Rebuilding the Oly twins... a saga - Page 3

[timo888]

About the spare parts for Cremina's I'm pretty sure atleast the top piston gasket on mine needs replacing but I'd like to find the gasket kit and do a complete overhaul. Mine is old but in very good condition.

I was thinking, as a treatment, I could find a food grade silcone lubricant that's water insoluable and also capable of restoring and sealing in a high heat, high vacuum environment. I found something that was perfect but the shipping charges on a $7 tube of the stuff would have been around $50. Too much. Can't find the link for it right now.

I got something out of California that seems to be o.k. Minimum order was $15 with a shipping charge of $8 USPS to Canada. Much more reasonable. It's in a syringe format. Bostik© N-S WT White Food Grade. No problems dealing with the company and the service was very good. Order has just been filled. Waiting on delivery.

http://www.aeroconsystems.com/Hillson/hillson.htm#types

What do guys think, though? Gaskets dry out over time and if they're totally gone, I guess they're gone, but if they're just dry you can restore them with the proper lube and it would save replacement. If that lube also acts as a sealant, so much the better.

I've used silcone spray on the rubber gasket around my car window when it started drying out and sticking and it didn't just act as a very good lubricant it also reconditioned the rubber.

Lubricants rated for "incidental food contact" are not, IMO, adequate to the task of lubricating piston-seals. You want something potable-water-system-approved. I'd look for a NSF61 rating. The listed applications for the Bostik are:

° Nuts, bolts, screws
° Pipe fittings
° Stainless steel fittings
° Valve stems and assemblies
° Pump gears
° Chain drives
° Gaskets
° Press fit assemblies
° Conveyor and oven bearings
° Packaging machinery
° Worm gears
° Slow speed or highly loaded bearings <500 RPM

Regards
Timo

[mogogear]

About the spare parts for Cremina's I'm pretty sure atleast the top piston gasket on mine needs replacing but I'd like to find the gasket kit and do a complete overhaul. Mine is old but in very good condition.

I was thinking, as a treatment, I could find a food grade silcone lubricant that's water insoluable and also capable of restoring and sealing in a high heat, high vacuum environment. I found something that was perfect but the shipping charges on a $7 tube of the stuff would have been around $50. Too much. Can't find the link for it right now.

I got something out of California that seems to be o.k. Minimum order was $15 with a shipping charge of $8 USPS to Canada. Much more reasonable. It's in a syringe format. Bostik© N-S WT White Food Grade. No problems dealing with the company and the service was very good. Order has just been filled. Waiting on delivery.

http://www.aeroconsystems.com/Hillson/hillson.htm#types

What do guys think, though? Gaskets dry out over time and if they're totally gone, I guess they're gone, but if they're just dry you can restore them with the proper lube and it would save replacement. If that lube also acts as a sealant, so much the better.

I've used silcone spray on the rubber gasket around my car window when it started drying out and sticking and it didn't just act as a very good lubricant it also reconditioned the rubber.

Please describe what your machine is doing or not doing that makes you suspect this need.

[mrgnomer]

Please describe what your machine is doing or not doing that makes you suspect this need.

Dribbling water out the top of the piston while warming up. It was actually Will at Home Espresso Repair that offered the diagnosis and it makes sense, retrofitted new boiler cap on old machine not withstanding.

[mogogear]

So what you need is a Piston SHAFT seal ( not to pick details -since there are two PISTON seals and one of them would be the upper)

[mrgnomer]

So what you need is a Piston SHAFT seal ( not to pick details -since there are two PISTON seals and one of them would be the upper)

From the Cremina parts list the upper gasket looks like it's called the piston seal and the bottom the piston head flat gasket. Is that the proper way of identifying the parts?

[mogogear]

The list can be confusing- I won't say what is the exact nomenclature- but there are two piston rings- they are identical and are installed with the "V's" facing opposite. Botton V down- upper V -up

There is also the grouphead gasket that seals the top of the basket, it has the slight rounded inside edge faced up.

