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Low pressure on the brew group


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Hello, I have a Alex Duetto from 2008. Has been serviced regularly. Although last time was now about 2 years ago. I was considering to start doing more myself. Anyhow I have a low pressure on the brew group. About 4 bar when it is running against a blind cap.

Initially when I lifted the brew lever brought it down and lifted it again it would get the right brew pressure. Now it remains a 4 bar.

I contact my regular service shop. The adviced me to clean the no return valve and turn the pump OPV 360 degrees back and forward. I did both but still low pressure

Edited by Raoul
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Hi @Raouland welcome to the forum.

You need to lubricate the cam in the brew group, that's a loud squeak when moving the lever. I assume you recently backflushed with cleaner? if you didn't, you need to check the lever cam pins, especially if the lever feels "notchy" or hard to move.

As for the low pressure, the pump and motor sound OK, so it may well be the balanced bypass in the pump sticking, scaled up or damaged in some way. Can you post a photo of the OPV you adjusted as advised by the shop, just so I'm sure I know what you adjusted?

It's also possibly that the start run capacitor on the RPM motor needs replacement, as these can fail and either not allow the motor to start all the time, or they start and run with quite low RPM/Torque. We will soon find out what the problem is.

Yours looks like a MkII or possibly a MKII.

899161310_ricehaiku.JPG.d69e44c11eab9645400547eea500ba1c.JPG

 

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Great to see a 13 year old machine looking in such great condition 👏 & also great that we've got such good techy advice on here. Hopefully I'll have one soon. 

Hope it's an easy fix. 

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@Raoul Yup that's the right screw...looks like someone's not been kind to the acorn nut outside...did someone screw it all the way in with a big screwdriver?. Before you start going big on repairs, is your water hard or soft and how do you treat the water going into the machine.

OK..

  • Run the machine and think of the pump motor sounds slow and does it ever fail to start
  • capacitor on the right...is that dirt or burns, you can get a new one on the bay for about 10, just get the right values. Give it a wipe  with a damp cloth and find out, (best to discharge it first)
  • Unscrew the adjuster, all the way and check what's inside all looks OK, be careful, you want to get it all back right or it won't work. You can use a bit of Moly on any sliding bits and O rings.
  • Unscrew the pump clamps and check the pump isn't leaking into the motor, a check you should do every year if you don't want to buy a new motor. if it is, get a new pump and push a bit of Molycote around the motor spindle each year

Is the pump head a FOT Rotoflow?

Edited by DavecUK

899161310_ricehaiku.JPG.d69e44c11eab9645400547eea500ba1c.JPG

 

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It's dust on the capacitor. Cleaned it. Hardness is 5.6 dH (i.e. 97 ppm), and connected to main via BWT best max filter set up.

The pumphead is a fluido tech. So I guess yes it's a FOT rotoflow. It says CA104Z, although I also see CA0120AGANN on the pumphead.

Looks like the first next step is to completely unscrew the adjuster. I don't have moly. Can I use another liquid libricator like WD40. Not sure if these are okay for use in an espresso machine.

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6 minutes ago, Raoul said:

Looks like the first next step is to completely unscrew the adjuster. I don't have moly. Can I use another liquid libricator like WD40. Not sure if these are okay for use in an espresso machine.

No, absolutely not for using WD40. Molykote 111 is the best to use, or similar.  In a pinch use WRAS approved plumbers silicone. If you invest in one tube of Molykote 111, it will last you the rest of your life.

https://www.univarsc.com/products/molykote-111-grease

899161310_ricehaiku.JPG.d69e44c11eab9645400547eea500ba1c.JPG

 

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5 hours ago, Raoul said:

I can't unscrew it with a screwdriver. Too tight. Does this mean I need to untighten the bold too? 

You can try, the acorn nuts not really meant to be undone and you still have the problem of getting the bypass screw out....dunno, it shouldn't be jammed in there like that unless it's cross threaded or screwed in really, really tight (which it never should be).

 

The other thing might be when the outside got chewed up, a burr or turned over piece in the thread is preventing the bypass screw from being undone.

Edited by DavecUK

899161310_ricehaiku.JPG.d69e44c11eab9645400547eea500ba1c.JPG

 

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I have looked at some tech drawings of the pump. If I remove the acorn nut, I can get the screw out at the other side as I can screw the adjustment screw easily in, but not out. That will most likely allow me to see what is wrong with the adjustment screw or the acorn nut.

Maybe a stupid question but do I need to take the machine of the main supply or can I leave it one and just close the main supply tap down. There is still 4 bar pressure on the system. I am wondering how much water will get out of the pump when I take the acorn nut off.

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I removed the acorn nut and didn't find too much problems.

Then tried to look into the motor. Got the clamp off, but unable to easily remove the pump. Should this be easy or is some force needed. I think I also see some scale already (see pictures)

 

20210414_215230.jpg

20210415_191705.jpg

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Anyone an idea how to get the pump from the motor. It is really stucked. No movement at all. Do I need to turn it or should I be able to simply lift it?

 

 

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It should lift out once the clamp band has been removed.  Try placing the end of a piece of wood against the pump body and gently tap the wood with a hammer.   Possibly some moisture has got between the pump and motor body.

Also try twisting the pump body.

Edited by El carajillo
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Had to give it up. Didn't manage to get the pump from the motor. Brought to the repair shop. Let's see what they find. Many thanks for the responses. It was an interesting first time experience to try to solve issues myself.

 

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