Recently, my Rocket Espresso Giotto Professional has started to "leak" from the exhaust valve during brewing and back flush. Not surprisingly, the back pressure at the end of the back flush has also decreased.

This morning, I searched the forum and removed the exhaust portion of the 3-way value and wiped it clean, which decreased the leakage but didn't completely cure the problem. The springs seemed fined, the parts a bit blackened but no scale present. I haven't checked the pre-infusion valve for wear nor opened up the lever to check the cam.

Can anyone offer any guidance on what to check next?

Do you have any pics? I'm not sure what the exhaust valve is.

I have the Celini and I lost backpressure when I de-scaled the machine and unhooked the water level probe, causing the hot water tank to get too 'full'.

when was the last time that you de-scaled? Also i would give the cam a look.

For more detail on the E-61 group, see these two articles on my website:
How-To 18 - Simple Lubrication of the E-61 Group
How-To 19 - Overhauling and Lubricating the E-61 Group
Sounds like you need to replace the valve seals.

Thank you for your suggestions and links.

I took the lower exhaust valve off and checked the valve seal. Please see the images below.





It looks like the seal has given all it has and needs to be replaced. Can one generally order only the seal or do you replace the entire brass valve? Also can you verify that this is the likely cause of the exhaust leak, even though it makes perfect sense to me.

Randy, when you have a free moment, please see my post below.

Here is my suggestion . . . order about 6 of the seals and ALL THREE of the valves from the dealer from whom you purchased the machine or just simply order all of these parts from Chris' Coffee or Stefano at EspressoCare and a small quantity of Dow 111.

In the links that Randy provided, he shows how to replace the seals themselves BUT, more often than not, you will either find that the part of the valve that contacts the cam is worn or you will break the threaded portion in getting to the seal. So, replace all of the valves and practice on the old parts.

Shipping charges are a "killer" when you want one seal.

I agree with Eric after looking at those photos. The odds of getting the valves apart is slim. But the valves' seals are shot, and it looks like they have been for some time. That group definitely needs to be overhauled.

Put the valves in boiling water for a while, then while holding the main body, use poliers to wiggle the end above the valve seal back and forth JUST A LITTLE to break it loose, and then try to unscrew it. They may come apart properly , but I would bet on what Eric said- they likely will break and need replacing anyway.

I am on dailup for the weekend and so don't wait for responses to come too quickly. It took a while for your images to download!

Thank you both for your help. I will order the parts.

For others reading this post, I received a Rocket Espresso schematic for the Giotto. I'd more than happy to post but it is very large and is a pdf.

Send it to my email address below my sig and I will fix it.