uninstalled everything from my case and although the waterblocks looked in decent shape to begin with, I took them apart to manually clean them.

I've been watercooling for years and this is the first time I've had any trouble priming loops. I'm going to fiddle around with it tomorrow after work. I appreciate the help Kougar and a213m.

Maybe - one of your plugs or fittings it too long - it may be blocking the fluid at that point - in your loop

If you have the pump on long enough length of hose then raise the D5 above the system, any amount you can - it should gravity feed through the pump - as long as the air can escape - from a high point in the loop.  (your using the top of your reservoir as the return, might want to move / (remove) that, at least temp for a quick test)
 
I know that EK CPU water block Is Directional --> the flow only works one way

My D5 powers My build Nibbler - 3 - GPU, CPU & 2 Radiators - those pumps have plenty of pressure
 
Tests:
- pump to bucket - distilled water
- take CPU out of loop - does it flow ?
- take GPU out of loop - does it flow ?
 
 
 
 
 

Thanks Cool GTX, I will check the plugs. However, I did try to gravity feed the loop as well without any luck. Would only feed a certain distance, to the CPU block and stop.

Come to think about it, I have a water temp plug connected on the back side of the pump. Maybe to long and is stopping the pump propeller. I'll look at it tonight after work and keep you posted with results. Thanks again Cool GTX.

which part number - Singularity Computers & D5 pump reservoir combo

https://www.singularitycomputers.com/shop/watercooling/protium-150-d5-reservoir-combo-acetal-stand-alone/

Also, I was curious and checked the water temp plug. Unfortunately, this wasn't the problem. Would you think a 90 deg fitting from the pump out port would restrict the flow in any way? When I had it in my CaseLabs SM 8 I had the same setup but longer tube runs. It's odd that both the D5 and the DDC pumps are doing the same thing.

No - the 90 should not cause an issue, even if you have several of them
 
EK - does warn about "long threaded" fittings - have the ability to block ports