Ulka pump seems to mute during brewing

Equipment doesn't work? Troubleshooting? If you're handy, members can help.
AndersHP

#1: Post by AndersHP »

My Izzo Vivi pump (Ulka Type EX5) seems to buzz fine, up until mid-brewing, and then it seems to silence/mute down to maybe 20% sound, while still providing some pressure, though I'm guessing not exactly full pressure. It seems to influence the flow.

I just bought a new grinder and cannot get consistent shots when the pump does this, so I tried disassembling the Ulka pump.

The small balls, gaskets and springs inside seemed OK, but I can see that it's the original pump from 2010, so it's nearing its 12 year birthday. I just ordered a new pump, but is there something else I should replace/inspect that could be causing this mid-brew pressuredrop, other than the pump?

Nate42

#2: Post by Nate42 »

That's a pretty common symptom of a dying pump, and 12 years is pretty old. I've never had any luck repairing one, for me at least replacing it is the only thing that does the trick.

I think it's safe to assume that's your problem, and even if it turns out something else is also wrong, the pump was going to fail sooner or later and replacing it makes sense.

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GC7
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#3: Post by GC7 »

I had that problem with my old QM Anita. The pump would go silent under pressure during a shot or backflush.

Like you, I purchased a new pump that remains sitting in my drawer. On the advice of EricS, I replaced the old worn expansion valve rubber seat. It solved the problem. I'm guessing that it hardened and was stuck in place. For a $5 part that needs replacing every couple of years as routine maintenance anyway, it's worth having on around.

AndersHP (original poster)

#4: Post by AndersHP (original poster) »

Nate42 wrote:That's a pretty common symptom of a dying pump, and 12 years is pretty old. I've never had any luck repairing one, for me at least replacing it is the only thing that does the trick.

I think it's safe to assume that's your problem, and even if it turns out something else is also wrong, the pump was going to fail sooner or later and replacing it makes sense.
Thanks! I was worried it might be the one-way valve but I cannot get to it, so fingers crossed the new pump will help :D
But how come the pump looks fine on the inside if it's probably about to die?

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cafeIKE
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#5: Post by cafeIKE »

Have you checked the thermistor? The pump is under the boiler and if the thermistor is on top next to the boiler, it could be causing a problem. You may want to add some insulation between the pump and the boiler.



If there is a bleed valve in the water circuit replace that as well and make sure the outlet points up.

Also recommend getting the 52w rather than the stock 45w

AndersHP (original poster)

#6: Post by AndersHP (original poster) »

GC7 wrote:I had that problem with my old QM Anita. The pump would go silent under pressure during a shot or backflush.

Like you, I purchased a new pump that remains sitting in my drawer. On the advice of EricS, I replaced the old worn expansion valve rubber seat. It solved the problem. I'm guessing that it hardened and was stuck in place. For a $5 part that needs replacing every couple of years as routine maintenance anyway, it's worth having on around.
The expansion valve in the e61? I already replaced all the 3 valves inside the grouphead.
If it's not what you mean, I'm not quite sure where/what it is.

AndersHP (original poster)

#7: Post by AndersHP (original poster) »

cafeIKE wrote:Have you checked the thermistor? The pump is under the boiler and if the thermistor is on top next to the boiler, it could be causing a problem. You may want to add some insulation between the pump and the boiler.

If there is a bleed valve in the water circuit replace that as well and make sure the outlet points up.

Also recommend getting the 52w rather than the stock 45w
I guess the thermistor problem would make the pump shut down completely, which is not the case. It's still audible pumping, just not as much.

I'm a bit out of my league here - could you identify a bleed valve in this diagram?

https://www.kaffemekka.dk/upload_dir/sh ... eparts.pdf

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cafeIKE
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#8: Post by cafeIKE »

The thermistor will not make the pump shut down. The thermistor is a variable resistor and and just the right temperature, the pump will run as described.

There is no bleed valve in the exploded diagram.

You should check the bypass return to the tank when the problem occurs to rule out a faulty OPV, # FE304 in the dwg. There should be a flow from the return line [TF 49] until the pump gets quiet and none after. If it is otherwise and the flow gets stronger, the OPV is leaking.

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GC7
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#9: Post by GC7 »

AndersHP wrote:The expansion valve in the e61? I already replaced all the 3 valves inside the grouphead.
If it's not what you mean, I'm not quite sure where/what it is.
https://www.chriscoffee.com/products/ex ... ement-seat

It is the seal on the expansion valve that sets the brew pressure. My guess is if your pump and machine is that old and you don't know what this part is than it has never ben replaced. Chris had a nice video on how to replace it. You should do so regardless of the possible pump issue.

AndersHP (original poster)

#10: Post by AndersHP (original poster) »

cafeIKE wrote:The thermistor will not make the pump shut down. The thermistor is a variable resistor and and just the right temperature, the pump will run as described.

There is no bleed valve in the exploded diagram.

You should check the bypass return to the tank when the problem occurs to rule out a faulty OPV, # FE304 in the dwg. There should be a flow from the return line [TF 49] until the pump gets quiet and none after. If it is otherwise and the flow gets stronger, the OPV is leaking.
OK, the OPV I can get to, see photo below. I can easily remove the top part, but the bottom I cannot. It's so tight, I'm afraid of bending the small copperpipes below it. Can I get to the rubber seat that GC7 mentions by removing this top?



I cannot see the thermistor on the Ulka pump, it looks like this, and the boiler is on top of this. But the problem also happens when the boiler is freshly turned on, not only after hours of use (FWIW). Is the thermistor incorporated in the wires? They show no sign of anything and ran along the pump side.