Hi,

I've got a La Nuova Era Cuadra from 2011 with an E61 grouphead which seems to have started leaking water during the brewing process. This leaking also occurs when backflushing with a blank in.

After a month or so of putting up with it I went ahead and bought the rebuild kit from Stefano's Espresso Care and changed all the gaskets out following Randy's awesome guide on his FRCN website. When rebuilding the grouphead everything was nice and clean with virtually no scale (we are blessed with great water in the SF Bay Area). Unfortunately this didn't seem to fix the issue and I'm still getting a similar amount of leakage from the exhaust port.

I'm concerned that the leaking water may be limiting pressure or flow at the brewhead. Any thoughts on what I might look at next to solve the issue? Could it be that the exhaust/drain valve spring needs to be replaced?


Thanks!

Thanks for the kind words!

If the metal portions of the valves' stems were worn then it would have the potential for leaking less. I would have you check:

• * The "exhaust" (3-way) valve's seat (where the rubber seal sits inside the group to create a seal) for damaged or corrosion. You would see this looking up into the bottom end of the "infusion body" seen in step 8 of my guide.
  * That the brew pressure is correct when backflushing (this is a stretch because I think the water pressure required to open that valve would be very high)
  * Possibly the spring for that valve is weakened and needs replacing. You might be able to test this by placing a washer at one end of the spring or the other to increase the closing force.
  * The exhaust valve's retaining piece at the bottom is completely screwed in

If it helps, my own experience and tests of many machines have shown the pressure required to open the lower exhaust port valve can be from 13 -14 bar, depending on spring pressure. it's not usually higher, or lower. Low pressure release of this usually means a worn seal on the bottom exhaust valve. If you have rebuilt with replacement components, no all groups/valves are dimensionally the same and this can also cause a leak as the valve doesn't close properly.

If it is a dimensional problem, then the long pin (the one that presses open the exhaust valve) on the preinfusion valve can be ground down a tiny bit until it stops leaking.

DaveC,
Good call on possibility of incorrect (too long) valve parts. I thought about that, but he did mention that it was happening before and after the overhaul. Maybe he got the machine used from someone who used the incorrect parts? WOuldn't be the first time something like that happened, regardless as to whomever previously worked on the machine.

Sure, I was thinking it's likely he may have exchanged 1 problem for another that looks similar, assuming he purchased a new set of valves and didn't replace just the rubber seals. so the old valve leaked and the new sit might have that longer pin. Trouble is there are a number of E61 clone manufacturers in Italy and the parts are not exactly universal (small variances). The machine companies that buy these groups can change also supplier without saying anything. It's all a bit of a pain. The only parts almost guaranteed to fit are those from the company that makes the group.

Even worse, some manufacturers cast the groups only and then buy generic internal parts from suppliers....you can imagine the mess that makes when suppliers change or their spec changes!

Hi Guys,

Thanks for the recommendations on things to look at.

I did buy the machine used about a year ago, but I'm pretty sure the leaking has not been present for the entire time I've owned it. When I took the group apart I only replaced gaskets and not the valves themselves.

This morning I confirmed that the leaking is present during backflushing. The machine still generates significant pressure and has a large "blowoff" when the brew lever is switch to the down/off position.

Another thing worth noting: after doing the rebuild and observing the continued leaking, I also thought it could be an issue with the length of the preinfusion valve being long enough to interact with the cam while the lever is in the "brew" position. I took the brew lever apart to expose the cam pocket and moved the lever on/off triggering the pump and couldn't immediately see any adverse interaction with the preinfusion valve while the lever was in the "brew" position.

When I've got some more time I'll probably take the exhaust portion of the group off again and inspect the valve seats and try shimming the springs per Randy's suggestion. Do you guys think it's more likely an issue with the longer preinfusion valve/spring or the shorter exhaust valve/spring?

As Dave noted, it takes an increase of about 50% over normal brew pressure to open the exhaust valve.
If you are sure that it did not leak previously then my guess is that either the spring is weak of the seat is damaged.

If the inspection does not reveal any new evidence here is another possible test: To eliminate the possibility of the infusion valve being too long you could remove it, reassemble the group with the exhaust valve in place, and do another blind-filter backflush. Be aware that there will still be some pressure remaining in the group when the lever is returned to the down, "off" position at the conclusion of the test, so use care when removing the portafilter.

Just to update you guys, I removed the infusion valve to test if the it was too long and interfering with the cam. With a blank basket in, I still got leaking. I next tried shimming the exhaust valve with a 1.75mm thick washer I found lying around. This seemed to stop the leaking during backflushing. After warming the machine up and pulling a shot, there is no longer any leaking during the brew process and the group seems to be behaving as normal.

I have a strong suspicion that the weak spring was effecting the quality of my espresso by reducing the pressure at the basket and the volume of water flowing through the puck.