I have a Rancilio L4 1 group manual espresso machine.
The pressure/temperature is set too high, resulting in espresso of poor flavour and little crema.

The associated grinder is a Rancilio Rocky doserless in good condition. Recently pulled down, cleaned, burrs checked and recalibrated.
Coffee used is a good quality and roasted in last 3 weeks (and has all the great characteristics when extracted on another commercial machine).

I have a portafilter with a pressure gauge to calibrate the machine. I just don't know what I need to do to adjust the pressure/temperature.
I have searched the internet for some hints, but this "antique" doesn't rate a mention.

Anyone have any resources or knowledge that could help out?

Normally, I'd try and find a local repair shop - but it's on the 4th floor of a stairs only building and it weights a ton!

Correct me if I'm wrong, but L4 temp. is regulated via pressurestat ( grey box inside machine with copper pipe leading to the boiler) adjustment screw on top with markings +and- to regulate pressure argo, temperature.
Hope it helps.

hardergm, what is your flushing routine for your L4? I ask because I have a similar S27, which uses a totally different routine than what is normally described for an HX machine.

Cyclery,
Not quite sure what you mean? Do you mean just before inserting the portafilla into the group head?
Or do you mean the end of day cleaning procedure?

If it's the former, and say the 2nd cup of coffee to be made, I'd remove the portafilla, flush the group head to remove any residual coffee from the shower screen, bang out the previous plug/cake of coffee from the protafilla, wipe out the portafilla to make sure it was clean and dry. After grinding the coffee directly into the portafilla, tamp it down. Before inserting the portafilla into the group head, I'd flush it again to make sure the water in the head was not over heated, insert the portafilla into the group head so it was firm and sealed and immediately start pulling the coffee

Is that what you meant?

Kind Regards
Geoff

Geoff,
Its flushing the overheated water just before pulling your shot that I was referring to. On my machine, I only flush around 2 oz of water. Most of the advice for HX machines describes long flushes, where the water slowly sputters to a steady stream. On my S27, it comes out in a gush lasting maybe 2 seconds before reaching proper temp. When I initially tried long flushes, I got really sour shots before I found a few references to managing "dragon" HX machines.

Re adjusting the pressurestat adjustment, I set mine so the outside of the boiler is around 238F. I have a cheap thermocouple wire clamped to the boiler, with a digital thermometer (old PID unit from previous Gaggia machine) attached to the outside of the machine. With the 2 oz flush, that gives me a fairly reliable 200F flow at the group head.

Re the pressurestat itself, my machine is a 1985 model. I was constantly adjusting the pressurestat to get usable temperatures before I threw in the towel and bought a new one. Wow. The new pressurestat is very consistent for temps and consequently the espresso flavor is consistent as well. I'm pretty sure that the diaphragm inside the pressurestat had lost its pliability after 30+ years and stopped doing its job. It was giving wide temp swings of plus or minus 5 degrees. One day the shots would be sour, the next day they'd be bitter, and so on. The new pressurestat is spot on every time, and the shots are generally tasty.

You might also think about preinfusion. Its easily accomplished with a delay-on-make relay, and really helps eliminate channeling on rotary pump machines.

Cheers,
David

Hi David

Your description really fits what's happening. It really acts like a "fire breathing dragon".

This is the 2nd L4 I've owned. The first was well behaved and pulled consistent shots with great crema. On this machine, the body work was a little knocked around and showed it's previous life. When this current machine came up for sale, it appeared to be in great condition and so I gifted the original machine. I had the new one serviced (by an allegedly reputable company) and its never been anywhere as good as the original machine.

I think I'll try and get access to my original machine with the pressure tester and take note of the readings. Then try and replicate that on my existing machine using the info from Coffee Cat in this thread.

If unsuccessful, your thought that the pressuresat is probably past its use-by date is probably correct.
If that's the case, it's probably hernia time lugging it down (and later up the 4 stories of stairs) unless I can find someone to do an on-site visit

Then you have to think is it worth persisting with this antique - or are you throwing good money after bad?

Thanks for your input

Cheers
Geoff

coffee cat wrote:Correct me if I'm wrong, but L4 temp. is regulated via pressurestat ( grey box inside machine with copper pipe leading to the boiler) adjustment screw on top with markings +and- to regulate pressure argo, temperature.
Hope it helps.

Hi Coffee Cat

I've located the grey box with the screw on top and copper pipe coming from the bottom.
There are no markings near the screw to indicate the direction of turn to increase or reduce the pressure.
Before I start a trial and error process, would you happen to know if counter-clockwise (which would seem logical to me) is to reduce pressure

Thanks

Geoff

The P-stat has a screw which can be used to adjust boiler pressure. If your L4 doesn't have a gauge to give a pressure reading, you can rig one to the steam wand for adjustment purposes.

The portafilter pressure gauges can be used to adjust pressure at the group during flow, by adjusting the screw on a rotary pump as the pump delivers water to the group.( or adjusting an over pressure valve of a vibratory pump.)

Hi Flint

Thank you for your input.

By any chance would know of the optimum pressure settings for the boiler and at the group head?

Cheers
Geoff

The counter clock is to reduce the pressure, give it a quarter of a turn and see what happens. To make sure its working, listen to it while the lid of machine is removed, ( do not remove pressurestat cover!) it should click when on and off, cycling. I adjust my temperature, by measuring it with thermometer about 202f. is my preference.Pressure gage is not very accurate instrument and I use it only as a general indicator.