Leaking Grohe model 34-436.

great posts!!! I have zero plumbing skills but I fixed the leak with the help of this blog. you're all invited to dinner. Thanks!!!

Grohe 34436 - Water from the two screws holding the stopvalves to the guide plate

KT444 said:

Thank you for the response. I did get a deep well socket and cleaned out the stop valve. I tried the shower and the pressure is great. However, when I tried to put the valve back together, a strong stream of water comes out of the stop valve split screws. I was wondering if you have an idea as to what I am doing wrong. Also, I don't understand why there are holes in the screw caps for water to come out since it can only go into the wall.
Thanks for your help.

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Hi, I have the same problem with water coming out from the two screws that are holding the stop valves to the guide plate. I contacted Grohe. To solve the problem, they told me to turn the on/off handle 8-12 times to get out the air that are trapped inside the stop values. I tried it but the water is still coming out. I am waiting for Grohe to see what else to try. In the mean time, how did you solve the problem or does anyone know how to solve this problem?

I have also tried to see if there is any adjustment with the position of the guide plate, and it doesn't seem to have any play for adjustment.

I appreciate any info you have that can help me solve this problem. Thx.

FWIW, I have this in a shower (12 years old) which started dripping. Grohe was no help and IMO gave wrong advice. Eventually ordered the STOP VALVES (835500M) online from Riverbend Home. Replaced them and now all is well.

No need for deep socket to remove the old ones (12 years old) as the protruding piece could easily be pushed in so a Standard depth socket would work.

For did assembly follow the instructions for maintenance in the Grohe brochure on their site.

The most likely cause of leakage in the 34.436 unit is the piston (stop valve) center o-ring, M3 x 6.5. To remove it, I use a pick tool to pull a portion out of its groove, then cut with a razor blade and remove. Replacing the M3 x 6.5 I found to be very difficult. So I made a tool shown in following photos. The Sharpie cover is slightly undersized O.D. vs the brass tube, but it works with a fillet. I cut the brass tube with a Dremel cutter wheel; all sharp edges removed and sanded smooth. Remove the "pocket clip" from the Sharpie and sand smooth, then shorten the Sharpie's length (optional). I glued the tool together in two steps:

1st glue the dowel into the sharpie cover in a vertical position, and with the tubing close to its intended final position. This was done to ensure the dowel would make it into the tubing. 2nd, butter the portion of the dowel that extends from the Sharpie cover, then slip the buttered dowel into the tubing and align on center and hold in vertical position. These steps are done to avoid epoxy flowing beyond its intended location inside of the tubing.

Now lube for sliding slide the tubing over the piston shaft as far as it will go, slide a new M3 x 6.5 o-ring over the Sharpie and to the end of the tubing. If sized appropriately, the o-ring will drop into its groove. All of this is a "piece of cake" using the tool. I have not changed any of the M2 x 8 o-rings, but obviously it will work well for that task as well.

As of the last o-ring change, I note that probably the groove should have lube in it as well as coating over the o-ring. My believe is that the o-ring I.D. could also be an access location for leakage as well as "roughing" and "starving grease" on the O.D. of the o-ring.

I trust the photos will make up for any lack in my description of the tool fabrication and use. I have 3 of the 34.436 units, two used at least every other day. I end up relubing and/or changing the o-rings in each stop valve about every 2 years on average. While the thermostatic valve is nice, I doubt I would ever select to install these complicated units in the future. We have Grohe faucet controls installed at our sinks the same 8 years as the shower units; the sink units have never required any maintenance whatsoever!

Yeah, this is an old thread, but it's been really helpful. I had a leaky Grohe of the same model mentioned here, but after replacing the stop valve washers, I only got pure hot water out of the shower. Others here have reported having this problem.

In my case, it was not a defective thermostat cartridge (expensive!). If you removed the cartridge and put it back in (to inspect or clean), but accidentally tightened it using the smaller nut groove (two slots closest to temp control dial) instead of the larger full hex nut, you locked the cartridge into "full hot." That inner nut groove is for calibration (not for tightening the cartridge in its housing). If you did this (like I did: DOH!), just turn it back a little bit clockwise. You can recalibrate by using a thermometer to adjust to 100° when the temp dial is set for 100°. Clockwise makes the mix colder; counter-clockwise makes it hotter. If you happened to just order a new cartridge ($150) out of frustration, that would fix the problem (overtightened calibration nut) but it may not have been necessary!

I am trying to remove the stops. I have tried using a 17mm socket short handled socket wrench but cannot get either side to break free. Are they reverse threaded? I am afraid to put muscle on them for fear of braking something.

Any help would be appreciated.

ElroyP said:

Are they reverse threaded? I am afraid to put muscle on them for fear of braking something.

Any help would be appreciated.

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They are not reverse threaded. Be careful though. Is there a way to hold the valve while doing this?

Yes, do I use a screw gun to back them out? Everything I have removed came out easily. I was not expecting to have to use much torque to remove these from the valve body.

I let it sit and came back, had to use some elbow grease but they backed out. I changed the o-rings, reinstalled the parts, the shower no longer drips. Thanks for the help.

Help! Trying to remove parts to reach the "Stop valve", but the "Stop ring" and "Sleeve" are stuck and very hard to move, as shown in the photos below:


Do I need some special tool ?

Yours looks slightly different than mine, but that whole handle assembly should just slide out. There was a large metal snap ring holding mine on firmly .... had to pop it off carefully using a screwdriver. After the handle assembly is off, the stop valves are readily accessible. As someone else mentioned, a standard 17mm socket will remove a stop valve, but you have to push in on the spring-loaded protrusion.

Is the a direct replacement of the 434-34 and 434-36? I have three, i have replaced the o-rings and within a few months the a dripping again. I have even polished the seats with a fine Emory cloth with no success. I can get to the back of the shower fixtures for replacement. We like the adjustable temperature settings, but are over the drip in the shower. Thanks for the help.

About to replace the stop valves for a 3rd time (maybe 4th?). Have replaced the cartridge once after it was vibrating like crazy. Attached are some instructions.





Hope that helps!

Well, replaced stop valves again which stopped the dripping but one stop valve screw would not come off without a lot of force - probably took me 15 minutes of trying things. Ended up using vice grips on the handle of a screw driver for the extra leverage. After putting things back together, the volume lever was very very hard to move so might have damaged something. It is over 30 years old so I guess time to move on to an upgrade/replacement, probably Moen moentrol or posi-temp. If anyone has recommendations, please let me know. I think finding trim big enough to cover the existing hole might be the biggest challenge for a replacement.

A wide trim that cover many openings is the Moen TL2386EP for the Posi-Temp valve.

Thanks! Wow, that trim looks just like the Grohe trim and should fit perfectly!