Intermittent no pressure at group head

[Glen]

Hi, I have an S1 and I’ve recently noticed that randomly it takes maybe 8 seconds to get pressure at the group head. The pressure / pump works fine 90% of the time. I’ve checked the check valve and water tank and all seems ok. I can hear the pump run but the pressure to the group head is delayed and this ruins the shot.

[chas]

I show the water flow inside the Mini in the diagram below. I labelled a part "expansion valve" in this diagram but that is because that is what the same part is used for in the plumbed-in version. However, in the Mini, it is used to adjust group pressure. You're not the first one to post with this problem. I normally suspect this part since it is just a rubber piece on the end of a spring that blocks a hole which lets water through. However, to a man, all the others have found that the pump itself is the culprit.

You may still want to dissasemble this valve to check for a partial clog since doing that is free. However, the pumps are not too expensive, if it should come to that.

Mini-Water-Flow.jpg (37 KiB) Viewed 4091 times

[Glen]

Hi, thanks for the response. Are you referring to the over pressure valve that sits just below the vibe pump on the diagram?
Many Thanks
Glen

[chas]

yes

[chas]

Were you able to fit the problem?

[Glen]

I’m planning to start the repair next week. I’ll keep you posted