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Gaggia Classic - Flow stopping after heating up

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  • Xanthine
    replied
    Glad to hear you got it working Tim,
    Trev

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  • JojoS
    replied
    Glad all is back to normal. Keep in mind and adhere to a regular back-flushing routine and that new 3 way solenoid valve with thank you for it. FWIW, I backflush with water after each session before turning off the machine. Back-flushing with espresso cleaner every 2 weeks with the shower screen and dispersion plate removed and cleaned manually is also highly recommended. Keep it clean, keep it working as the late Tex of GUG would say.

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  • timjeffries
    replied
    Thanks!

    Thanks so much @Xanthine @JojoS and @LeroyC. Really appreciate your insights and support here. It's fixed!

    It was the 3 way Solenoid and I ended up ordering a new one as I wasn't confident messing with the electronics but it was pretty clear that was the fault.

    Again really appreciate your support and look forward to servicing my own machine from now on. This process has taught me heaps and given me lots of confidence. I might even replace the steam wand with the Rancilio one now.

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  • Xanthine
    replied
    Sorry, I guess I wasn't specific enough, but the solenoid I was referring to was on the 3-way and not the pump which appears to be working OK.
    Trev

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  • JojoS
    replied
    Duty cycle = the max time the pump is on followed by the rest time before it is turned on again. If I am following this thread correctly, this Gaggia Classic has not experienced any time of back flushing in the last 13 years. I suppose we should always start a trouble shooting thread with a maintenance history background first before trying a diagnosis. That said, the culprit is likely the 3 way solenoid valve and the passages in the lower part of the boiler. Detergent backflush is the most convenient solution and an important part of preventive maintenance before considering replacement. The pump is not seizing but probably reaches it's pressure setting as per OPV adjustment. If you take out the water reservoir and put two water cups with one filled with water going to the pump and the empty to catch the OPV overflow, chances are you will see the water flowing into it at the point when you consider the pump to be "seizing".

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  • LeroyC
    replied
    Yeah generally if you've got a good flow of hot through the steam wand but nothing through the group head it's not the pump. It can be the OPV or 3-way, but in this case as it seems to only be happening when hot a faulty 3-way coil is a definite possibility. You can buy the coil on its own as a spare part so definitely worth checking as described by Xanthine above. Good luck.

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  • Xanthine
    replied
    Hi Tim
    It could be that your solenoid coil has a heat sensitive fault.
    If you have a multi-meter you could try measuring it's resistance when cold and again when it is hot and the fault is occurring.
    You would only need to pull one lead from the coil to make the measurement across its terminals.
    I'm not sure what the reading would be when cold - probably 100-200 ohms but it should not be much more when hot.
    If it is very high - several thousand ohms or more it would indicate that the coil is going open circuit when hot and would need replacing.

    Just make sure you have the power off and the machine unplugged before you touch anything inside. If you are not confident working around mains voltages please do not attempt it.
    Also watch out for parts inside which could be quite hot.

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  • timjeffries
    replied
    Originally posted by JojoS View Post
    Please be aware of the recommended duty cycle of the vibe pump at 1 minute on and 1 minute off. Do you backflush? If you can, do you get a good discharge and a pop from the 3 way solenoid? You should pop the top off and do an ocular inspection to check if anything is loose. Unplug the machine before you do.
    thanks JojoS. I'm not sure what you mean by duty cycle? I recently bought a blind filter to try back flushing so will start that regularly when this flow issue is fixed. I have just had the top open, I stripped it right back and rebuilt it. Sadly the problem was still there after the rebuild.

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  • timjeffries
    replied
    Originally posted by LeroyC View Post
    When you say it 'seizes', do you mean there's no flow or a reduced flow? If it's no flow at all it's probably just an air lock and should be able to be rectified by running water through the steam wand to prime the pump. If it's a low flow problem then I'm not sure. It sounds like you leave the machine on for extended periods of time. This is not good for small machines with aluminium boilers and could be part of the problem.
    When it seizes (that may not be the best term for it) there is no flow. The sound changes and no water flows at all. I can get water and steam and through the wand no problems. I can recreate this problem every time I turn the machine on.

    We we don't generally leave the machine on for long periods of time. Just turn it on to make a few coffees and then off again. It's been a champ of a unit, 13 years old now. just gotta fix this strange issue and my romance with it can continue.

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  • JojoS
    replied
    Please be aware of the recommended duty cycle of the vibe pump at 1 minute on and 1 minute off. Do you backflush? If you can, do you get a good discharge and a pop from the 3 way solenoid? You should pop the top off and do an ocular inspection to check if anything is loose. Unplug the machine before you do.

    Leave a comment:


  • LeroyC
    replied
    Originally posted by timjeffries View Post
    From the moment the brew light turns on I can run the pump continuously. It never seizes, I just filled 4 cups. Once it's been running for a while though and I turn it off. When I turn it back on it seizes.
    When you say it 'seizes', do you mean there's no flow or a reduced flow? If it's no flow at all it's probably just an air lock and should be able to be rectified by running water through the steam wand to prime the pump. If it's a low flow problem then I'm not sure. It sounds like you leave the machine on for extended periods of time. This is not good for small machines with aluminium boilers and could be part of the problem.

    Leave a comment:


  • timjeffries
    replied
    Originally posted by LeroyC View Post
    Yeah do the water debit test to eliminate the pump first. There's full instructions on CG and GUG if you haven't found them already and it's easy to do.
    Thanks Leroy, will test out the pump later today.

    Leave a comment:


  • timjeffries
    replied
    Originally posted by JojoS View Post
    The spurts of water and steam from the steam wand only indicates that your boiler heats up properly. Can you make hot water without the pump seizing? How many ml. of hot water before it seizes?
    From the moment the brew light turns on I can run the pump continuously. It never seizes, I just filled 4 cups. Once it's been running for a while though and I turn it off. When I turn it back on it seizes.

    Leave a comment:


  • LeroyC
    replied
    Yeah do the water debit test to eliminate the pump first. There's full instructions on CG and GUG if you haven't found them already and it's easy to do.

    Leave a comment:


  • JojoS
    replied
    The spurts of water and steam from the steam wand only indicates that your boiler heats up properly. Can you make hot water without the pump seizing? How many ml. of hot water before it seizes?

    Leave a comment:

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