Machine is leaking water during operation...does it need new O-ring???

I just fixed a similar problem with my Delonghi Eco 310. Halfway through making a cup water stopped coming out but ran out from underneath.

This is how i fixed it:

First I checked the little tube that goes from the pump and anti drip valve into the boiler unit. There is a clamp on both ends to remove before you can take it out. First fault can occur here, check the black little O-Rings that might still stuck inside the connectors, if they are worn out they might need replacing.
Then check the little tube for any damage, even any fine tiny cracks can lead to a big leak as 15 bar go through it.
In my case there was no damage there, also not on the tubes that come from the watertank into the pump.

After I checked all that and it seemed fine, I turned the machine back on again with open top (careful of any electrical contacts!!!). Then I saw that water and steam came out of the anti drip valve. It seemed the water got sucked into the pump, pumped into the boiler, heated up there and put to 15 bar, but because the valve was broken the water didnt actually came out but searched the easiest way, which was the broken valve, that regulates the pressure. I went on a site for delonghi spare parts, bought a new valve for £5, replaced the old one and -tadaaaa! It works again!

Just above the pump there is a check valve that may be stuck open
during operation which will cause thin ice. Also make sure you have the o-ring on the bottom of the drain tube if it was removed during cleaning.

Thanks for the quick responses.Pulled front cover,ran a load on high level, no leaks .Ran a load on super level and when drum spins when full of water water level rose and poured out of left front side on top of drum. Pulled plastic ring on top of drum and and found piece of seal missing where leak occured .Ordered upper tub seal, should solve problem

Most likely it starts the espresso but stops after a few second because the unit is not getting the water flow information or the unit is blocked. You will know that you have a blockage because not water will come out of the espresso filter but most likely you get some liquid during the 4-10 seconds it operates. My unit has the same problem and I fixed by getting a new flow meter. This unit is installed after the water tank and has wires (3) going to the the power module.

Hi
If your water valve is cream or black colored, you need a new manifold. They will get hair line cracks if you steam, but don't cool them down after steaming by running cold water through them. If you have one of the new brass(silver) manifolds it could be your O-rings but i doubt it.

Replaced water pump, found 2 quarters located within the old water pump which destroyed the o-ring causing a small leak and hindered the operation of the entire machine.

I rang Saeco service centre about my leaking water tank and they posted me a new tank - no questions or need to return the faulty item. I believe there may be a bad batch of tanks which leak because of faulty valves.

You must examine your machine hose to see if it is blocked. Clean out the fine nets in the hose as well as at the machine entry (inlet water entry). Clean well with a tooth brush, refit carefully. Water should be in good pressure for machine operation.

Bosch Nexxt 500 WFMC3301 Front Load Washer how
to get the metal ring back on.
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the highest water fill cycle for your waher is the clean cycle.it will fill up with 2x the normal amount of water in this cycle than any other.look for a cut or wrinkle in your door boot(grey rubber outer ring that seals between door and boot)if you find one,only fix would be to replace door boot.also clean inner door glass that comes in contact with door boot ring,any hard water build up or sediment(dog,cat or human hair)will break the seal and allow it to leak.good luck