Gaggia D90 Restoration

Equipment doesn't work? Troubleshooting? If you're handy, members can help.
austensutherland

#1: Post by austensutherland »

Hey everyone,

I was able to pick up a used Gaggia D90 from the 90s for next to nothing and was hoping to use it to learn how to take apart a machine. The previous owner informed me that they hadn't used the machine in years, but last they had it was in working condition.

I've found some schematics of the machine online, but am having a hard time finding a manual for this specific model. Curious if anyone here has come across one that they wouldn't mind sharing with me?

I was also able to "plumb" the machine with my flojet and it turns on / heats water without issue. It is also able to distribute water from the hot water and steam nozzles which is a plus. I attempted to pull a shot just to see if the machine was capable, and it appears to build up some pressure, then spurts water out from the relief valve. A video recording with sound can be found here https://imgur.com/j9yLIvr (I wasn't able to attach a video to this post). I assume this means that there is some blockage, but would love guidance if anyone has seen this before / knows where I can get started.

Any help will be much appreciated!

Cheers,

Austen






nahau

#2: Post by nahau »

First off, I also can't find a manual for this machine, so no luck there. Secondly, I know nothing about Gaggia's, but...

You say the machine heats up fine so I have to assume the boiler pressure gauge responds accordingly? That is the boiler pressure gauge on the right side of the machine, correct? The reason I ask about the gauge is that in your video, the gauge indicates 0 bar. The place the water shoots out of appears to be an anti-vac valve the way they have sort of a bowl around the valve to seemingly catch a little water out of the valve until it closes when the boiler reaches enough pressure. If it is as it appears, then I'm guessing the valve is open as there is no pressure in the boiler indicated by the boiler pressure gauge. So... when you push the button, water just shoots out of that valve because it's open.


Never mind, I just saw a parts diagram on a different Gaggia D90 that indicates the squirting valve as a safety valve.

https://www.cafeparts.com/Espresso-Mach ... iler-level

JRising
Team HB

#3: Post by JRising »

In order for your pump to be over-pressuring the boiler like that (When it thinks it's brewing) means that your boiler-fill valve is stuck open. You can't test much else until you fix that issue.