SOLVED Pump Issues - Loud grinding

A big thanks to everyone's input and advice! Another new pump resolved the problem.


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One would immediately assume this is air, but I really, really don't believe this to be the case.

I've been in contact with a very patient Gene from Monsoon, awesome guy. He mentioned air getting into the pump, and I really wish he were right. I've replaced the pump and the same issue presented itself. I guess I should start from the top.

While I was playing a game, the pump suddenly started to make a terrifying rattling/grinding sound before halting entirely. It would spin a few rotations and halt again, over and over. After taking a look at it, the bearing looked fine. The impeller plastic looked fine. There were scuffs on the metal of both the impeller and housing, as if it were damaged by imbalance. I could not get it to work again, so I ordered a new pump.

New pump came in, installed it, and ran it. Immediately the pump seemed excessively loud, but it got a bit better over time. 5 hours later, it did the same thing. Took it out, inspected, and the only thing I could see were again, scuff marks on the metal.

Huh.

I took the impeller from the new pump and put it in the housing of the old. It worked flawlessly and continued to for 5 days. Then the problem returned, but it seems to be a slightly different one.
It runs as if there's no issue until I launch a game. The overall temps increase and the grinding comes back, loud and rattling, sounding as if it's about to stop. When I exit the game the sound slowly subides as my temps return to normal.

What? I don't get it! I'm about to pull my hair out and I've been dealing with this for weeks now after 2 years of reliable operation. What the heck could be causing this?

Please help. Some details:

alphacool D5 pump
Monsoon dual bay res
koolance CPU-360
ek 1070 waterblock
koolance compression fittings
primochill tubing
some swiftek 360 copper rad

Only thing that makes 'scuff marks' inside the pump would be debris in the loop.

I must have put fresh distilled water in the loop about 4 times by now with all the trouble I've been having. What about these noises?

Did you take apart the entire loop and flush all the parts out or just drain and refill?

EarthDog said:

Did you take apart the entire loop and flush all the parts out or just drain and refill?

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Drain and refill. I will admit the first time I did so, there were blue flecks in the water. I later came to find it was from the plugs of the monsoon, a thin blue layer was peeling off. After the third time there wasn't any.

According to Gene just now, all the D5s he has have the same scuffs I mentioned, though he didn't comment on the rough spot while turning the impeller with my fingers.

Time to flush every part in your loop.

It's the only way to be sure there's nothing stuck in a rad or block somewhere.
Pics of the pump would be helpful too


Any chips or chunks missing from the propeller?

Pic of loop set up please. Also how it is run would be helpful.

Silver_Pharaoh said:

Time to flush every part in your loop.

It's the only way to be sure there's nothing stuck in a rad or block somewhere.
Pics of the pump would be helpful too


Any chips or chunks missing from the propeller?

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There doesn't appear to be. I was thinking that maybe my CPU block might be gummed up. I think during my weekend I'm going to dismantle the loop, take apart the cpu block to scrub it (have done so once before) and give the rad a good shake with vinegar.

The story changes a bit, now, because I turned the pump up to 3/5 and after a while the grinding came then faded, but a new problem surfaced. I haven't tried running a game yet to see if the grinding comes back. The new problem is that there's constantly air bubbles that won't bleed. Every so often a burst of air comes out of the impeller into the res, which I think definitely should NOT be happening. This leads me to believe there's more resistance than there should be to the CPU block. I might be wrong, what do you all think?

I'll take a picture of the loop soon, but for now the flow is:
res->pump->CPU->GPU->rad->res

The res is a dual 5.25" bay model from monsoon. The pump hangs off the back of it and draws from a hole at its center.

I'm leaning towards debris from the rad made itself to the pump, therefore you get the grinding noise. I'm using a D5 with my NZXT dual 5.25 bay res. My D5 is quiet as a church mouse on setting #3. I did have an older D5 that had a squeal tho.

Yeah your best bet is to flush everything out especially the rad. Clean the pump and res really good too.

There should not be air traveling from the pump to the res. If anything the pump should push the air through the loop and into the res from the rad. I'm not quite sure how this is happening as that means the air would have to flow against the direction of the water flow.

A picture of your case and loop would be really helpful.

after you flush the system you might try an antifreeze mix, antifreeze has lube in it that will help the impeller bearing.
I have had to replace the pump to res seal on the d5 pumps a time or two so you might order one and replace it while it's apart.
all the little "o" rings can deform and twist on the fittings and let air in or coolant out, try a little furniture polish on them, it's wax.

Mr.Scott said:

Only thing that makes 'scuff marks' inside the pump would be debris in the loop.

