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Does my pump sound OK?

Sometimes on depressing the lever to start pulling a shot my pump doesn't make the usual noise, instead it makes a kind of electrical buzzing noise. Below is an example, where it starts buzzing after the initial activity. Normal or cause for concern?

Pump is set to 10ms delay. For this shot PI pressure was 3.5.


  • hi rob

    yes, its not ideal. on the very bottom of the pump, hanging out through a hole in the bottom of the chassis, you will find a pressure adjustment screw for the pump. turn this screw fully home (closed) then turn it out two full turns. does that help?

    kind regards

  • Hi Reiss,

    I turned the screw in as far as I could - it recessed inside the chassis so I could not turn any further - and then out two turns again. The previous setting was at least an additional full rotation further out, likely more. I presume this means the pump was previously at a relatively low pressure? If I have understood correctly screwing it in increases pressure?

    After making this adjustment it certainly sounds more healthy in operation this morning - no prolonged buzzing. I'll see how it goes with additional usage as the occurrence was intermittent. Thank you.

    Out of curiosity, why do you think the pressure setting was causing the buzzing?

  • The pump is still occasionally making these buzzing sounds. Today I tried a shot with 6 bars (light roasted beans). When I pulled down the lever the pump did not engage and just buzzed for 5-10 seconds before starting to work. I tried another shot and it engaged straight away. Any ideas?
  • Any ideas? Seems interesting that the issue occurred more significantly at high PI pressure. Never occurs when there is no resistance when flushing. I presume this suggests some sort of issue with the pump? Making things a bit inconsistent at the moment.
  • hi rob

    yes it will be sticking when the vanes in the pump come to rest in a certain point where the pump liner is slightly roughened, the result of it having run without water at some point in the past

    unless you are in the mood to replace the pump i would just run with it

    kind regards

  • There was one occasion when the tank ran dry and ran briefly without water.

    How big a job is it to replace the pump? I'd rather have the machine functioning in tip top condition. I don't mind the cost of a new pump to get that, especially if the replacement process is simple. If more complex possibly I could call on some of the CFUK forum members for some more skilled mechanical assistance.
  • My earlier LR with that same pump (now at my girl friend's place) had that occasional buzzing as well. I took care to switch it off and on when it was heard so the 'sensitive' spot could not burn in more and after a while it just was never heard again. I think it helps to ensure that the water reservoir is never empty so the pump is not made to suffer and gasp for water.
  • Rob West post=17116 wrote:
    How big a job is it to replace the pump?

    Assuming you feel comfortable with tools, fairly straightforward. I did it once on the machine that my son-in-law has.
  • Rob West post=17116 wrote: There was one occasion when the tank ran dry and ran briefly without water.

    How big a job is it to replace the pump? I'd rather have the machine functioning in tip top condition. I don't mind the cost of a new pump to get that, especially if the replacement process is simple. If more complex possibly I could call on some of the CFUK forum members for some more skilled mechanical assistance.

    hi rob

    first check that there is a short (about 40mm) length of silicone tubing pushed onto either one of the two low water electrodes in the bottom of the water tank, as show in the image below:


    this silicone tubing has been added to provide extra insurance against the pump being able to suck the water tank dry before the low water alarm turns the pump off

    changing the pump is not difficult if you already own a set of basic hand tools and are comfortable using them

    - a small number of metric combination wrenches
    - a set of metric allen (hex) keys
    - a pair of long nose plier
    - i think that's it

    i am also available on FaceTime video or WhatsApp video to do the pump swap with you

