Thanks to this forum for giving me enough information to start my repairs. My eight year old Grohe shower valve 34-436 was dripping. I could not find the O-ring repair kit mentioned above at any dealer or even the Connecticut Grohe distributor. However, two of the three I talked to said that the solution was replacement of the complete stop valve assembly, not the O-rings. The other did not offer a comment. It seems the cost of the assembly is $160 (not sure if that's for a pair or not). I e-mailed Grohe tech service (see
http://www.groheamerica.com/s/25_40...hp?if_url=http://12.130.64.173/contactus2.htm) and asked if O-rings only would do the job. They said I should replace the whole stop valve assembly and sent a pair to me under warranty. P/N 08 355 00M. My experience follows. Do it at your own risk. I suggest that you get the valve assemblies from Grohe and then use a plumber if you have any trepidation.
Make sure you mark each part as to the order removed and which side faces forward. Use the diagrams at the locations listed below to help you:
http://db.grohecatalog.com/upload/p_explo/E34436US.jpg
http://db.grohecatalog.com/upload/p_spare/sp34436.gif
You will need a 17 mm socket to remove the stop valve assembly. Since the stop valves are spring loaded and push into the assembly, it does not have to be a deep socket.
Replacement is a little tricky because the whole volume control assembly (including the stop valves and yoke) wants to push outwards until the retaining ring that holds the volume lever is replaced. When the assembly moves out too far, water squirts out of the holes as mentioned in a previous post. Since you have to turn on the service stops before replacing the escutcheon, volume control lever and retaining ring, it becomes impossible unless you shut off the water to the bathroom first.
The squirting water is a normal consequence of the stop valve design and is usually prevented from happening by an O-ring internal to the valve. When the valve is pushed out too far, the O-ring becomes useless and hence the squirt of water. This will not happen with the volume control lever retaining ring in place unless the yoke plate attached to the stop valves is not adjusted properly (perhaps this is the problem observed in the previous post). I suspect that the hole is there to relieve air pressure internal to the stop valve as the yoke pulls it in and out. However, if the O-ring should fail, it will be a heck of a mess that you won't detect until the walls or ceiling show signs of water damage. I hope I'm wrong about this observation, but I don't think so.
You must adjust the yoke assembly before replacing the escutcheon. This means you first have to put the yoke, volume control lever and retaining ring in place without the escutcheon and adjust the yoke position by turning the white Teflon ring (using the volume handle) counter clockwise until it stops. This is the off position. Mark the position of the white ring at that point. Then disassemble and reassemble with the escutcheon in place and positioning your mark properly. Don't forget to turn the service stops on. Turn the bathroom supply on after assembly.