[mrgnomer]

The list can be confusing- I won't say what is the exact nomenclature- but there are two piston rings- they are identical and are installed with the "V's" facing opposite. Botton V down- upper V -up

There is also the grouphead gasket that seals the top of the basket, it has the slight rounded inside edge faced up.

Thanks for the tips. Very helpful to know the orientation of the gaskets especially the grouphead since I'd probably take the old one off and not even think to look how it was put in. Something like that is easy to miss.

[timo888]

From the Cremina parts list the upper gasket looks like it's called the piston seal and the bottom the piston head flat gasket. Is that the proper way of identifying the parts?

The flat gasket fits around the outside the piston cylinder.

--piston rod seal (21.5x10.5x4)
--precision o-ring (24.99x3.53)
--two piston seals (45x35.5x7)
--flat gasket (58x48x7)

Regards
Timo

[mrgnomer]

The flat gasket fits around the outside the piston cylinder.

--piston rod seal (21.5x10.5x4)
--precision o-ring (24.99x3.53)
--two piston seals (45x35.5x7)
--flat gasket (58x48x7)

Regards
Timo

O.k., I think I get it now

2x piston rod seal, upper and lower, both the same dimensions
precision o-ring (24.99x3.53)-between group and boiler
flat gasket, a.k.a. grouphead gasket.

[timo888]

O.k., I think I get it now

2x piston rod seal, upper and lower, both the same dimensions
precision o-ring (24.99x3.53)-between group and boiler
flat gasket, a.k.a. grouphead gasket.

Yes, and since the two piston rod seals are designed for reciprocating motion, they face each other.

The newer Cremina adds a Zurcon wear ring (40x45x5.5) between the piston seals; the piston seals change from GACO to Variseal®; and the piston is capped by two flanges the removal of which makes installation of the seals much easier (and a big stretch would not be good for the spring in the Variseal).

Regards
Timo

[mogogear]

One last note: the newly designed psiton seals do NOT fit older designed pistons- Only Cremina 2002

[mogogear]

So while the group-heads are at the Chrome shop, I finished a couple of small tasks. Reinstalled the elements, and then mounted the boilers on the stripped and repainted frames. Drilled out the new rear holes for the power cord strain relief inserts.



And the "faceless" girls



Just a small note: I was thinking why the P-stat was raised and is on a shorter connection feed- Hmmmmm...then I think the simple answer dawned on me- perhaps just to be a little further from the heat of the element? Seems logical.

[peacecup]

Greg,

For what its worth, the Mater Pstat on the Export attaches directly to the bottom of the boiler:



I can't comment on the reliability or accuracy of it. I've never removed it to see how it works, and don;t have a pressure gauge to test it. Its the same model as on the Lusso, so timo or others could report. Regardless, my morning cappuccino today was delightful, and its about time for a ristretto

Walk slow,

PC

[mogogear]

Good Point Slow Poke My Bezzera is the same except on the side of the boiler...I dunno

[TUS172]

When I did the pressure gauge revision on the '86 I ended up lowering the pstat to just about the same location. The '67 has it in the lower position also. Perhaps in later years they just cut the length because it was not needed.
Have you considered the addition of a pressure gauge to one of yours?

[mogogear]

Not really Bob- Other than to set the p-stat with - It just doesn't interest me as a mod at this time...I am just boring that way

[Fullsack]

I think the quote for all of the brite work was $385. I'll double check and post some pics next week, after I get back from Rome.

http://www.home-barista.com/forum...so-bars-t3690.html

The brite work quote is $665, not $385, must have been wishful thinking on my part. I pick up the pieces Monday and will post pics.

[mogogear]

I pick up the pieces Monday and will post pics.

The pieces of your wallet are not going to be very interesting.....Oh, now I get it

[Fullsack]

Yeah, pieces of my wallet alright. This rebuilding stuff is not for the faint of pocketbook.

[Fullsack]

The brite work quote is $665, not $385, must have been wishful thinking on my part. I pick up the pieces Monday and will post pics.

I forgot, the original quote was to nickel plate the pieces for 2 machines. For the entire brite work for the one machine, it was $332.