Sight Glass Seal R&R

  • Indications: Water under machine, rust on expanded metal bottom cover, point source corrosion or scale at sight glass.
  • Tools Required: All of the aforementioned tools....wrenches screwdrivers, everything but the snap ring pliers.

This repair is the most invasive of them all. It requires complete disassembly of the machine, save the boiler and element. This is the repair most people hope they don;t have to do and for good reason and the general worry is that they will break the sight glass tube. This is usually not a problem as we have never broken a tube if it was not cracked to begin with and they always come out a lot easier than you think they would.

There are two different machine designs, differing in the construction of the top channels which supply the steam valve on the left side of the boiler and the sight glass and pressurestat on the right side. Earlier machines have a full brass square tube which extends the entire width of the machine. Our rebuild in this demo (1983) has only one half of this channel which supplies the sight glass and the steam valve is supplied by a copper tube which attaches directly to the boiler. There are slight differences in the rebuld process as well.

The first goal is to remove the front stainless machine cover to gain access to the sight glass from both the front and the back.

  1. Remove the machine cover panels after loosening the top boiler nut.
  2. Remove the entire steam valve faucet assembly by disconnecting the steam valve supply line in the case of the newer model using the 17mm and 12 mm wrenches, then hold the faucet firmly in one hand and use the 17mm to loosen the holding nut on the back plate. You may need the mallet to loosen this. Work the steam faucet out of the hole.
  3. In the case of the earlier model, remove the rear steam valve cap with the 17mm wrench and take off the copper crush washer. Work the faucet through the front plate. There is a O ring between the stainless plate and the steel frame.
  4. Remove the group by loosening the 4 cap bolts.
  5. Remove the screws from the bottom front corners of the face plate. The small nuts on the back are a little hard to get to so you may need a needle nose pliers to hold them still while you unscrew the screws from the front.
  6. Lift the face plate away and set aside.
  7. Using the 17mm wrench, loosen the brass pressure relief valve from above the sight glass assembly. Note the copper crush washer which may stay on the channel or on the collar of the valve.
  8. Loosen the nut on the pressure stat tube and remove the pstat by laying down beside the machine...unhook the wiires if you wish but it is not required.
  9. Loosen the brass sight glass retaining nuts fully.
  10. At this point you grasp the sight glass tube and twist it a bit to break it free from the old seals while pushing upwards to slowly push the tube through the seals. Keep the tube straight in relation to the housing. Be aware that you can break it if you move it too far back and forth. The challenge here is to get the tube moving and once it moves a little it becomes obvious that it WILL move and so it is just a matter of carefully working it out the top.
  11. Once the tube is out and safely put away (note of caution....soaking the glass in citric acid may soften the paint on the outside) remove the old seals upper and lower.
  12. Assembly follows the reverse by first installing the new seals in the housing sockets.
  13. Insert the glass through the top of the housing and slowly push through the seals (you may want to use a bit of lube here to make this easier, making sure the brass nuts are placed on the tube. You may want to start one thread on the nuts to make it easier to keep track of insertion without worrying about putting the nuts on at the last minute.
  14. Push and twist the tube all the way down into the lower seal. The top of the tube should be flush with the upper seal. Make sure the line on the glass tube is in the right orientation.
  15. Tighten the brass nuts until you feel resistance and then about a quarter to a half turn more. There is no need to hammer these nuts down as the fresh seal will expand under the nut to seal without that much tightening of the nut.
  16. Install the pstat.
  17. Install the pressure relief valve using a new copper crush washer. THIS is the one that you really hammer down.....tighten as tight as you can by hand and then use the mallet to get it as tight as possible.
  18. Install the front face plate using a small screwdriver and tool to hold the nuts in place.
  19. Install the group and tighten as in group R&R.
  20. Install the steam faucet, remembering to place the O ring between the stainless face plate and the frame if you have the older type. With the newer type simply install the faucet holding nut behind the steel frame and reattatch the steam supply tube. On the older machine install a new copper crush washer and then tighten the cap on the faucet thread and torque tighten as with the pressure valve.
  21. Once you have everything back together perform a leak test by heating the machine and observing for any hissing or water. The top crush washer sealed fittings can be easily accessed to tighten a bit more using the mallet. If you do have a leak at the sight glass it will likely not take much tightening of the brass nuts to seal it so worm a wrench in there and tighten until the leak stops and no more. Usually if there is a leak it will be one or the other of the crush washer sealed parts.
  22. When you have assured yourself that all is well, install the machine panels and finish by tightening the top boiler nut finger tight plus a little.


