Water pump hell

Ok, I've had this water cooling rig for two years. This weekend, I took it apart, cleaned and reworked it.

The problem:
It won't circulate on its own. Once I get it going, water flows. If I turn it off and back on, no flow. I have to use valves and blow air backwards into the system. Then it surges back. I open my valves and it continues to flow. It's the damnedest thing.


Changes:
The tube that went from the pump to the CPU had a split up the middle inside the resivior. I replaced it. The pump has a stock fitting epoxied and a hose of the same size clamped to it.

The propeller on the pump had wiggle room. It was made with slack in it. I epoxied it as I had read somewhere that it may help quiet the pump. I don't think that it did.

Kinks were replaced with 90 degree elbos. Not ideal but better than kinks right?

Everything else is the same as it had been for the last two years.

Thoughts:
Perhaps the pump needs the slack in the propeller?

Maybe the new hose that is clampped to the pump is somehow creating too much backpreasure? Perhaps the split in the old tube allowed it to work?

The system:
The system is a submersible pump in a gallon container. It has a rated 'head' of some 5 feet.

It goes from pump > CPU > GPU > Radiator > resivior.

The system is clamped from start to finish. The return line in the resivior dips far into the water to reduce the 'waterfall' sound.

The system is self contained INSIDE a full tower case. The pump sits at the very bottom. The radiator is at the very top, about 2.5 feet up. The CPU block is about the same hieght as the outlet of the resivior. The GPU is below that and then the water goes all the way up to the radiator. It worked before.

what pump do you have? (or did I miss that somewhere)

You didn't miss it. It's a generic fish tank pump. I don't recall the brand but it was the biggest that I could find. 5 foot head, 300 gallon/hour. It's a mag drive. In other words, the only moving part is the propeller shaft.

I'll get the brand and model later today I hope. I'm going back to the place I bought it to get a new shaft/propeller.

I just don't know if that will help or not.

It's an Aquclear 4000. 422 Gallon/hour, 5 feet.

It's made by a German company called Hagen.

Could be the magnets or a stuck impeller. I don't know what yo mean by epoxying the propeller, but I'm pretty sure that would TOTALLY freeze up the flow. One last thought is there might be an air bubble in the pump. You may try flipping the pump over while it's on. Don't know much about pumps, just an idea.

I think he means like people do to via pumps to quiet them down. It could be the pump going, you did say it was a generic type that is 2 years old. Eitrher its that or the epoxy you put on there is messing up the pump. The reason people do it to the via pumps is they have a free moving propeller that moves up and down. The epoxy stops it fro mmoving up and down from what I understand.

The reason people do it to the via pumps is they have a free moving propeller that moves up and down. The epoxy stops it fro mmoving up and down from what I understand.

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This is what I did. I called the company, they have no answers but now I have the terms. It's called an impeller. I glued the impeller to the magnetic impeller assymbly. It makes it one unit. This unit then slides down over the spindel. I made sure that the epoxie was dry long before I put it into the pump houseing. Spins freely.

Note: It moves water once I manually start it going. It has been running now for two days. I just can't turn it off. If I do, I will have to manually start it going again.

Is the water submersible? It sounds like motor-start capacitor blew. These are usually the first things to go in motors I believe. If you know how to trace electronics, you might check the capacitors.

One of the quirks about mag-pumps, the type with half of the motor in the water(the magnets) and other half (the windings) in a watertight cast, is: In the first moment when the pump is powered the motor tries to decide which way to go, it wiggles sideways in both directions until it tips over the peak to one or the other side since it wiggles more on every turn. That is the short rattle you usually hear when its starting.

If you glue the impeller shut on the axle and does not allow free movement of the axle, it has to wiggle with water resistance and that MIGHT stop it from gaining the needed momentum to pass the peak before beginning on the next half revolution.

The free movement of the impeller is there for a reason, I can't understand why people glue it.... unless it has broken of coz.

Or... you might have too weak magnets, might be worn out somehow. The enemys of permenent magnets is heat, mechanical shock or strong reverse magnetic force.

i think paxmax got it down

people glue the impellor because they want to reduce noise but think about it.
if companies thought that the empellor should not move then they would design it that way and we wouldnt need to glue it.
so basicaly you may be SOL and need another pump

In the first moment when the pump is powered the motor tries to decide which way to go, it wiggles sideways in both directions until it tips over the peak to one or the other side since it wiggles more on every turn.

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Paxmax, you are the best. MAn did you just spark a huge light in my brain.

That explains why I have to blow air backwards through the system. When there is no more water in the pump, it flips over. Then it gushes out of my valve until I close it. And I mean it really has some force when it starts.

Man do I feel good about this. Thanks. And thank you to everyone else who replied.

Man did I ever learn something here. Sahhweeet!

so basicaly you may be SOL and need another pump

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Fortunately I'll be ok. The pump is $50 US but I can get a new part from the factory for $22 with shipping. I may also go to ebay. It works as long as I don't shut it off.

you may be able to UNGLUE it if you are careful and save yourself some money ( i wouldnt try it uless you are very steady with a knife or exacto blade)

After a couple of days, some epoxies are softened in water...you might try to pick the epoxy back out of it. Plastic is a real bear to get anything to stick to long-term.

I just went to ebay and got the entire pump for less than the parts. I should have it in a couple of days. The epoxy I got should be on there pretty tight. I'm not going to even mess with that.

Thank you all.