Cimbali Group Head leak

[b9drinker]

I've got a nice and compact Cimbali M32 Bistro DT1 that's had its group head seal replaced by an engineer (not faulty or leaking - just 6 months usage). Sadly it blew 45 minutes after use. I've tried replacing with Cimbali group head seals of 8.5mm and 9mm conical without success. I've inserted 2 x .8mm shims/spacers as well and it still leaks.

Can you let me know what's going wrong please. Is my group head distorted? Or is it my porter filters (both single and double) that are worn (although there's no sign of undue wear and tear)? BTW, I thoroughly cleaned out the recess before inserting seals etc, and second BTW, it didn't leak like this before.

Many thanks

[artman]

I didn't notice this post, I replied to your other one.

In addition, make sure your group collar is correctly installed and tight. There is nothing really in the group that can go wrong.

The group and collar are huge chunks of brass, very solid.

Cheers

[Javaphile]

Quoted from original thread for clarity:

Did you get the conical seal? Is the group nice and clean where the seal sits? On mine a very thin film of "stuff" forms behind the seal over time (despite regular back flushing and cleaning ) but it's quick and easy to remove the collar and seal and give the group a good clean/scrub. If you remove the collar and seal you will soon see what's going on.

Cheers

Java "Original thread closed" phile

[b9drinker]

Quoted from original thread for clarity:




Java "Original thread closed" phile

Apologies Javaphile

[b9drinker]

I didn't notice this post, I replied to your other one.

In addition, make sure your group collar is correctly installed and tight. There is nothing really in the group that can go wrong.

The group and collar are huge chunks of brass, very solid.


Cheers

Cheers Artman

I agree it's a big chunk of brass. Just can't fathom out why the seal should leak though. I've cleaned it thoroughly, and seated the seal squarely using the porter filter.

I inserted a 9mm conical seal with 2 x .8mm shims yesterday - and it still spitting water out. Aaaaargh. The porter filter yesterday was locking in and tightened up so the handle was in the 6 o'clock position, it's now in the 4 o'clock position. Very confused.

[artman]

Have you taken the collar off to have a good look to make sure it's squeaky clean? Tried it without the washers? Doesn't really matter if the PF locks in at 5 or 4. Is the collar centred correctly and the three collar bolts tightened evenly?

Does it leak with another basket/blind?

Seems strange, there is nothing really to this group, it's a very simple and robust design.

Cheers

[b9drinker]

Artman thanks for your advice

The collar is squeaky clean - as far as I can see. There's no debris up there. I'll check to see that the collar is centred correctly today.

It leaks like a sieve without washers as it does with a single or double PF. Same problem when using a blind.

It also loses water down the waste pipe - a lot more than normal. In fact I'd say I lose half the water when it's brewing. If that makes sense. The waste pipe feeds into a half gallon bucket, that bucket never use to be quarter full. Now it's full at the end of the day.

No idea what the engineer has done. Sorely tempted to buy a new group head and start afresh.........

[artman]

Is yours the rotary pump?

It sounds like you may have an issue that mine had. The pump bypass (brew pressure adjustment) was jammed causing the pump (and hence brew ) pressure to go sky high and the over pressure valve was trying to dump the excess pressure by dumping the water into the waste whenever the pump was activated. The pump flows a lot of water so pressure at the group was way over 15 bar (it maxed out one of my gauges ) This would also mean that the group seal will struggle to seal the extra pressure.

If this is the issue it is easy to fix if your are that way inclined. You can remove the pump bypass and check the piston moves freely. Mine was jammed up, I stripped it, cleaned it and lubed with food grade grease and it was good to go. You will need to reset the brew and OPV pressure.

Cheers

[b9drinker]

Cheers Artman - you are a font of information.

I'm not too sure if mine has a rotary pump - but the symptoms you've described are very similar.

Sorry to be slow witted here, but where is the rotary pump and bypass? I'm fairly capable of stripping the bypass, just not sure where it is, plus I use it 6 days a week in my tea room.

Do really appreciate your help by the way - cheers

PS is this the rotary pump/bypass I need to locate and fix? Part number 25?

http://www.astramgroup.com/EspressoM...FAEMA-FA20.htm

[artman]

No probs. the link you sent, the part number 25 is the pump which bolts to the motor (part 22). This is a rotary pump setup, the motor is quite large, can of baked beans type size. And they operate almost silently. The vibe pumps are very noisy in comparison and quite small, about the size of a couple of boxes of matches. Google "ulka pump" for images. If you take the panels off your machine it will be obvious which pump you have.

If you look at all the variations of part 25 in your link, the very left domed type nut is the pressure adjuster/bypass. The outside nut is the lock , the inside bolt/screw is the pressure/bypass adjustment. On mine, the setup is slightly different, have a look at this thread:

http://coffeesnobs.com.au/brewing-eq...-question.html

and specifically the pic in this post: http://coffeesnobs.com.au/brewing-eq...tml#post263615

If yours is the same, unbolt the entire adjustment mechanism (green nut) and see if you can move the piston (pics further down). If you dont touch the locknut/adjuster, then in theory if your pressure was set correctly prior to the issue, you can free the piston, clean, lube etc and bolt back in and it will be back to what it was. its simply a spring that preloads the bypass.

Not sure if the domed nut setup on the pumps in your link are any different?

Its all quite straight forward if you are the tinkering type, just take your time and note the order of the parts.

ideally get a pressure gauge so you can set the brew pressure (9bar) and over pressure valve (12 bar) correctly. Pullman "hires" one: http://coffeesnobs.com.au/brewing-eq...tml#post513396

Cheers

Cheers

[artman]

Forgot to mention, you can adjust the pressure while the pump is running and see the changes immediately on the gauge. Standard electrical safety, live machine disclaimers etc etc etc...

Cheers

[b9drinker]

Many many thanks mate, much appreciated. Shall be having a look later today or tomorrow - that's if my customers don't lynch me for switching the machine off and denying them their coffees!!

Cheers

[b9drinker]

Artman - in my eyes you have the status of a god. The OPV was well and truly stuck. Only took me 15 minutes to remove it, 15 minutes in citric acid (vinegar), 15 minutes back and and Roberts your uncle.

Many thanks mate - so very much appreciated.

Testing it tomorrow proper when we open up tea room, to see whether the GH/PF seal still leaks after I change it. Will keep you updated.

[artman]

No probs at all, glad I could help.

I presume you mean the pump bypass was stuck? The OPV is what dumps excess pressure when the pump is creating too much pressure.

Cheers

[b9drinker]

No probs at all, glad I could help.

I presume you mean the pump bypass was stuck? The OPV is what dumps excess pressure when the pump is creating too much pressure.

Cheers

That's the one. Working fine now - just need to change group head seal when it arrives. Can't understand though why I'm having to use a 9mm seal with a .8mm paper gasket - do you think my porter filters need changing?

This is what I used before fixing the valve

La Cimbali GROUP SEAL,GROUP GASKET - Detailed item view - Coffee machine spare parts,Espresso coffee machine spare parts Jura spare parts