Click to expand...

Lochekey said:

There should not be air traveling from the pump to the res. If anything the pump should push the air through the loop and into the res from the rad. I'm not quite sure how this is happening as that means the air would have to flow against the direction of the water flow.

A picture of your case and loop would be really helpful.

Click to expand...

This.

As everyone said, we need some images of the internals to further investigate. To me it sounds like circulating debris and you want to find out if there's something going wrong with some of the gear that might be chipping away. A complete loop dismantle is needed.

I'm in the process of changing from distilled water and silver coil to a clear premix fluid (Aquacomputer) which is being recommended by majority of the big name water cooling companies. I would see you do the same.

I'm going to go with cavitation. Cavitation is the formation of vapour cavities in a liquid – i.e. small liquid-free zones ("bubbles" or "voids") – that are the consequence of forces acting upon the liquid. It usually occurs when a liquid is subjected to rapid changes of pressure that cause the formation of cavities where the pressure is relatively low.
As a note: Cavitation is NOT air in the system. It is low pressure vapor bubbles. The water is actually vaporizing because of the lowered pressure of the water.
You have a serious restriction. probably between your res and pump. I'm assuming that you have your pump speed linked in some way to your CPU temperature. When the pump ramps up it causes this low pressure zone.
Maybe a mis-manufactured fitting, hose or reservoir. Check that all the holes are machined clear without any obstructions. I had a GPU block cover where they didn't run the CNC bit deep enough and there was a clear plastic piece that I couldn't see blocking flow.
Try running you system with the cap off of the res. If the problem does not goes away then the restriction is between the res and the pump. If it does go away then the restriction is further up in the circuit.

Final edit: vapor bubbles implode at super sonic speed and can take chunks out of solid material which can cause scoring.

Quick update, I'm on my phone right now as I dismantle and clean everything. I already finished cleaning the CPU block, it was blocked up with what looked like moist lint with a few specks of metal, which was a little alarming. In any case I scrubbed her til shiny with vinegar.

I'm now soaking the rad with vinegar as I heat up some distilled on the stove. I don't have a funnel, pray for me.

After I'm done I'll take a picture of my loop setup and head for work, I will welcome input before I fill and leak test.

Also, sorry for the wait, and I appreciate all the replies. My weekend is almost here but I couldn't take the noise anymore, also it likely makes my pump just as mad as me.

Edit: I have attached some photos of my pump, I hope it helps for now. As you can see, the speed can only be adjusted manually.

Edit3: Added spoiler tag for all the photos.

Alright, I'm home from work, and I went ahead and remounted everything and filled it up.

Unfortunately, the pump is still making the same noises. At the "1" setting, it eventually quiets down after making a rattle and I guess, chugging sound? Kind of like a train. That eventually goes away.

But as soon as I dial it up a bit, say, 2- Griiiiinnnnd rattle grind. I swear it's as if the impeller is constantly dragging along the housing.

If I turn it up to 5, it grinds and halts, starts, grinds, halts, starts, etc

Edit:

I loosened the backplate of the pump (On the monsoon the pump is held in place by a large cylindrial shroud that pushes it against the unit by screwing it tight,) until it started to leak past the o-ring a bit, then I screwed it back down all while it was running. ...The grinding noise slowly subsided at the "2" setting. I fully expect it to eventually come back.

I'm starting to think this cavitation thing Thick8 talked about might be what's going on, but unfortunately I don't understand it well enough to really know.

I don't think cavitation left those marks in the pump body. Either debris or the impeller is hitting it. What does the impeller look like?

Alaric said:

I don't think cavitation left those marks in the pump body. Either debris or the impeller is hitting it. What does the impeller look like?

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There's a picture of it 2 posts above.

Can't really see the impeller itself. Maybe it's the lighting, but those look like some hefty, circular scratches in the pump body.

Another update.

I was able to get the pump speed to ~2.5 running silently since my last post. Tonight, I played CSGO with my friend, and about 15 minutes in, she starts to make an awful racket. Grinding, thumping, the whole nine yards.

So I took the cap off, still grinding away. I then turned the pump speed down to 1- It slowly faded and didn't return for the rest of the night. (About 5 hours)

Everything is flushed and clean, the o-ring is new, the impeller on the pump is 2 weeks old. The bay resevoir was purchased 2 years ago. Any ideas? What does this sound like to you guys?

I think the pump was damaged by debris in the system. Unfortunately I think the pump will have to be replaced.
That shiney part on that you see here..



is from rubbing on the housing. That cause unbalance and more rubbing.

I believe your only solution is another pump.