1976 La San Marco Tipo 75 two group

A haven dedicated to manual espresso machine aficionados.
User avatar
IamOiman
Team HB

#1: Post by IamOiman »

The third and last machine from my most recent shipment is this La San Marco Tipo 75. I intentionally wanted a two group as I like using them in the winter and fall. Perhaps down the road I can fit in an Export version 8) . Initial state looks pretty promising on the outside. As a two group machine it has an additional steam valve and a cup tray valve compared to the 1 group. The only damage I can note is a small dent in the body panels on the top left of the machine when looking from the front. It was already present when I purchased the machine and did not occur during transit. The traffic cone orange panelling really sticks out but it has splotches of random paint on it. I am still debating whether to keep the panels original. The LSM 75 uses the same knobs and portafilters as my earlier LSM 6X machine except for the water inlet knob, which is a button rather than an actual tear drop knob.










To take off the panels you need to start in the front and remove the two panels that cover the group heads. Four screws secure the vertical front panel to the frame, while three screws (one was missing) secure the top panel to the front panel. Taking off these panels reveals two styles of groupheads. The left one has some play in the lever fork so I will be inspecting that one closely when I take it apart fully. Both groups have ID numbers stamped on the lower group piece, 9685 for the left and 7187 for the right.




To take off the rear panels a slotted bolt and two phillips screws need to come off on each side. The phillips screws also secure the backsplash to the machine, and to slide it off the hot cup tray valve knob needs to come off too. Once done the back panels come off by pushing the whole assembly forward a bit then lifting it up because there is a lip on the bottom rear of the assembly that slips into the frame for stability.



Inside I realized the pstat bracket was in two pieces, leaving the pstat hanging just by its pipe. This machine has an ANCC or similar number, but it does not use the same one as the Lombardy brands (like Faema, Gaggia, etc) because each region of Italy had their own ANCC/equivalent number list. This is why even though the machine is from 3 February 1976 the ANCC number is only 55338 (the San Marco ID tag is 26406) when my similarly aged 1979 Gaggia LL's ANCC number was over a million.






The boiler lid came off without too much hassle. I used my little impact driver to get the bolts loose, and nothing was really stuck even though there was a decent amount of surface rust on the bolts. There was old water in the boiler that drained out after taking the lid off.




The valves and pipes all came off too without issue. The valves themselves differ a little in how the pipe attaches, allowing the pipes to swivel, but the gaskets inside are the same as my LSM 6X and modern machines today. The groups came off after, and I left the group flanges attached to the boiler due to the amount of scale deposits accumulating from the old leaky gaskets. I will descale first before attempting to take those off.





The feet came off, which are the same shape as the LSM 6X. The bolts are horribly rusted so they will likely be replaced. At this point I was satisfied to the progress I made stripping the frame and moved everything into the basement.




Further disassembly will occur soon 8) .



-Ryan
Using a spice grinder violates the Geneva Convention
LMWDP #612

User avatar
IamOiman (original poster)
Team HB

#2: Post by IamOiman (original poster) »

I ran into a really, really bad problem for one of the groups during disassembly. First off I was getting the valves apart along with the other grouphead without issues. The valves allow the pipes to swivel, and are compressed by two conical teflon gaskets and a spring to keep the seal. There was a lot of grease on all the valves.






One group was fully taken apart. The pistons are the newer style with the big fat v gasket and teflon guide + brass ring. They are still designed to fully relax the spring before the compressing nut comes off the threads of the piston rod.



This is where the real big issue lies. The second group was mounted for disassembly, and I saw the piston rod start turning with the piston. This is not good, and with some inspecting I realized the little pin that prevents this from occuring failed, and I was actually unscrewing the piston rod from the top. This is really bad because there is far less thread for the spring to relax, and the group is not designed to come apart like that with the spring still installed. The piston is more stuck than the upper rod threads which is also an isssue because I cannot access the spring compressing nut that allows me to safely decompress the spring.



After speaking with someone who experienced this same issue I decided to try my luck and fully unscrew the rod from the top. I zip tied (these are pretty heavy duty but I will not openly recommend others doing this without understanding the risks and padding themselves in protection) the spring so they would hold back some of the force as the spring relaxed, and it seemed to do a good job as the piston and springs simply fell out without launching themselves when the thread ended. The other person said his piston dented a car in the garage from the force of release. I immediately placed the spring in my decompressor and relaxed it without issue.



Looking at the eye piece there was definitely a little pin that normally secures the piston rod, but it failed/sheared off and left some marks in the process. The piston is really stuck on the rod and I have not been able to get it loose yet. I will need to work on that more but I am just happy I was able to get the group mostly apart and not potentially need to replace an entire upper housing.





-Ryan
Using a spice grinder violates the Geneva Convention
LMWDP #612

User avatar
IamOiman (original poster)
Team HB

#3: Post by IamOiman (original poster) »

I managed to unscrew the piston finally. Both the piston and the spring compression nut were tightened way too much. I had to strike my spanner wrench with a hammer to unfreeze the threads, and before that I also did a few heating and quench cycles. I also had to tilt my spanner at an angle because the notches on the face of the piston are not cut parallel to the face, but rather at an angle. I also fished out the broken pin from the top. Seeing how tight the piston was screwed in I am not super surprised it snapped, but hopefully I can clean up the piston bore and related parts without issue. The random chrome flakes are from the piston bore, and it crumbled out in pieces during disassembly.


-Ryan
Using a spice grinder violates the Geneva Convention
LMWDP #612

User avatar
espressotime

#4: Post by espressotime »

I thought these LSM's were set up as an HX.Looks like this is a dipper.

User avatar
IamOiman (original poster)
Team HB

#5: Post by IamOiman (original poster) »

both this guy and my 6X are dippers, but I know of the HX machines you refer to. These models come in both HX and dipper.
-Ryan
Using a spice grinder violates the Geneva Convention
LMWDP #612

User avatar
espressotime

#6: Post by espressotime »

You could do one group with one spring and the other with two.
There's a slight taste difference.

tinroofrusted

#7: Post by tinroofrusted »

Fascinating thread, and great photos! Thank you!

User avatar
espressotime

#8: Post by espressotime »

You should make a tool to screw that piston loose. A C spanner ain't the right tool for the job. If you want to apply force use a wet piece of leather that you wrap around the piston and use a regular groove plier to screw it loose.

User avatar
IamOiman (original poster)
Team HB

#9: Post by IamOiman (original poster) »

You're right, normally I've been using a rubber oil strap wrench and a firm tug with no issues for the other two groups I've disasssembled. The pistons should not be as stuck as this troublesome one, and for ones in the future that also may fight me I can see what can be sourced around here or if I go and just try to make my own.

-Ryan
Using a spice grinder violates the Geneva Convention
LMWDP #612

User avatar
espressotime

#10: Post by espressotime »

For regular cleaning I use this 3d printed part.