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Thread: Rebuilding a Rancilio S27, might have used too much citric acid?

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    Rebuilding a Rancilio S27, might have used too much citric acid?

    I'm rebuilding a Rancilio S27 that I bought used. It looks very well kept on the outside, but the tank and showerhead were pretty bad. I don't think the previous owner has ever done any backflushing or descaling, even though the machine apparently had only very light use. I'm a bit concerned I used a bit too much citric acid on the tank and some of the bits. The tank came out with most of the scale removed, but there's a slight white 'powderish' coat on the element, and some parts got a bit of black sludge, which I suspect might be from a screw that inadvertedly was in the descale bucket. Possibly an aluminium screw. Am including some pictures of before and after.

    Should I have not descaled the element this way?
    IMG_20171012_101319.jpgIMG_20171012_100944.jpgIMG_20171012_114430.jpgIMG_20171012_114436.jpgIMG_20171012_234046.jpg

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    Added a few more 'after' images as I hit the limit.

    IMG_20171012_234058.jpgIMG_20171012_234123.jpg

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    Senior Member LeroyC's Avatar
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    Looks ok to me. The two things you want to look for are any remaining loose material and damage to the element. The appearance of the inner surface of the boiler doesnít matter too much as long as youíve removed all the scale and sludge as this can migrate and block pipes and valves when you start using it again. The element is the biggest risk as even a pin sized hole can mean its stuffed. Test it for continuity if you can then youíll just have to see how it goes. Looks like the previous owner didnít use filtered water.

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    The element tested at 32ohm both dry and in water, so seems ok. I did another bath for the element and the tank with a bit less citric acid and it came out better. I should probably try to remove the HX loop as well? It's too large for my largest wrench so I haven't got it off yet. The machine has been used with a filter, but it might be old. There was also an MD 40 grinder with it with a counter at about 3200, I guess that might be the number of doses it has ground in its life? The tank has a stamp R016, but I'm pretty sure it can't indicate 2016. The water filter has a sticker with some illegible number. It might seems to indicate '06 on it. So much for maintenance..
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    Senior Member LeroyC's Avatar
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    To be honest I actually think itís in pretty good knick. Iíve seen a lot worse even with my very limited experience. Youíll never know until you try it, but Iím thinking itíll be all good.

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    Mal Dimal's Avatar
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    Yep, agree with Leroy...

    Mal.

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    I wouldn’t take out the HX tube (The risk is you night break the tube) but rather one you reassemble run some citric acid thought the hx system and at the same Time you will also descale the group head. These things are built like tanks and great machines! Where are you located?

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    I'm up at the sunshine coast. I got a new showerscreen and group seal, and it's been put together and I think it's ready for use. I don't currently have an available water tap, so I was going to try with a tank at first, but how do I prime the pump to get it going when there's no water in the hose at the moment? When I turn it on I can faintly hear the pump going and it's vibrating slightly, but I don't think there's any water drawn. I prefilled some water in the tank to avoid the element from overheating, but am not sure how to do this with a rotation pump.

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    I'm pretty sure now that water is getting to the pump, but nothing is coming out of it. Is it safe to separate the pump from the motor, to see if the pump bit is jammed up?

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    Yeah it’s ok to take the pump off the motor. You might find that the pump may have sized up. You can’t connect the water pump to a mains outlet at all? It might just a little bit of help to start.

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    Senior Member LeroyC's Avatar
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    How long is your garden hose?

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    Ok, I got it plumbed in temporarily, and got water pressure at the pump, but it's still not going. I took the pump off the motor, and I can make it rotate slightly just by hand force, and fairly easily with pliers. How easy should the pump be to rotate by hand force? The motor doesn't run even with the pump on, and I've measured 230v on the cable going into it. Am suspecting either a faulty capacitor or the stators itself. I opened up the motor and it seems a bit rusty on the rotor bit. Am wondering if it could just be the rust causing an issue here? Also, how do you go about removing it? Just with some aluminium foil, or some sort of chemical rust remover?
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    Also, does measuring the capacitor while in circuit with the motor make any sense as to wether the capacitor is faulty?

