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1991 500SL, 1998 E320, 2009 E350
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Discussion Starter #1
Just finished a decent amount of work on my '91 500SL with the M119/722.353 motor and trans in order to fix some leaks while the car is running on the driver side transmission. Every single part is OEM straight from the dealer. Replacement of parts included:
  • Transmission overload protection switch S65 (part number 0025454514) with all reaction valve o-rings/seals replaced as well
  • Upshift delay solenoid (part number 0003042790, same solenoid as the kickdown solenoid, just located right below the overload protection switch, believe it's part designation is Y3/2 but not 100% sure)
  • Upshift delay solenoid magnetic bolt with new o-rings/seals (part number 0003042890)
  • Vacuum modulator kit (part number 1262709179, came with plastic pin, cap, o-rings, adjuster, and of course the modulator)
  • New transmission pan (this doesn't really matter, but I guess it's important to note it was off.. part number 1262701012)
During the work, I ended up having to order the magnetic bolt for the solenoid since the old one was seized and all corroded. I left the ports open while I waited for parts (not the pan, just the OL switch with reaction valve and delay solenoid) but covered them up with tape to prevent any dirt or particles from somehow getting in there while they were exposed. Over the few days it leaked quite a bit of fluid out of the ports, maybe around half a quart? I mention this just in case its possible this allowed air to get into the system.

After receiving parts, I finished putting everything together. First installed vacuum modulator by putting the plastic pin into the trans, then the modulator next. Bolted down the retainer to 8Nm. Next put on the metal block that goes under the OL switch and what solenoid bolts into. Put the reaction valve in fine, only goes one way. Next the OL switch into the reaction valve which was fairly tight going in but it was also tight coming out. Finally, the upshift delay solenoid and tightened until it felt tight. Drained and dropped the transmission pan and swapped the new one on just in case the old one was warped to prevent any leaks.

I added around 3.5 quarts of transmission fluid and started the car. Ran it through the gears for around 30 seconds each. Put it back in park and let it warm up for a while. Checked the trans fluid and it was pretty low. Added another three-quarters of a quart to get it to correct level.

Attempted to take it out for a drive by putting it in reverse and found that it didn't want to move. Went into reverse gear fine and was responsive but it didn't really move. It felt like it was trying. Gave it a little throttle up to around 1100-1200 RPM, and it started to slowly backup. Upon releasing the gas pedal, it feels like the parking brake is on or the brakes are dragging. However, putting the car back into 'D' drive it moved back forward with no issue. Double-checked the trans fluid and it seemed fine. At this point I didn't want to drive it because I wasn't sure what the issue is.

Any ideas? Could something involved with the reaction valve or overload switch have gone wrong where it affects brake band B1? I have not adjusted the vacuum modulator yet, I was planning on driving the car first and seeing how it drove before touching it but not sure how that would cause this situation, seems more likely an issue with the S65 switch or reaction valve since it contacts the brake band.

The funny thing is, I still have a small leak from the same area so I'll have to look into that again.

Prior to this work, about 3-4 weeks ago I did a transmission service using an OEM filter with Mobil 1 ATF D/M (Dexron III). Drove perfect and had zero issues.

At the same time, I also did a full suspension overhaul with a few maintenance items on the engine itself. I figured I'd throw all this in here just in case somehow it could cause someone to think of an idea.

Replaced:
  • Front lower control arms
  • Front/rear shocks with B4 Bilsteins
  • Front/rear springs with H&R lowering springs
  • Strut mounts
  • Wheel bearings
  • Fan clutch
  • Voltage regulator
  • Belt tensioner and belt
  • Transmission cooler hoses (front rubber ones)
The parts highlighted in blue boxes are all the transmission parts I replaced.. #71 is the vacuum modulator kit, including all those individual pieces
2621912

2621913
 

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1991 500SL, 1998 E320, 2009 E350
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53 Posts
Discussion Starter #2
In an attempt to come up with ideas.. I double checked part numbers I ordered.

Did I install the wrong overload protection switch? I ordered part A002-545-45-14 which says "[048] As of transmission 3 536878" in the notes of the EPC. However, my transmission number looks to be ending in "3 472464" which would mean I should have installed A003-545-25-14...

