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Gaggia Classic OPV
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CRW
Senior Member


Joined: 24 May 2012
Posts: 41
Location: PA
Expertise: I love coffee

Posted Fri May 17, 2013, 2:30pm
Subject: Gaggia Classic OPV
 

Re: my Gaggia Classic---I don't have a portafilter pressure gauge because with my older style portafilter (2 solid spouts, not a threaded-in double-spout) there's no way to attach a gauge. I tried using a blind filter and measuring the back-flow thru the OPV, into a measuring cup. At the point where I was getting a flow rate close to what was shown on the pump flow chart, I found that the OPV was too loose to contain the steam pressure once I switched to steam. Around the same time that the ready light would come on, the hot steam and water would eject thru the OPV, back into the tank (or cup, once I started measuring that particular event. It was approx 50 ml.) I have no idea what the actual pressure setting is at this point. I don't know what it was when I bought the machine used. I've had it all apart before, descaled, etc., so it's not possible to do "2 turns from the factory setting" or whatever. I was hoping that measuring the flow would work because I've read on various forums where people have had success with that method. Has anyone else had trouble with water releasing thru the OPV while making steam? Or know what pressure it would take for that to happen? I ended up just retightening the OPV little by little until the steam wasn't releasing anymore. But water also never releases during a shot either.
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D4F
Senior Member


Joined: 15 Mar 2012
Posts: 2,015
Location: USA
Expertise: I like coffee

Espresso: Gaggia Classic PID
Grinder: Baratza Forte-AP
Posted Fri May 17, 2013, 8:23pm
Subject: Re: Gaggia Classic OPV
 

Without a boiler thermometer the steam temperature is not known for sure, but assuming that the steam stat works you could get in the 280F - 300F range and that could generate about 3+ bar pressure.

"Steam can build up 3+ bar of pressure at about 280 - 300F.  If steam caused OPV push back, you are way too loose."  from your prior thread.
Click Here (www.jgbhose.com)

My OPV needed about 3/4 turn lose from factory.  Your machine is about 10+ years old IIRC.  The OPV could need to be removed and cleaned or replaced.  From your description it is not just set too low as if you try to tighten, then you get no flow back with a blind.

Try this assuming that your Classic has copper tube from steam valve out.  That is standard but I am not sure on vintage.  Probably always the same.

http://www.youtube.com/watch?v=Csyu1qg5BXs

 
D4F also at
http://www.gaggiausersgroup.com/
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CRW
Senior Member


Joined: 24 May 2012
Posts: 41
Location: PA
Expertise: I love coffee

Posted Fri May 17, 2013, 9:15pm
Subject: Re: Gaggia Classic OPV
 

I tried measuring the pressure with a similar set-up a few months ago. Even with the OPV cranked down all the way, I couldn't get it to read the pressure correctly; it was way low. But, at the same time, my steam valve is pretty leaky and some of the pressure leaks from that during the test. I've had the OPV all apart, and I soaked the pieces in citric acid to descale. They are very clean and fit together easily. The valve is so simple I can't see how it could go bad if was cleaned and not stuck or gunked up with scale. I guess I can only be sure of the pressure at the group with a portafilter gauge. I just don't have the $$ to buy a whole new portafilter at this time.
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D4F
Senior Member


Joined: 15 Mar 2012
Posts: 2,015
Location: USA
Expertise: I like coffee

Espresso: Gaggia Classic PID
Grinder: Baratza Forte-AP
Posted Fri May 17, 2013, 9:38pm
Subject: Re: Gaggia Classic OPV
 

Didn't you have a possible pump problem?  Seems like it is possible that you have a low pressure failing pump based on what I recall of prior posts.  If so, then setting the OPV down would allow the pump to over pressure at steam pressure.  Tightening the OPV could shut off the steam backflow and the pump against blind if the OPV is working normally.  OTOH, if the OPV is failing then the pump and steam may flow back because the OPV is set very low and then instead of modulating it is more of on/off.  You still have too many variables.

Agree that PF is too expensive just to get for pressure.  What leaks with the fitting attached to the wand?

Next pressure try

Click Here (www.home-barista.com)

Plug one PF hole with short piece of dowel or similar cork, and try this in the other hole.

