2 Group Gaggia Tell Restoration - Page 8

Equipment doesn't work? Troubleshooting? If you're handy, members can help.
OldNuc

#71: Post by OldNuc » Oct 04, 2019, 7:31 am

I suppose that is what happens when no one realizes there is leaking seal for multiple years, nice mess.

User avatar
IamOiman

#72: Post by IamOiman » Oct 04, 2019, 7:13 pm

I went out today to get some GUNK original engine degreaser to see how it would fare. I found out trough trial and error that it works well to soften the grease if not remove it. Afterwards I rinsed the pistons vigorously and placed them in a vinegar bath. In tandem I took my spatula pick to gently scrape off the surface gunk. I used a little scotch bright for the upper portion. These tools allowed me to nicely clean up my pistons and am pretty satisfied with the outcome.

Probably the most interesting thing was the color of the GUNK being pink!

Image
Image
Image
Image
-Ryan
I'll throw my portafilter in the ring
LMWDP #612

OldNuc

#73: Post by OldNuc » Oct 05, 2019, 8:37 am

I would get a gallon of EVAPORUST from the parts store so you can get all of the rust out of the swivel joint. It will remove it by converting to elemental iron which you can flush out with high pressure hot water, does take some time to act though. Gunk is an interesting soap that does at least get the process going.

OldNuc

#74: Post by OldNuc » Oct 06, 2019, 6:36 pm

Special lube for the upper internals.

I have figured out what the original lube was and what/were to find a modern NSF H61 replacement. As soon as I get some part numbers for believable small quantities I will post the info. This is a heavy industry produce and the smallest commonly available quantity is a 5 gallon bucket full.

User avatar
IamOiman

#75: Post by IamOiman » Oct 06, 2019, 6:46 pm

Really? That would be pretty cool actually. What would be the advantage of using that over something like silicone grease? I am not sure if I need 5 gal LOL
-Ryan
I'll throw my portafilter in the ring
LMWDP #612

OldNuc

#76: Post by OldNuc » Oct 06, 2019, 9:02 pm

The problem is that the oil used was unique to each producer in detail and is way out of style except for specialized applications characterized by sustained high temperature, moisture and/or water proof, very tacky so it stays put, rust and oxidation inhibited, high film strength. There is a bit more but generally it has various names that it was listed under such as: Steam cylinder oil, cylinder oil, open worm gear drive oil, open gear drive oil, closed low rpm gear and worm drive oil,and automotive transmission and rear end oil.

Side note modern GL-4 or GL-5 oil is not the same thing in any way. Silicone anything meets none of the original criteria.

There is no commonly available 4oz or 8 oz tubes made. I can find 14oz grease gun cartridge of the stuff though. My issue right now is that the selected product must meet all the original criteria and be NSF H1 and originate from a known supplier of products that actually meet the specs published.

The reason the old Italian stuff stinks is they used a suffer compound for the EP additive.

This is far from a common item in small quantities and as it is quite thick at room temperature and very tacky it is unpleasant to work with. I have ISO 1500 steam cylinder oil here for the steam engines but it lacks some of the other features needed.

What we are looking for is formulated for open gear drive food processing machinery used in the older large processing plants.

This works though: https://www.amsoil.com/shop/by-product/ ... e=GXCCR-EA This is the modern iteration of the original. If it is not tacky then it will promptly liquefy at operating temperature and run off. The group top reaches over 212F and that is way past the fail point for most grease. Disk brake grease will not work either.

Remember, it was well into the late 60s - early 70s before all the various lubricants were covered by published standards. Previous to that each producer had their specific product lines with proprietary specs. As this type of lubricant was a very small and diminishing market ther never was a standard for it.

User avatar
IamOiman

#77: Post by IamOiman » Oct 07, 2019, 7:52 pm

That is very interesting, I did not even think of what they used for lubrication inside the group! I presume I would be applying this in the gasket stack where the piston would slide along with the bottom group sleeve just under the stack?

Also, I used my evaporust to good effect, and the only thing I have left to do with the pistons is the inlet holes where the water goes into the pistons. On one of my pistons all holes are blocked with grime (tested by trying to blow air through each of the six holes while holding open the piston valve). What would be a good way of approaching this blockage?
Image
Image
-Ryan
I'll throw my portafilter in the ring
LMWDP #612

OldNuc

#78: Post by OldNuc » Oct 07, 2019, 8:10 pm

The seals and associated spacers use DC-111 silicon. The bearings, rack, rack pivot, and the pinion get the high temperature cylinder oil with the EP additive, R&O additive, and beef tallow.

Keep in mind this group was designed in the late 30s and was built to use what is now a lubrication technology that was designed for steam engines, open gear drive industrial machinery, and worm gear drives. when all of this was dreamed up lubrication compounding was unique to each different compounder. The present material has been slightly modified by using an aluminum thickener so it will pass the NSF H61 requirements.

There should never bee water above the piston but it will be hot and high humidity.

I try cleaning out little ports first with a heavy needle and if that fails a hand turned small drill bit. It is a slow as you go issue with plugged ports to prevent unfortunate accidents.

User avatar
IamOiman

#79: Post by IamOiman » Oct 08, 2019, 10:38 am

I was able to clean them out using some very small drill bits. I initially used a 57 AWG drill bit to make the initial hole through the crud, twisting by hand, followed by a 55 AWG bit to clean up the hole even more. Finally I took an air compressor nozzle and sprayed out the remaining loose gunk. The photos attached show how deep I had to go to clear out the gunk.
Image
Image

At this point I am pretty satisfied with my cleaning of the groups and internals besides replacing the gasket stack and acquiring the correct grease for the racks/pinions. Based off of Old Nuc's response I will try his suggestion since that grease is not terribly expensive.
-Ryan
I'll throw my portafilter in the ring
LMWDP #612

OldNuc

#80: Post by OldNuc » Oct 08, 2019, 10:57 am

When you build the piston seal stack the following will get a good initial seal.

You use a piston and rack assembly alone to do this.

Build the stack with all gaskets and spacers etc wiped the a very thin coat of DC-111, just enough to make a shine.

Install compression nut just contacting the stack.

Take piston and rack assembly and slide into stack after a shine coat of DC-111 on piston, this should be loose and drop right through the stack on its own weight.

Tweak the compression nut so the gasket contact is tight enough that the piston will just not drop through. At this point you have the initial adjustment. It is possible due to variations in seal diameter that at minimum compression you are already tight enough. This is a trial and error process.

Once the piston and seal stack are set you can finish construction the upper mechanism with reasonable assurances it will not end up full of water.

On first heat up keep checking out the bottom of the group as the system heats up and pressurizes, if there is a leak tweak the stack compression nut.

Those ports can really fill up with ossified fuzzy seals and outher gunk. The drill works very well for digging this stuff out.