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    Mal Dimal's Avatar
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    Quote Originally Posted by iampivot View Post
    Also, how do you go about removing it? Just with some aluminium foil, or some sort of chemical rust remover?
    With a wire brush is the best bet and then coat it with a thin coat of quick drying varnish to prevent future rust...

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    Mal Dimal's Avatar
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    Quote Originally Posted by iampivot View Post
    Also, does measuring the capacitor while in circuit with the motor make any sense as to wether the capacitor is faulty?
    Disconnected from the circuit is best...

    Mal.

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    Will update you with some pictures of my L4 (has a old thread here somewhere) which looks much worse then your images

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    I got the rust off the rotor with some aluminium foil, but the rust inside on the stators will be a bit more tricky. Will see if I can get a wire brush later to do those, and then do the varnish. It started after that, and there's water pressure! But now there's a few other things that seems not to be working. The heating element is not turned on. There's no voltage across it. It measures 32 ohms still. Also, there's no water coming out of the group-head when pressing one of the brew buttons. I might have put the three way solenoid back on the wrong way. Will check that tomorrow.
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    Had a quick look at the L4 and I think I like the subdued look of it better than the S27s silly side panels.

    I noticed that there's quite a bit of water coming through the pump even when it's off, is that a sign that I might need to reduce the water pressure coming into the machine with a pressure limiter?

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    I found this extremely helpful thread that reminded me the thermostat needed to be reset; Rancilio S24 Heating Element Replacement Tips (with pictures)

    So now it's heating up at least!

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    Rotated the three way solenoid the correct way and now I've got water coming through the group-head! Just need to try to get the hx loop descaled as it sits now.

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    Quote Originally Posted by iampivot View Post
    I got the rust off the rotor with some aluminium foil, but the rust inside on the stators will be a bit more tricky. Will see if I can get a wire brush later to do those, and then do the varnish. It started after that, and there's water pressure! But now there's a few other things that seems not to be working. The heating element is not turned on. There's no voltage across it. It measures 32 ohms still. Also, there's no water coming out of the group-head when pressing one of the brew buttons. I might have put the three way solenoid back on the wrong way. Will check that tomorrow.
    Whilst you have it apart put a new start capacitor in, looks like it's a 5uF, 450V one by the label on the motor. They aren't expensive & do eventually go, so doing it now can save you changing it at a later date.
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  22. #22
    Mal Dimal's Avatar
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    If you want to use a wire brush inside the stator, then it would have to be a fairly small one to ensure that you don't accidentally damage any of the winding insulation. Need to be careful...

    Mal.

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    To descale the Heat Exchanger. You need to remove the boiler fill prob and allow the boiler to fill with fresh water. (This iss to prevent the boiler calling for water when you have your descaler solution in mixed as you don't want to contaminate the boiler with your descaler) Once you have over filled the boiler with the fresh water place the inset connector back onto the probe and then place your water inlet hose into your descaler and then flush 100ml or so of the solution through the group. Let it set for 5 to 10 minutes and repeat the process. Once you have done this reconnect the fresh water supply back in and flush the group with around 500ml-1000ml of water and you will be done.

    The when the Rancilio's are new it takes around 7 seconds to get 80ml of water out of the group head. If your machine is doing this now then there would be no need to descale the HX.

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    Here's the flow rate now;

    Based on your statements I wouldn't need to descale the HX with this flow rate?

    It's quite noisy, am wondering if it's the motor that needs some more work.

  25. #25
    Mal Dimal's Avatar
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    Nothing wrong with that flow mate...
    I also think that with the covers off, that's not really very noisy either.

    Mal.

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    Quote Originally Posted by iampivot View Post
    Here's the flow rate now;

    Based on your statements I wouldn't need to descale the HX with this flow rate?

    It's quite noisy, am wondering if it's the motor that needs some more work.
    Was that a 30ml shot glass? Might be best to descale it? You have come this far.

    Noise is a little loud is the pump vibrating?

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