When I clean my group head using a blind filter I run the pump for 10 seconds. When I turn it off and pressure is released I normally get a spurt of hot water from the nipple on the left side of the drain tray. Lately the pressure is not being released from the nipple. So when I loosen the portafilter the pressure is released there. Does anyone know the cause and fix for this?

I wonder if my group head needs a rebuild with new gaskets. What are the typical symptoms when a rebuild is necessary? Thanks for any comments you can offer.

If you let it sit, and don't remove the portafilter, does it eventually work? The 3-way valve has a maximum operating pressure, if exceeded, the pressure against the valve-face is high enough to hold the valve against it's normal position. If after sitting for 30 seconds, the pressure may have dropped off enough to let the valve shift back to normally open on the drain side and it should relieve.

Try this. Do the blind disk back-flush motions, but only let it pressurize for 2 or 3 seconds, and if the three way is working normally at lower pressure, check why the brew pressure is too high, probably needing adjustment at the pump's bypass valve.

If the three way valve doesn't relieve properly, even at low pressure, either the valve or the tubing down to the tray might be completely clogged, or the spring on the valve's nucleus could be broken.

Thx JRising. My pump pressure shows about 8.6 bars when there's coffee in the portafilter and I'm pulling a shot. I turned it down from 9 bars. Tomorrow I'll test letting it sit 30sec. I've spent quite a bit of time over the last 2 weeks trying to get it to clear. That includes turning it on then off immediately multiple times and on for a few seconds then off, when using a blind filter. I even removed the nipple and cleaned it. There was a bit of residue around the opening, but nothing inside the nozzle. Is the 3-way valve at the opposite end of the tube from the nipple? I could probably remove it and clean it as a next step.

Do you have an MP or an AV?

I have the MP.

Ok. There is no 3-way valve on your machine. Everything is internal to the group. Does your gauge turn with the paddle (conical valve) or raise up and down like a periscope (pre-conical)? Either way, your group will likely need service, but there is a slim chance you could get away with a series of detergent back flushes if it is an issue of some sort of buildup of scale or gunk.

It it is the older periscope style, chances you have a torn O-ring blocking the discharge port in the group. The O-ring kit is reasonably priced, but you'll need the extraction tool, as well, which is not exactly free.

If you have the conical valve, there is a better chance of it just being some sort of buildup you can clean out with detergent, but pulling the group cap (which requires an O-ring kit, as the lower O-ring will almost certainly become torn in the process of disassembly) and servicing the valve is still recommended.

Cheers!

- Jake

There's a shower head at the exhaust port on the left side of the drip tray, just like the one on the hot water wand. It can get gunked up and require periodic cleaning. It's a little tricky to remove (I think I used water pump pliers with a rag to protect the finish), but a good place to start as it's much less invasive than dismantling the group!

Remove the left side panel to get a clearer view of the part. This will be helpful/necessary for the reinstall.
Also, if it turns out to be scale, check your water chemistry!

Splunge wrote:There's a shower head at the exhaust port on the left side of the drip tray, just like the one on the hot water wand. It can get gunked up and require periodic cleaning. It's a little tricky to remove (I think I used water pump pliers with a rag to protect the finish), but a good place to start as it's much less invasive than dismantling the group!

Good advice.
Per the OP's response to John below, I figured this was already ruled out, but you are certainly correct that this is easier than digging into the group!

tomasso wrote:I've spent quite a bit of time over the last 2 weeks trying to get it to clear. That includes turning it on then off immediately multiple times and on for a few seconds then off, when using a blind filter. I even removed the nipple and cleaned it. There was a bit of residue around the opening, but nothing inside the nozzle. Is the 3-way valve at the opposite end of the tube from the nipple?

Oops my bad. I should read threads thoroughly before I post!

It would probably still be a good idea (if it hasn't been done already) to make sure there's no flow with a blind basket and the aerator removed. Mine looked fairly clean on the outside but was completely blocked internally.