I have a Marzocco gs3 and it seems to be adding very small traces of oil to the water. I will try and upload a picture shortly, but if I run the machine with no basket straight into a cup I have a thin layer of oil on top of the water. Making an espresso the oil clumps together to form what looks like bubbles in the crema, but they are not. Does anyone know what maybe causing it, or how I could go about working it out? I have gone through the cleaning cycle with the blind basket and it has made no difference.

Tell us a little of how it started? Is it a new machine, did the symptom start one day, was it always like that? Also, when you ran the self clean cycle - did you use Cafiza or other coffee detergent?

Just a hunch - maybe some silicon (food safe) on the portafilter gasket (it makes the gasket easier to replace).

For what it's worth, I had a similar problem with my Oscar when I only did water backflushes. Now I use a cleaner called PuroCaff from EspressoParts and the oil is gone! It's likely coffee oils/residue. If it's not that, it could be lubrication from something within the group.

The machine is in an office and is typically used by people who don't really know what they are doing. This does cause a problem with keeping it clean and running without issue. I keep it clean, adjust the grind daily on the Mazzer and try make sure people clean the milk wand! Servicing for the GS3 is done by some one from a local coffee shop and is not something I look after.

The machine is about two years old, I noticed the symptoms about two weeks ago and it was fine before then. I have not yet tried cleaning the dispersion filter but that maybe my next step. I have been using Urnex Espresso machine cleaner.

I am stumped. I guess I'd try cleaning the gasket, the dispersion filter, replenishing all the boilers (from the expansion valve and steam boiler ball valve). I'd use quite a bit of cleaner after replenishing the water in the boilers.

Also - Could it be the water supply? Or perhaps an oily water filtration? Was it serviced before the oily substance appeared?

Not to ask the obvious, but does the cleaning include breaking down the portafilter, soaking it, scrubbing the grouphead gasket, and removing the dispersion screen? Because I've visited some cafes who were surprised to learn that the basket could be removed; this is what lurked below it:


From Espresso Machine Cleaning - Why, How, and When

Based on what you describe, I would bet on rancid oils being left behind by iffy cleaning practices.

HB wrote:I've visited some cafes who were surprised to learn that the basket could be removed; this is what lurked below it:

The difference in those portafilters... and the fact some cafe's look like that... *shivers*

Yup I have cleaned the basket and porta filters. Importantly it produces the same oily water with nothing attached to the grouphead. I took the dispersion screen off and gave it a good clean but it hasn't changed anything. I will get these pictures uploaded.