I just got my Laurentis single group machine all torn apart, cleaned up, put back together, and it is working great. I was using it off of a bucket for a few days while waiting for some plumbing parts with no issues.

I installed the plumbing with 3/8" compression, 3/8" NPT, or 3/8" OD pushfit plumbing everywhere. However I noticed that sometimes the pump makes a strange sort of squeaking noise. I suspect it is cavitating.

The plumbing to the machine goes like this:
1/2" copper line with sweatfit to 1/2" NPT fitting
1/2" NPT to 2X 3/8" compression shutoff valve (one line going to sink other to Laurentis)
3/8" shutoff valve
3/8" compression braided line
3/8" compression to 3/8" NPT adapter
3/8" NPT pressure regulator
3/8" NPT T to 1/4" NPT for pressure gauge
3/8" NPT to 3/8" OD pushfit
3/8" OD line (very short)
3/8" OD pushfit to 3/8" BSP
3/8" BSP braided line to machine

The bucket plumbing is as follows:
3/8" OD pushfit backflow preventer
3/8" OD line
3/8" OD pushfit to 3/8" BSP
3/8" BSP braided line to machine

Even If I max out the pressure regulator the pump will still cavitate despite the pressure gauge continuing to read ~60 PSI. There is no in home filtration upstream of this plumbing. I can't figure out why it works fine from a bucket but not a pressurized line especially since the supplied pressure doesn't seem to drop. Also it will still make this noise when using a backflush basket where there is no flow.

Any ideas or solutions?

Make sure all your valves are open all the way before the pressure regulator. Then set your pressure regulator to around 40psi and see if that works better. Cavitation tends to be a problem when the pump can't get enough water into it.

If that still doesn't help, post a video of what it sounds like. Sounds can be super helpful to know what is going on.

Edit: grammar

Did you adjust your pressure down after plumbing?

If it's set to 9 bar out of a bucket, it will be set much higher when plumbed. I'd set the line pressure to 30-40 psi and reset the pump pressure to 9 bar and see how it behaves...

**Edit**
Also monitor the pressure immediately in front of the pump and see if it drops while the pump is running. As mentioned above, cavitation is generally a supply issue. A dip in supply pressure would confirm that this is the case. If pressure stays strong, it's likely something else you're hearing.

When I was initially using it from the bucket it was set 9 bar brewing pressure. When I plumbed it in I adjusted it down so that it produced 9 bar with 22 PSI inlet pressure (listed as the max pressure on the side of the machine).

Here are some videos of the noise and then absence of the noise when running off the bucket.

The pressure in front of the pump does not seem to drop which is why it seems weird that it would be cavitation as the supply does not seem to be overly restrictive or limited. I am monitoring this pressure after the pressure regulator so it does not account for pressure drops across lines and connectors after that lead into the machine. These are however the same lines used when run off the bucket.

Edit:
I have also noticed that when I remove the cap to adjust the pressure on the pump there is some leaking. Once the cap is put back on the adjustment screw the leaking stops. I'm not sure if this is normal on these procon pumps or related to the noise I'm hearing.

This is odd indeed.

Does it cavitate when filling the boiler as well, or just When you activate the group? It's hard to make out the audio on my phone. Have you used a mechanic's stethoscope or similar device (long screw driver pressed to ear) to verify it's definitely coming from the pump?

The leaking pump is just the o ring on the pressure adjusting valve plunger. There is highlighted on an FOT pump in a recent topic. Should be virtually identical on the Procon.

Cheers!

- Jake

I have not gotten a chance to try the screwdriver trick as the pump noise is a bit intermittent. It will make the noise both when filling the boiler as well as feeding the group.

Perhaps it is a bearing noise? I'm not sure if it would be from the pump or the motor itself.

I was able to perform the screwdriver test while it was making the noise and its definitely seems to come from the pump. It sounds more like a squeaking seal or a bearing though than any sort of cavitation.

It may be worthwhile to pull the plungers out of the bypass valve and lube the seals up/replace the leaky o ring. The valve may be chattering when met with the back pressure of the supply line and less inclined to do so when drawing from a bucket.

Either way, you'll end up more familiar with the pump and you'll fix a known issue in the process.

How's the rest of the machine treating you with the Super Jolly feeding it?

Cheers!

- Jake

Thanks Jake, that seems like a reasonable explanation. I'll have to try and track down some replacement O-rings for the pump and pull that.

The machine and grinder are working great still working on my own skills on how to get the best shots out of them but I've been able to make some pretty good cappuccinos and lattes and what I would say are decent espresso shots. Might try and outfit the machine with a temperature sensor in the brew water path similar to erics thermometer for the E61.