    in essence the steps are

    1. unplug the machine from electrical supply
    2. remove the plastic water tank, top, left, right, and back panels from the machine
    3. trace the white and black wires down from the top of the pump motor to the spade connectors on the end of each wire where they plug into the wiring loom and take photos of the connections before you unplug them (although strictly speaking it is an AC motor so the polarity of the wires does not matter)
    4. take a pair of long nose pliers and gently compress the end of the stainless steel wire jubilee clip on the pump inlet that secures the clear silicone inlet hose, and wriggle the stainless jubilee clip off the pump inlet and down the silicone inlet hose (personally i take the stainless wire clip off and throw it away as it is a curse to get on and off and is not needed as there is no pressure on the silicone inlet hose as it is only gravity fed by the weight of water in the reservoir)
    5. take a 13mm combination wrench and undo the braided stainless steel pressure hose from the pump outlet
    6. then take your allen key and undo the 4 cap screws that secure the pump to the frame; you will probably need to push the screws right out and also the rubber grommets as you need to create as much space as you can to get the pump out, typically backwards and upwards, which is why you need to remove the back panel
    7. fit the new pump and mount the 4 cap screws to hold it in place, and reconnect the two pump wires to the wiring loom
    8. reconnect the braided stainless steel pressure hose to the new pump, taking care to ensure that you do not induce twist in the hose as you tighten it up, otherwise the hose will crimp and the pump will not be able to deliver any water to the machine (this is important to note as it happens very easily)
    9. hang the silicone inlet hose for the pump into a bowl with at least a couple of litres of capacity and then refit the plastic water tank into the water tank carrier and half fill it with water: water will immediately start to pour out the end of the silicone inlet hose and into the bowl you have it dangling in. once the air has bled from the line (this will happen after 5 seconds of flow) take the end of the silicone inlet hose from the bowl and quickly push it onto the inlet spigot on the pump, refitting the jubilee clip if you choose to retain it
    10. pull the lever into the fully locked down position on the cam and leave it there, being aware that if you catch your shirt sleeve or anything else on the lever it will fly up and whack you in the face with considerable force and the resultant harm may be considerable
    11. with dry hands, turn the machine on; after a brief delay the pump should turn on and shortly after that water should start to pour from the shower screen; this is your que to raise the lever out of the locked down position up to its 'beyond vertical' resting position, which will cause the pump to turn off as the target pressure will be quickly reached when the piston returns to the down position in the group (lever up)
    12. leave the panels off the machine and the machine on for say 1 hour to check for leaks, keeping children and others away during this time
    13. refit panels

  • Thanks Reiss, very clear instructions as usual. Less involved than I thought it would be.

    I do have that piece of silicone tubing. I can't recall the exact circumstances but I think there was some combination of pulling a shot and boiler refill. Since then I've never let it get below half a tank.

    Wish me luck for the operation and let's hope the patient pulls through!
  • priming the pump before you start it is the key bit; bleeding the air from the feed line line and then pulling the lever into the locked down position so there is no pressure on the outlet side of the pump to make it harder than it needs to be for the pump to make that initial pull of the water, and then you're away.

    if you simply turn the pump on without taking those steps you run the risk of the pump just spinning at high speed in air with no load on it, no lubrication from water, and the pump liner quickly being damaged as a result, and a brand new pump is toast.

    kind regards

  • Hi Reiss,

    Hit a bit of a snag with the new pump. The nipples for the water feed are not the same size. I have attached a photo. I got all the way to the point of attaching the hose when I realised. There is no way the existing hose can be attached.


    For now I will attempt to fit the old wounded pump back in the machine. How would you suggest to proceed?


  • Looks to me like it's very easy to take off both nipples and fit the one yoiu want to use on the pump you want to use it on?

  • Hi Frans,

    I had the same thought, but just wanted Reiss to confirm. I don't know if those copper washers would still be OK to use. Old pump went back in OK until then.

  • I've re-used copper washers like that. If one does that repeatedly they tend to get hard and lose their softness (but in that case a gerenal tool/hardware /plumber store has them) but I'd fasten them hand tight and then hit the spanner once with a hammer for that extra bit. You will notice soon enough if the washer leaks a tiny bit. And you have two, one off each pump, to try ;-)
  • hi rob

    let me check with the factory as my instinctive preference would be first try and stretch that silicone hose over the nipple, using a little loxeal grease on the nipple if i had to. failing that i would be looking to fit a slightly larger diameter of silicone hose, but this might necessitate having to put a larger nipple at the tank end, which may not be readily available

    conversely the factory might say it has been fitted with the incorrect fitting and simply swap it out with the original nipple

    kind regards

  • Hi Reiss,

    Any response from the factory?


