Olympia Cremina stuck lever pin

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bwren

#1: Post by bwren »

I took apart a 87 Cremina today, that had sat idle for many years. Disassembly went smoothly in general, and potential problem areas like the sightglass came off without a hitch.

I disassembled the entire machine with one exception that is preventing me from servicing the group.

The front lever pin is rusted and just frozen in the piston rod. After removing the rear pin, and after giving the group/fork a good soak in Cafiza, I was able to pull the piston upwards and tilt the fork so that it was completely above the group head. In this position I was able to move the fork freely over the pin, but the pin is frozen where it meets the piston rod. I used food grade oil on the pin, then supported the piston rod on a block of wood - but multiple tapping efforts with a dowel on the pin would not budge it.

I finally tried my last choice - using a penetrating oil (AeroKroil). After 4 hrs, still no joy.

Any suggestions?

Sw1ssdude

#2: Post by Sw1ssdude »

More penetrating oil. and heat.

Dont worry about the penetrating oil too much. You can give all the parts a ride in the dishwasher, and they will come out antiseptically clean.
If you have a torch, heat the pin up (not glowing, but, like, REALLY hot), it will help the penetrating oil to... penetrate.

rinse and repeat.

next: hammer time!
Hammers come in all forms: lead, copper, rubber, steel... i'd use a steel hammer (deadblow hammers are cool, but still too much flex). Support the shaft in a way that it lays flat, and that the pin can exit on the underside. then tap it, gently, but insistent. if it moves, you can try to tap it back and forth, and loosen the rust. Otherwise: go to a machine shop and use their lever arbor press. this way there is less chance of peening the end of the pin.

you can also try grabbing the pin in a vise, and use the group as a lever to rotate the pin. as soon as it budges, you have won the fight.

once its out, clean the bore, and use new pins.
Lean Mean Caffeine Machine

bwren (original poster)

#3: Post by bwren (original poster) »

Sw1ssdude wrote:More penetrating oil. and heat.
Dont worry about the penetrating oil too much. You can give all the parts a ride in the dishwasher, and they will come out antiseptically clean.
I have had good luck using Cafiza in my ultrasonic bath to clean espresso machine parts with machine oil.
Sw1ssdude wrote:If you have a torch, heat the pin up (not glowing, but, like, REALLY hot), it will help the penetrating oil to... penetrate.
Yes, I do have a torch (had to use it to get the screw off the valve seat washer), but I was a bit concerned about the heat damaging the chrome finish.
Sw1ssdude wrote:next: hammer time!
Ha! after starting with a rubber mallet, then hammer/dowel, I graduated all the way to a small flat-head steel hammer directly on the pin (with the piston rod supported, and pin sticking up all the way through the fork), but no luck. Yes I am concerned about peening the ends of the pin, though I could always cut off an end with a hacksaw if necessary.
Sw1ssdude wrote:next you can also try grabbing the pin in a vise, and use the group as a lever to rotate the pin.
I never thought of doing this - great suggestion! There is not a lot of pin to grab while having enough clearance from vise to fork to prevent surface marring, but I will give this a try before going to a machine shop as the last resort. I may also try this technique using a vise grip on the pin. I will report back in a couple of days when I have some time to attack this project again.

Sw1ssdude

#4: Post by Sw1ssdude »

Do not use vise grips.

you will have to both balance the group and the grips AND apply force. its an easy way to slip and punch your knuckles into sharp edges on the group, or scratching your chrome. i tried this multiple times on other projects, with very little success. clamp, strap or tie one part down, and operate on the other.

if you manage to use a vise you can focus on twisting the pin loose (do not use rubber or aluminum protectors on your vise jaws, go directly for the serrated jaws, and REALLY clamp it down. this side of the pin will be f*cked, so grab the one side you already hammered on).

Send some pictures of your restoration if you can!
Lean Mean Caffeine Machine

danmc

#5: Post by danmc »

I had the same issue on a Cremina group. I used penetrating oil and then a rubber mallet and a punch working both sides of the pin. I worked it for a couple of sessions over the space of two days and the pin finally came free.

Dan

bwren (original poster)

#6: Post by bwren (original poster) »

Reporting back. Took the group head to an aviation mechanic's friend, who offered to spend a couple of minutes looking at this. He had a couple of presses in his shop, including a pneumatic one. After looking at it, he said it would require making a custom jig built to use one of his presses.

He tried applying heat with a propane torch to the SS shaft around the pins (avoiding the fork), followed by Kroil, and then trying to tap out the pin. No success.

He was not able to get enough material in the vise to make your suggestion work - holding pin in vise, and rotating head.

He also tried putting the fork inside the vise, with one vise jaw on a socket against the fork over one end of the pin, and the other jaw pressing against the pin. No success.

I was advised to keep trying heat followed by penetrating oil. Just gave it another go at home, but no success. Will keep trying.

bwren (original poster)

#7: Post by bwren (original poster) »

Success! Perseverance paid off. Thanks for all the advice.