If you do not bike or have a ruined tube, try a bike repair shop for an old throw out tube for the stem.

 
D4F also at
http://www.gaggiausersgroup.com/
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D4F
Senior Member


Joined: 15 Mar 2012
Posts: 2,015
Location: USA
Expertise: I like coffee

Espresso: Gaggia Classic PID
Grinder: Baratza Forte-AP
Posted Fri May 17, 2013, 9:46pm
Subject: Re: Gaggia Classic OPV
 

On the OPV, couldn't the inside spring fail with time and use?

http://www.ruizs.org/archives/46

You could make a gauge fit a blind with a hole drilled and JB weld.  Lower on the page above.  He welded, I used JB weld here for similar seal.

http://coffeegeek.com/forums/espresso/machinemods/588424

 
D4F also at
http://www.gaggiausersgroup.com/
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D4F
Senior Member


Joined: 15 Mar 2012
Posts: 2,015
Location: USA
Expertise: I like coffee

Espresso: Gaggia Classic PID
Grinder: Baratza Forte-AP
Posted Fri May 17, 2013, 9:57pm
Subject: Re: Gaggia Classic OPV
 

Sorry to fragment this stuff, but searching and recalling as I go.  Inexpensive and decent double baskets, and blind.

Click Here (www.espressoparts.com)

http://www.espressoparts.com/EPF_156?&search_id=2079804

I used this and JB welded the holes and put in a tube.  Similar would make a basket for a gauge. Also decent baskets to use for brewing and PARTSSHIPFREE, see site reference.

 
D4F also at
http://www.gaggiausersgroup.com/
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CRW
Senior Member


Joined: 24 May 2012
Posts: 41
Location: PA
Expertise: I love coffee

Posted Sat May 18, 2013, 8:07am
Subject: Re: Gaggia Classic OPV
 

thanx for the links, I'll take some time and check those out, as well as other options to make a gauge with the existing portafilter. I already have the gauge itself and some of the brass fittings.  I agree I'm still working with a lot of variables. Before when I was writing about this, I did suspect pump problems, but after extensive descaling and unclogging some build-up in on of the pump fittings, as well as doing a water debit test as shown on the Yahoo Gaggia Users Group, I think my pump is OK. The problem with the steam releasing was amplified when I recently replaced my steam t-stat, as the old one seemed to be cutting out early.
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CRW
Senior Member


Joined: 24 May 2012
Posts: 41
Location: PA
Expertise: I love coffee

Posted Sat May 18, 2013, 8:12am
Subject: Re: Gaggia Classic OPV
 

also re: the steam valve leaking--it's something in the valve itself. When I run hot water out of the steam wand, it drips like crazy around the valve, inside the box. When the machine is sitting idle with the valve closed, water still drips from the wand, into a cup. I get pretty good steam from the wand to make frothed milk. But when I attach a hose and gauge directly to the wand to test pressure as in the youtube clip, so much water is leaking from the valve I'm sure I'm not getting a good measurement.
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D4F
Senior Member


Joined: 15 Mar 2012
Posts: 2,015
Location: USA
Expertise: I like coffee

Espresso: Gaggia Classic PID
Grinder: Baratza Forte-AP
Posted Sat May 18, 2013, 9:30am
Subject: Re: Gaggia Classic OPV
 

Leak back along the threads of the needle, or from the valve into the tank.  You may be interested in this thread.

http://coffeegeek.com/forums/espresso/machinemods/607264

 
D4F also at
http://www.gaggiausersgroup.com/
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CRW
Senior Member


Joined: 24 May 2012
Posts: 41
Location: PA
Expertise: I love coffee

Posted Sat May 18, 2013, 10:52am
Subject: Re: Gaggia Classic OPV
 

When the valve is open it leaks out around the handle, into the enclosure. When the valve is closed, drops of water or steam leak out of the wand. I read that thread before. Never tried the mod to take the valve apart, I'm a little squeamish about cutting it apart. But maybe I'll do it if I get sick enough of the leaking. The thing is, according to the Gaggia Users Group info, the fix is sort of temporary, the leaks always return, and even after replacing the valve, leaking is inevitable....
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