Leaking water around portafilter during extraction - Olympia Coffex

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suprolla
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#1: Post by suprolla »

I am trying to diagnose an issue on my newly acquired Olympia Coffex. It is missing the serial number plate, but the boiler is stamped 1983, and the grouphead is 49mm to match my Cremina. It is also red with the gold stripes, matching my Cremina. I used it when I first got it, but it needed major cleanup and a pinhole leak had to be fixed, so I went through each part of the machine, cleaning and replacing gaskets as I went along.

- Pump is an Ulka 50W EX5, with the gicleur in place.
- Boiler works great, I do not yet have the pressure gauge to see what the pstat is set to.
- scale at the bottom of the boiler kept the fill gauge lying to me - descaled, opened up, cleaned, new boiler gasket.
- original PF gasket was hard and coked - probably never backflushed. Cleaned with a pick and new gasket installed
- group o-ring replaced
- HX o-rings replaced
- sight glass seals were good
- Steam wand rotating seal changed, everything else left alone, no leaks
- Screen was removed and cleaned along with the inner shower block (?)

With the machine as it was, I was able to brew a couple shots, steam milk etc. Compared with the Cremina, the flow was fast, the dose needed was closer to 15g. It may have been my technique as well, since I don't need to tamp too hard for the Cremina.

After changing out seals and cleaning up as described above, I checked for any leaks (none). I attempted to brew again. The extraction starts off really well, then there is an audible clunk, extraction slows, the portafilter handle tilts, and water starts coming out around the top of the filter (clear water). The portafilter handle releases, but the puck is stuck to the screen at this point.

I have used the Cremina portafilter with Elektra double basket, as well as the original portafilter and Olympia double basket, both with the same result. As mentioned, the portafilter gasket is brand new and clean. It seems to build up pressure for some reason, and eventually find its way around the gasket (Looks like I also need a portafilter pressure gauge). The puck sticks when I turn off the brew flow, and the 3 way valve opens to relieve the pressure.

What, if anything else, can I check/replace/may need repair?

Thanks

PS: I am taking pictures as I go to show the progress of the machine semi-restoration, in keeping with some of the other awesome threads that helped me with mine.
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drgary
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#2: Post by drgary »

Roger,

It should increase pressure during brewing. Your machine probably has a flow restrictor in the line from the pump so pressure builds. The flow restrictor looks like a small disk with a hole in it. Here are photos of its location from a rebuild thread by RAS.





It seems you could back off the dose just a touch at that grind. Otherwise I wonder whether the new portafilter gasket fits properly. Do the portafilters crank in at the same angle? Is the gasket fully seated?

When a Maximatic is working properly the espresso is similar to what you get with a Cremina.
Gary
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What I WOULD do for a good cup of coffee!

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Eastsideloco
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#3: Post by Eastsideloco »

I agree with Dr. Gary. I wonder if the group head gasket and shower screen are seated properly. I don't know how else to explain those symptoms. From the sounds of it, the extraction pressure seem to reach a critical point, and then the water finds a path around the puck portafilter & basket.

One other thought: You could try the old auto mechanics trick to isolate the source of the "clunk." Get a piece of tubing-in an auto shop you would use a vacuum hose-and use this as a stethoscope. Basically, you put one end of the hose up to your ear, and move the other around during the shot. You may be able to isolate where the sound is coming from this way.

But I'd rule out a simple problem with the group head gasket first.

suprolla (original poster)
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#4: Post by suprolla (original poster) »

Thanks Dr. Gary and Dave, yes the restrictor is in place in about the same area as shown. Portafilters do go to the same angle. I have been down dosing as low as 12-13g with the same issue: starts extracting beautifully, then clunk of some sort, portafilter handle tilts downwards, and water/pressure starts escaping. As soon as the 3 way valve opens when I switch off, the handle tilts back up.

UPDATE: Took it apart again, and this time found a tear on the portafilter gasket along the inside edge about 1/4" long. I can't imagine how that happened. Looks like I will have to order a couple more for safekeeping.

Thanks
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cannonfodder
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#5: Post by cannonfodder »

That will do it. There is also a top and bottom to the gaskets. If you look at them there is a slight taper /\ is how they go in the group.
Dave Stephens

suprolla (original poster)
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#6: Post by suprolla (original poster) »

Still no luck, and now another gasket gone. This time I used the OEM type gasket seated in the group, pushed in with a blunt screwdriver, being careful not to damage it. The gasket is slightly different from the Orphan Espresso one in material and the shape. There is a slight chamfer on one side compared with the other which is square.



So again, after heating up, flush, pack 13g of coffee, with a light tamp with my thumbs on the tamper, lock in portafilter, then try to brew. This gasket is also destroyed with chunks left in the cup after trying to remove the portafilter.

Am I missing something in the screen setup? here's how they go together:



Currently waiting for the group to cool down before I remove it and examine the remnants of the gasket closely.

Mods, should this be in the Espresso Machine Forum instead?

Thanks
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cannonfodder
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#7: Post by cannonfodder »

You will get more hits in the espresso machine forum since this is a machine problem. Moved.
Dave Stephens

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Eastsideloco
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#8: Post by Eastsideloco »

Yes, you are missing the fact that the group head gasket seal seats into the roof of the group. You appear to have it flush with the shower screen. It needs to seat more deeply behind the shower screen. In other words, install the gasket first, making sure that it seats into the slot in the roof of the group. Then screw in the shower screen. The installation will be easiest if you lube the gasket with Dow 111; this will also help prolong the life of the seal.

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cuppajoe
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#9: Post by cuppajoe »

And make sure the chamfered side of the portafilter gasket is facing up, towards the group, and push it hard 'till it fully seats. Do hit it with a little Dow first, it will make the installation easier.
David - LMWDP 448

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suprolla (original poster)
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#10: Post by suprolla (original poster) »

I suspect, one of the ears are bent in the group head, causing pressure to bypass and squeeze out the gasket each time. Looks like I will be looking for a new brew head. The picture showing the gasket appears to be in line with the shower screen but it is setback into the little groove in the head. I do use DOW211 to coat before installing and go around to make sure it seats. At this point, I don't want to waste anymore gaskets on this head.

Considering my Cremina is already 49mm, I would prefer to stick with that size, but is there a benefit to going to the 54mm heads?

I can get a 54mm group from Cerini, but would need baskets and tamper, just about doubling the cost of my machine....or buy another Coffex for cheap if I can find one, again doubling my initial cost. I keep looking at that beautiful Pasquini in the For Sale and thinking I should have just gotten that one instead. I am about to surpass that price easily (something to think about, anyone else looking to do an eBay restoration).
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