Posted Fri Sep 5, 2003, 9:31am Subject: La San Marco - Heat seized fitting
I have embarked on the rebuild of my La San Marco 85-16M. Things are going well and the machine is generally in good shape. However, there is a fitting on the boiler that seems to be heat seized. There is a flange that screws into the heat exchanger that I must get out in order to replace the heat exchanger gaskets, but no amount of brute force seems capable of breaking it free. The top flange did not have the indicated teflon gasket, so I assume that the bottom doesn't have a gasket either and that is why the flange is seized.
Anyone have any suggestions how to break it loose? I have heard of people using a torch to work on tough threaded fittings, but I haven't done this myself. Do you heat it while you have the wrench on it, or is it some sort of heating and cooling cycle.
A diagram of the connection is here. The problem part is the flange that passes through the lower group head circulation tube and screws into the bottom of the heat exchanger itself. It also has a small hole in the center for the fill tube. When I try to turn the flange the heat exchanger turns. I can hold the heat exchanger with a huge channel lock (not the best tool, but it works), but I simply can't break it loose.
koffeekev Senior Member Joined: 21 Jul 2002 Posts: 693 Location: Connecticut Expertise: Professional
Posted Fri Sep 5, 2003, 4:44pm Subject: Re: La San Marco - Heat seized fitting
I would be inclined to load the machine in my car and bring it to a boiler shop. There has to be someone around where you live that repairs or builds commercial boilers whether it be for heating or hot water. If you can't find this type of company try a good plumbing outfit. They usually have the tools needed. Good luck.
Posted Sat Sep 6, 2003, 7:14am Subject: Re: La San Marco - Heat seized fitting
Kevin - Thanks for the suggestions. As usual your assistance is very much appreciated, and I'm really glad you encourage me to undertake rebuilding the machine myself, instead of taking it to the shop. It's been interesting, enjoyable, and a great learning experience. It's actually been pretty relaxing to me for some reason.
I got the fitting loose and the boiler and heat exchanger are fine. However my not-so-elegant solution involved a hack saw and a credit card.
I very carefully hack sawed the flange off. All said about $43 in parts (new flange and lower group head circulation tube). Believe it or not, it was a calculated approach. I didn't feel comfortable taking it to a shop where they may keep it for days/weeks and end up breaking the boiler anyway. So I called to find out the price and availability of the parts and decided to take drastic measures. I put multiple layers of duct tape around the fitting at the boiler to keep from scratching the boiler up, and I hack sawed the head off of the flange. Not pretty, but effective.
I needed the new lower group head circulation tube anyway ($30) because someone crimped the tube a bit. It probably would have worked fine, but as long as I have it apart I may as well fix these things.
So my San Marco is stripped down to the the frame and I get all the parts to put it back together today. The boiler, heat exchanger, and all the little tubes and valves get Scale Kleen soaked, and if I'm lucky I'll be pulling shots by Monday. I'll let you know how it goes.
koffeekev Senior Member Joined: 21 Jul 2002 Posts: 693 Location: Connecticut Expertise: Professional
Posted Wed Sep 10, 2003, 4:23am Subject: Re: La San Marco - Heat seized fitting
When you get into a little trouble like this it's difficult for me to steer you in a particular direction. I have to try and visualize the problem and remember what your level of mechanical ability may be, if I know at all. I really wouldn't want anyone to get so deep that the project ends up being a box of refuse so I always recommend getting a second or third pair of eyes on a problem just as I do.
I try to find all the local hardware stores in my area because these people will go the extra mile when you really need help being creative. One New Years eve many years ago a store owner in Bridgeport, CT sliced a 3/8 inch compression nut with a hack saw to provide me with a special nut needed for a repair of a Bunn brewer. He charged me .35 cents for the trouble. It was cold and I was far from home so I will never forget this act of kindness.
We have three highly qualified technicians in the service department so it's only natural to ask for advice before jumping in to a disaster. We all get in trouble from time to time so I just want to be able to give the best advice I can.
When you refer to this being relaxing I am certainly on the same page. For years I always had one project or another on my basement bench waiting for my attention. I would come home from a long day, turn on the radio, pop a beer and "have at it". I often thought that if I could only find a way to make money doing this I would be a happy man. I did. I am. Kevin
Posted Mon Sep 15, 2003, 11:37am Subject: Re: La San Marco - Heat seized fitting
Koffeekev, you're alright! I've generally got such a project going on, and it's not as much relaxing, as it is the escape into pure mechanics, and engineering. This is a needed escape for me, as I'm currently doing software tech support rather than being service agent chad.
