Posted Mon Sep 20, 2010, 8:32pm Subject: Can a vibe pump lose pressure?
Starting this morning I can't seem to pull a decient shot. I am getting pull times of over one minute. At first I thought it was the grinder but I have been adjusting the grinder coarser yet the pull times are getting longer. I can put a blind basket in and turn on the brew switch and no water flows out the pressure regulator return line.
The water delivery out the steam wand doesn't look noticably off. Also with no portafilter the water flows out of the group sort of normal. It may be a bit slow but I did not measure it when the machine was healthy so I have no frame of reference. Sadly I haven't yet put together a pressure gauge.
I am thinking the pump is going South but I figured that when they die the flow would be way off.
Posted Tue Sep 21, 2010, 8:59am Subject: Re: Can a vibe pump lose pressure?
Does your machine have a solenoid valve? I mean, when you use the blind filter does it build up pressure and then when turn off the brew switch do you hear a "whoosh" as all that pressure empties out? If you don't have the solenoid valve, then the pressure would stay in the blind filter and make it very difficult to unlock the portafilter (does that happen?). Do you hear the pump get quieter as it comes under load using the blind filter?
Have you taken a look at your filter basket? Hold it up to the light, can you see through all the holes?
CupCak3 Senior Member Joined: 21 Jan 2010 Posts: 47 Location: OH Expertise: Just starting
Espresso: Isomac Relax Grinder: Vario
Posted Tue Sep 21, 2010, 9:35am Subject: Re: Can a vibe pump lose pressure?
You may have an issue with one of the ball checks in the pump. The pump is very easy and pretty intuitive to take apart if you have a little mechanical ability.
Posted Tue Sep 21, 2010, 9:50am Subject: Re: Can a vibe pump lose pressure?
Hi Andy,
Yes the machine has a solenoid valve. Good test. There is no "whoosh" sound when the three way valve dumps. Also the sound of the pump hardly changes with a blind basket in the portafilter as I open and close the steam valve.
This morning I pushed Miss Silvia aside and brought out my $39 Tonic. Using the same baskets in the portafilter and the normal settings on the Rocky my shot times are back to normal.
My audio memory is not all that reliable but I think the pump sounds different.
I will order a pump as well as a group head gasket, steam valve rebuild kit and burrs for the Rocky. It was time for those other parts.
When the pump arrives I'll verify that it is the problem but I'll leave the Tonic in place for a while. I have had my PID stuff for about five years so it's time for that as well.
With all the holes drilled for the PID I'll verify that it works then disassemble the machine, sandblast the frame and have it powder coated. It is getting to be something of a rust bucket.
Phil
AndyPanda Said:
Does your machine have a solenoid valve? I mean, when you use the blind filter does it build up pressure and then when turn off the brew switch do you hear a "whoosh" as all that pressure empties out? If you don't have the solenoid valve, then the pressure would stay in the blind filter and make it very difficult to unlock the portafilter (does that happen?). Do you hear the pump get quieter as it comes under load using the blind filter?
Have you taken a look at your filter basket? Hold it up to the light, can you see through all the holes?
Posted Tue Sep 21, 2010, 9:56am Subject: Re: Can a vibe pump lose pressure?
Thanks for that suggestion. I'll give it a shot. After all $50 does buy a decient amount of beans.
Phil
CupCak3 Said:
You may have an issue with one of the ball checks in the pump. The pump is very easy and pretty intuitive to take apart if you have a little mechanical ability.
Posted Sun Sep 26, 2010, 5:47pm Subject: Re: Can a vibe pump lose pressure?
The day after the failure I had to go out of town for work. I am back today and tomarrow so I will try to get to pulling the pump out and cleaning, inspecting, and dissasembling it if possible.
physicsdude Senior Member Joined: 18 Feb 2008 Posts: 41 Location: British Columbia Expertise: I love coffee
Espresso: Expobar Office Lever Grinder: Compak K3 Touch
Posted Sun Sep 26, 2010, 8:08pm Subject: Re: Can a vibe pump lose pressure?
There is at least one web page that has some detailed instructions on disassembly and cleaning of the Ulka vibe pump (one of the most common ones used). I used the instructions at Ulka Pump Repair Blog
Posted Mon Sep 27, 2010, 1:06am Subject: Re: Can a vibe pump lose pressure?
Thanks for the link. I looked at it then pulled the pump out of the machine. Being a lazy sort, I thought I'll dissasemble this pump if I have to but first I''ll run some vinegar through it and see what happens. I stuck the inlet tube into a bottle of white vinegar and pointed the outlet into the bottle I let it run for about a minute, then let the pump sit for about one half an hour. I repeated the vinegar thing. the pump started to sound different so I flushed it with water and put it back in the machine. Now with the blind filter if I turn on the brew switch water comes out the return tube. It is to late to drink a shot but all seems to be well.
When I wake up I expect to get a good shot out of it.
Thanks for the help.
Phil
physicsdude Said:
There is at least one web page that has some detailed instructions on disassembly and cleaning of the Ulka vibe pump (one of the most common ones used). I used the instructions at Ulka Pump Repair Blog
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