  • hi rob, no but the guy i needed to ask was on holiday last week apparently, but is now back so i have sent another email just now
    i will let you know later today with any luck
    kind regards
  • Thanks Reiss, will look forward to what they have to say.

    Re. our conversation the other day, still getting intermittent water alarms. Just now it happened when I pulled the lever down for a shot so that the pump did not come on. Pressing down/jiggling the water tank stops the alarm. In this case I raised the lever, jiggled the tank so the alarm stopped and then pulled the lever down again. The pump did run initially before stalling again.

    Could this be related to the pump in any way? In your water alarm post ( in 1.4 you mention the pump. The brass probes look fine. I remove and clean the water tank on a fairly regular basis (roughly monthly) and have never had an issue with a water alarm from improper seating before.
  • Rob West post=17155 wrote: I remove and clean the water tank on a fairly regular basis (roughly monthly).

    I would leave the water tank where it is, and if you have not immersed dirty hands in the tank water and if you fill it with clean water from a clean jug, there is no reason to take out and plug back in the water tank.
  • hi rob

    the word from the works manager is this is the nipple they are fitting the pump with now and he assures me that the existing silicone tubing will fit over the larger diameter nipple

    i have written back asking if there are any factory tricks on how to coax the tubing over the larger nipple and i will pass on his advice if he has any

    as far as the water alarm sounding is concerned i do list all the possible causes in the post you reference above

    if the brass electrodes below the water box are not corroded then it will be one of the other causes i list

    for example, depress the brass electrodes and check that they both pop back up quickly, as it is not unheard of for them to get stuck down or not fully recoil as they age, which reminds me i must add it is as a parts set to the website

    other things that can happen is the bottom of the water box distorts with age and arches upwards (concave) and as a result the stainless pins in the bottom of the water box are no longer perpendicular and they no longer have contact over their full surface area with the brass electrodes beneath them. this can be alleviated by pushing the stainless pins down by a millimetre or so

    kind regards

  • ps the low water alarm is only 'connected with the pump' in the sense that it will sound if the pump fails to raise the level in the boiler to the maximum mark on the level probe within i think 25 seconds, a number like that anyway, so if you pump if not delivering water into the boiler with the blue light is on (solenoid open) you will indeed trigger the water alarm after a period of about 25 seconds

    kind regards

  • I think I might have both issues you mention with regard to the water alarm. One of the brass electrodes can catch when depressed so that it does not pop back up. My water tank is also ever so slightly concave. I've tried to push one of the electrodes down a bit as it was slightly less proud (the one that contacts the sticky brass electrode). Hopefully that will do the trick.

    If the person does have any hints or tips for getting the tube onto that nipple I've be much obliged. When trying it with the expansion valve return tube and Loxeal I got it on a 5mm or so, getting it any further was the issue. Do they also use exactly the same circlip with these wider nipples? I know you mentioned that this clip isn't really necessary, I'd just be concerned if I cannot get the tube all the way on that it might come loose. Is 5-10mm enough do you think?
  • I should also say that I have had no issue with boiler refill. The alarm has not sounded when the blue light is on. It seems to happen more when I go to pull a shot or flush the group.
  • 10mm will be enough for sure as it is only holding the water pressure of the depth of the water in the water tank

    usually if you can get something like that on 10mm it will keep going on, even if only at 1mm each time you make a stretching push of the silicone tubing up the nipple
  • I'm pleased to report that I did manage to get the tube onto the new pump. I have to admit that it wasn't nearly as tricky as I thought it would be, and eventually I got it all the way on. The clip is too small to go back on, but not an issue as you said. Wish I'd removed it before attaching, but it can just live on the tube for now.

    The new pump is a huge improvement. It sounds completely different and much quieter, even against the normal operation of the old one. I can pretend I have an LR24 :-)

    Thanks for your help.
  • good stuff rob. thanks for letting us know. reiss.
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