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Pump pulses for 1/2 a second

My LRs pump pulses on every few minutes for 1/2 a second, any ideas?


  • Thanks Reiss I will do this later when I get home.

  • Reiss reading the instruction it looks like this is for machine with digital pre infusion which I do not have. How do I tell how much to turn the expansion valve screw?

  • edited December 2020

    without the digital preinfusion the expansion valve will not be the issue

    it will either be the Mater pressure switch leaking (easy to detect), the piston seals leaking (usually the dripping can be seen from the group, but not always - it can be the middle seal), or the inlet solenoid is not completely closing, allowing water to escape through the valve to the boiler

    kind regards


  • edited December 2020

    I just put new piston seals on and re-greased everything. I also put a new mater switch in. Tomorrow I will take off the mater and put tape on the threads which I did not do when installing the new one. The manifold should be good because I took it apart as per your directions and cleaned it out.

    before I read ur previous post I did turn the screw on top of the manifold 1 turn clockwise, should I turn it back or just leave it.

  • edited December 2020

    It must be the selonoid, I will try and clean it again today. I think it’s the selonoid because while I was a work yesterday and the machine set idle al day not being used the machine started beeping in the late afternoon so my wife turned it off. I’m thinking that little by little all day the tank kept filling and the seeping was the machine overfill.

    is this plausible?

  • Cleaned out the selonoid again, tightened everything else and it’s still happening between every 30 seconds and 1 1/2 minutes.

    should I try replacing the selonoid?

  • try removing the non return valve from the bottom of the manifold and wrapping 5 or 6 turns of plumber's teflon thread tape to the top thread of the brass non return valve housing that screws into the bottom of the manifold

    to do this you will need; 19, 17, and 13mm wrenches

    the 19mm wrench you fit to the bottom of the manifold so the manifold does not bear any of the twisting forces as you use the 13mm wrench to remove the pressure hose, and then the 17mm to remove the brass non return valve housing; this is important or you will tear the manifold from the bracket that mounts it to the water tank carrier

    you can then add 5 or 6 turns of plumber's tape to the thread on the brass housing the threads into the bottom of the manifold. this has the obvious effect of holding the housing out from the bottom of the manifold by a couple of millimeters

    also take some photos of the inside of the brass non return valve housing where the o-ring on the jumper has to seal against it, otherwise you will experience the symptoms you report. the machined face on the inside of that housing needs to be super smooth (no ripples, waves, tool chatter, etc or it will not seal reliably). let me know what you discover

    kind regards


  • edited December 2020

    Reiss can you put up a list of all the wrench sizes needed for the LR, I would like to purchase a separate set just for the machine

  • edited December 2020

    Since I have the manifold and the pipes around the selonoid and mater off. Would it hurt to soak them in some descaling liquid? I have a feeling looking at the inlets into the boiler their is going to be some significant scale.

    and happy new year Reiss. Your in Australia right?

  • that is a good idea. also inspect the o-ring and check that the surface of the o-ring where it makes contact the with face of the brass housing still has integrity

    get in touch next week if your general clean doesnt solve it

    if you can open an account in for our new support system and raise a support ticket that would also be helpful as my plan is to make this forum read only next week

    happy new year


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