Olympia Cremina Rebuild Sight Glass Seal R & R Instructions Olympia Cremina Rebuild Sight Glass Seal R & R Instructions - Remove Steam Wand Supply LIne Olympia Cremina Rebuild Sight Glass Seal R & R Instructions - Removing Steam Faucet Olympia Cremina Rebuild Sight Glass Seal R & R Instructions - Steam Faucet off Olympia Cremina Rebuild Sight Glass Seal R & R Instructions - Removing Group Olympia Cremina Rebuild Sight Glass Seal R & R Instructions - Removing Pressurestat Olympia Cremina Rebuild Sight Glass Seal R & R Instructions - Removing Pressure Relief Valve Olympia Cremina Rebuild Sight Glass Seal R & R Instructions - Pressure Relief Valve loose with crush washer Olympia Cremina Rebuild Sight Glass Seal R & R Instructions - Removing Stainless Front Panel Screws Olympia Cremina Rebuild Sight Glass Seal R & R Instructions - Front Panel off with switch still attached Olympia Cremina Rebuild Sight Glass Seal R & R Instructions - Loosening Lower Sight Glass Nut Olympia Cremina Rebuild Sight Glass Seal R & R Instructions - Loosening Upper Sight Glass Nut Olympia Cremina Rebuild Sight Glass Seal R & R Instructions - Freeing Sight Glass from old seals Olympia Cremina Rebuild Sight Glass Seal R & R Instructions - Removing Sight Glass through top of frame Olympia Cremina Rebuild Sight Glass Seal R & R Instructions - Sight Glass Ectomy Successful Olympia Cremina Rebuild Sight Glass Seal R & R Instructions - Removing Old Sight Glass Seals Olympia Cremina Rebuild Sight Glass Seal R & R Instructions - Installing new Sight Glass Seals Olympia Cremina Rebuild Sight Glass Seal R & R Instructions - Installing Sight Glass Through top of frame Olympia Cremina Rebuild Sight Glass Seal R & R Instructions - Nuts on Sight Glass ready to install & tighten Olympia Cremina Rebuild Sight Glass Seal R & R Instructions - Tightening Lower Sight Glass Nut Olympia Cremina Rebuild Sight Glass Seal R & R Instructions - Tightening Upper Sight Glass Nut Olympia Cremina Rebuild Sight Glass Seal R & R Instructions - New Crush Washers & Seal Kit Olympia Cremina Rebuild Sight Glass Seal R & R Instructions - Install Pressure Relief Valve Olympia Cremina Rebuild Sight Glass Seal R & R Instructions - Tighten Pressure Relief Valve Olympia Cremina Rebuild Sight Glass Seal R & R Instructions - Install Front Panel Olympia Cremina Rebuild Sight Glass Seal R & R Instructions - Machine with Group, Faucet Installed

There are various and sundry small tasks to perform now and again, changing feet, lubricating the cylinder or the piston pins, or other maintenance tasks, but the above 4 jobs pretty much cover the possible rebuild or repair projects. We did not cover unexpected facets of these opereations such as replacing electrical connectors if needed or other complications which may arise. and thankfully we have not had to source and replace any electrical parts, but in general, all of the repairs are approachable and with some time and patience can be done successfully. If you don't have the right tool, take the time to get it before setting out on the job and it will go a lot better, likely since you will have more confidence, especially if it is you first time doing possible harm to your nice Olympia Cremina.

Please use this, in the spirit that it is intended, as a guide for your endeavours - Doug's teacher at tech school always said "There are at least a thousand ways to approach any task", and that is certainly true about rebuilding your espresso machine!


After years of rebuilding perhaps 100 Olympia Creminas and reviewing our full Cremina rebuild guide I am still content with the guide as a good primer on DIY Cremina  rebuilding.   This guide has helped many people go from nervous nellies about tackling such a job to competent Cremina mechanics, and we are so very pleased with this result!   We have added various videos and other small guides for specific issues and hope that these are helpful as well.  Now (9/23/2010... 6/29/2023)  we would like to offer some thoughts based on what has turned out to be extensive hands on experience at rebuilding Olympia Cremina espresso machines.

First, get your tools in order.

      We use only the mini snap ring pliers.  The black handle plier is ideal for inserting the rod seal seeger clip  as it comes out of the package.   The red handle plier is used on the lever pin clips.   Take the time to custom fit the tips of these pliers in the  lever pin clip holes.....scrape the paint from the tips with a blade and sand or file the tips to get a perfect fit in the clip holes (the older clips have slightly smaller holes than the new ones).   Use the ring plier at a direct 90 degree angle to the clip....once you are certain a good fit has been made of the tips in the clip holes open the clip very slightly and lift straight off the pin.
     If at all possible use only fixed size open end wrenches and avoid Crescent wrenches or other adjustables.   We do show crescent wrenches in our photos but this was done in an attempt to include the tool deprived individuals in the world of espresso machine repair. 
     A good  mechanic can  repair a car with a hammer, a piece of wire and a pair of pliers, and you can rebuild your Cremina with  about the same tools....but tool up and you will not regret it!

Parts Upgrades
     Over time we have constantly upgraded replacement parts.   These upgrades include a silicone group to boiler o ring simply lasts longer than the rubber part.   The use of a teflon ring at the pressure safety valve replacing the copper washer.   And the use of silicone o rings to seal the water sight glass upper and lower.    Silicone Piston & Rod U-cups (they are now red).   We did this in each case because the upgrade part was easier to install and more durable than the originals, taken from Olympia spec sheets as a guide.   For each case allow us to make a short guide to installation of these parts.....