I've fully restored 4 commercial espresso machines of my very own. It's a quirky but awsome hobby. Just wanted to say that YouDaMan...
Posted Tue Sep 16, 2003, 10:53am Subject: Re: La San Marco - Heat seized fitting
thechadzone -
I've generally got such a project going on, and it's not as much relaxing, as it is the escape into pure mechanics, and engineering. This is a needed escape for me, as I'm currently doing software tech support rather than being service agent chad.
I understand this completely. I am a network administrator, and I used to mess with computers at home for fun, but it's just not fun anymore. I've noticed that I have a better day at work when I have my tool bag out, building a server rack, installing switches and routers, etc. instead of beating my head against some configuration problem or malfunctioning server.
I guess I've always been a tinkerer. Maybe you and I are both in the wrong line of work.
The La San Marco has been simple and well laid out machine. It's nice to look at something and be able to understand and appreciate how it works, this is not always true of computer work.
By the way the La San Marco is done, and the results were excellent. It used to have a problem with pressure and temperature at the grouphead, neither of those are a problem now. No steam leaks, no water leaks. Best of all, it pulls a pretty nice shot.
The only remaining annoyance is that the pump seems a little loud when filling the boiler, but not when pushing water through the grouphead. I assume that there is less resistance when filling the boiler, so I'm not sure if that has anything to do with it or not. Any suggestions on this last issue are appreciated.
Posted Tue Sep 16, 2003, 2:06pm Subject: Re: La San Marco - Heat seized fitting
Yup, working with three dimensional tools, and producing tangible results is not something with a virtual equivelant.
As for the pump, it might make a strange noise when both the autofill solenoid, and grouphead solenoid are working at the same time. If this is not the case, the resistance you mentioned makes sense to me as a possible culprit.
Have you adjusted the pump to 9 BAR as registered by the pump gauge? (the gauge at the bottom of most commercial machine double gauges) This is more or less the universal pump setting.
There's a flat head screwdriver adjustment in the end of one of the brass fittings in the pump. (if your pump is pretty old, it's under a brass cap fitting on the pump) This controls the amount of pressure created by the pump.
To adjust it, turn on the grouphead, and let it run while your both tweaking the pump adjustment, and looking at the pump pressure gauge on the machine. When it's at 9, stop the grouphead. It's easy, and makes a huge difference in shot quality.
Is the Pressure Stat tweaked right? This also makes a real difference. For espresso blends roasted barely past second crack, (pretty standard espresso roast profile I think, but I'm not a roaster) a pressure stat setting of 1.2 is considered by many to be ideal, but darker roasts respond better to a lower Pressure Stat setting, and a lighter roast to a higher Pressure Stat setting. (thanks Another Jim for that roast profile vs Stat setting tip)
To adjust the Stat setting, have the machine warmed up, and watch the top gauge reach it's peak. You'll hear the Pressure Stat click when the peak is reached, and the gauge won't go up anymore. Note where that peak is, ie. 1.0, or 1.3, etc. Then let steam out of the boiler until the gauge shows about half the pressure from it's peak point. While your watching the pressure go down, have your flat head screwdriver positioned in the top of the Pressure Stat adjustment screw. (in older Stats, the adjustment screw is the the bigger flat head adjustment screw that's accessed by taking off the cover of the pressure stat by unscrewing a pretty small flat head screw) When the halfway mark is reached, turn off the steam, and right after you do, turn the adjustment screw up or down as indicated by the plus or minus directions noted at the base of the adjustment screw. Each full turn of the adjustment screw represents roughly .5 BAR.
The Stat is usually a grey box with 4 wires going to it. two from the main switch, and two going from the Stat to the heating element. It's got a copper tube connecting it to the boiler.
The Stat is basically a diaphram that pushes the electrical contacts away from the element at the given pressure setting. Pretty cool stuff to take apart and learn from. Almost German/air cooled Volkswagen in concept.
Sorry to condescend if you know, and have done all this, but it makes a huge difference in quality if it hasn't been done.
Oh yeah, be really damn careful when you adjust the Stat! Also, if you've got to take the cover off the Stat to get to the adjustment screw, turn off the power to the machine while you do. I've had the 220 literally knock me on my ass when I touched the cover to the electrical contacts of the Stat! My typing speed has since increased by 50 WPM! I've got a parts machine of this same brand and type, and I've got all the parts in the noted diagram in working, but used form should you need any of them. I also work part time with a friend who sells espresso machine parts for all makes and models of commercial machines.
One of my minimized screens is the Norton Internet Security I'm currently doing online tech. support for. Ya know, I think I perfer mechanical tech support... Hmmmm....
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