Group to Boiler Silicone O ring

To install this part one needs to roll it into the seal groove on the back of the group.   Place one edge in the groove and grasp the other edge with your fingers and roll backwards so when you push the o ring into the groove it will be flat.   If you simply try to push it into place it will pop need to roll  the uninstalled side of the ring  so once installed it will not be twisted.   If it stays in place you have installed it correctly.

Pressure Safety Valve Teflon Ring
For us this upgrade is a big improvement over the copper crush washer.    Simply place the ring into the machined indentation around the safety valve hole on top of the sight glass and hand thread the valve into the socket.   Using a 17mm wrench tighten until snug.   No hammering is required.     Once you pressure test the machine you may need a bit more tightening of the safety valve if you detect a leak  or bubble but generally another 1/8 to 1/4 turn will seal.    If for any reason you need to remove the pressure safety valve you can re use the teflon seal over and over.    The copper washer was one of the most difficult seals to get completely leak free and we are glad to be shed of it!

Silicone O Ring Sight Glass Seals
This upgrade has been a vast improvement in the ease of installation of the sight glass.   We include 2 upper and 2 lower rings in our parts kit.   If you have a machine that includes the small brass washer under the sight glass nut then you will likely need only one top and bottom...if your machine has no brass washer under the nut then you will need to use 2 in both the top and bottom.      To install (after cleaning the threads of the brass sight glass nuts) simply push the 2 rings into the lower socket  then insert the glass through the top.   When the tube protrudes from the upper socket install the upper rings on the tube followed by the upper nut and work these parts UP the tube as you work the tube DOWN.   Place the lower nut on the tube before it enters the lower socket.   Once you have seated the glass tube all the way down into the lower socket start the lower nut.    Do not tighten it, just catch the first thread.    Then push the upper o rings into the upper socket using the upper nut as a tool.   Catch one thread of the upper nut.   It will help to put a drop of DOW 111 on the LOWER edge of the nuts before starting them (to lubricate the surface of the nut that touches the ring)..     Align the red or blue stripe in the back of the socket taking a visual from directly in front or a 90 degree visual when viewed from above.   Tighten the 17mm nuts with a wrench until snug in the upper and lower sockets until the glass can not be turned by hand.     Very simple installation compared with the old parts.

Pressure Testing
After completely rebuilding the machine it should be leak tested.    Fill the boiler half full and turn it on.    As it heats up wait, look and listen.   Any leak will be evident.      The usual suspect is the pressure safety valve and it may require a small tightening but will generally be easy to seal.    When the machine is hot be sure to lift the lever (with a vessel under the group) to assure that the piston and rod seals are seated properly.    Listen for any hissing or odd sounds.     

Re Tighten After Heat Cycling

We like to run a machine intermittently for a couple of days after a rebuild to give the seals a chance to seal and the metal parts a good period of heat so they can expand and contract a number of times.   After some period of heat check the fittings to make sure they are tight.     Remove the pstat and check the sight glass nuts for tightness, then replace the pstat.    Turn the machine over and check tightness of the boiler bolts, again using an X pattern to get them even.         You may need to check again in a few weeks time.  It is better to expect to address the sight glass seals again than to over tighten the nuts on a one shot deal.    Over tightening reduces the life of the seal and can lead to some severe headaches down the line for your next seal replacement, which WILL happen sooner or later  as long as you own, use, and enjoy the machine.

To do a DIY on it you more or less have to follow the circuit and eliminate possibilities as you go.
First check all the wires to make sure they are not loose or burned looking.
If there was no know overtemperature event then eliminate by logic a burned element or some tragedy of this order.
Start at the switch and unhook the two terminals on the top  orientation of the switch (the bottom two spade terminals come from the power cord and the top two are the cold side of the switch).   Using a multitester set on ohms check the switch.   When turned ON is there continuity through the switch?  Test with probes on lower and upper terminals on each side of the switch.    If switch good move on.
Go to pstat...the microswitch may be stuck.   When you push up and down on the silver U shape spring does the switch click?    When the machine is cold the switch should read continuity, or ON.    If it does not read ON then the little plastic button may be sticking.   Unhook wires and check with meter.   If this switch is working fine then move on to the thermal safety switch.
Unhook wires and check with tester.   It should read continuity   If so it is fine.
Go to element and unhook terminals (careful do not bend metal rods)  test with meter.  You should get a steady reading of 12.5 ohms with no wander of the reading.  This means element good,   Now put meter lead on one terminal and the other on the base of the boiler.   You should get NO reading and if you get an ohm reading with this test the element has a repairable short.     If you get ohm reading from terminal to base plate observe the behaviour of ohm reading....does it wander all over or remain steady?   
If you have no element short move on to the pilot light....unhook terminals and test.   It should read continuity...the light bulb is part of the neutral circuit and if the bulb is burned out it will not heat.

Those are all the tests and besides a bad power cord (which would throw your circuit breaker) it cannot be anything but these components I have listed and one must be bad and the repair is simple.   Take your time, don't break any parts and all will be good.  Let me know what you find out and we  can go through any and all solutions.

If you get stuck, have a crisis of confidence, or just need clarification just email and ask....always glad to help!

We hope this helps and by all means take your time and ENJOY THE ESPRESSO!!!!!

Barb and Doug

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