Great. Appreciate the dealer telling me I ordered the wrong part number. What kind of damage could I have caused? Do you guys think it will be fine? I ordered the right part number and guess will see what happens.... That is so disappointing. :(

2621962

2621961
 

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1991 500SL, 1998 E320, 2009 E350
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Discussion Starter #3 (Edited)
Bump. Any ideas are really appreciated guys.

Replaced with correct parts today and it didn't help at all. Actually now, it seems worse with the correct switch. Putting it into reverse basically won't do anything now. Before, revving it slightly above 1100 RPM or so would get it creeping backward until I let off and got the brake feeling. Now, even revving up it won't move at all.

It turns out the correct overload protection switch is actually longer than the one I installed first. So I doubt that did any damage at all. I'm starting to think it may be something with the vacuum modulator? I tried to adjust the vacuum modulator quite a few clicks clockwise to see if it'd make any difference but it didn't.

I pushed the car back in neutral and tried to just drive it to see what would happen. Seems okay at first until it tries to shift, but then it gets a weird dragging feeling (still kind of like braking) and then it feels like it's trying to shift but can't. A few seconds later it kind of slams into gear. Once it shifts, it feels okay until it tries again. Drove it immediately back home. Only got about 50 feet before the 2nd->3rd shift and felt that.

Put the car in reverse, and tried to push it back. It feels like it's in park still. Pushing in neutral is just fine.

The only idea I have now is the vacuum modulator. Does anyone know if that could somehow cause these issues? Having the incorrect one installed or something?
According to EPC.. part 126-270-91-79 (the whole kit) should work. But another part 126-270-43-79 is listed as well with 126-270-91-79 being "optional". Part 126-270-43-79 with the plastic pin # 70 in the EPC diagram looks like what came out of the car but I've seen that it has been updated around different forums so I thought 126-270-91-79 was the better "option". But now I see that under WIS, there's a footnote for modulator 'A' for 07/92 and below, and 'B' for 08/92 and after. When I removed my vacuum modulator, part 59 on the WIS diagram did not come out with it but it looks to be the same for either modulator. Can someone confirm that the whole 126-270-91-79 kit (with pin # '76') will work with my transmission?

Edit: vacuum modulator part numbers should be interchangeable. Going to set trans fluid pressures with a gauge this weekend to adjust the modulator correctly and see if that helps, but I think there's a bigger problem.


EPC Diagram for my VIN
2622665




WIS Diagram for Vacuum Modulator R&R
2622664



If anything at all pops up in your head please let me know.. kind of don't know what to do at this point.
 

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1995 SL320, 1995 SL500, 1998 C280, 2004 E500 4matic
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I hate to tell you, but all the symptoms you are describing sounds like a time for a full transmission rebuild. You can certainly try this https://jenniskens.livedsl.nl/Technical/Tips/Files/722.3 slipping or no reverse.pdf for the reverse, Inside transmission though, B3 clutch pack is responsible for the actual reverse Whatever It Takes Transmission Parts, failed clutches would certainly do that... The fact that you are slipping forward too - not a good sign...

Vacuum modulator affects the "firmness" of the shift, kick down solenoid would also have no affects the issues you are dealing with.

If I had your issue, I would first inspect that valve body as outlined in the first link, then, I would personally even go as far as getting a used valve body (in known working order, it is around $100 or so).

And yet, deep inside, I believe it is time for your 722.3 to be rebuilt. Let us know if you find a solution otherwise. Good luck!

Regards,
D
 

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1991 500SL, 1998 E320, 2009 E350
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53 Posts
Discussion Starter #5
I hate to tell you, but all the symptoms you are describing sounds like a time for a full transmission rebuild. You can certainly try this https://jenniskens.livedsl.nl/Technical/Tips/Files/722.3 slipping or no reverse.pdf for the reverse, Inside transmission though, B3 clutch pack is responsible for the actual reverse Whatever It Takes Transmission Parts, failed clutches would certainly do that... The fact that you are slipping forward too - not a good sign...

Vacuum modulator affects the "firmness" of the shift, kick down solenoid would also have no affects the issues you are dealing with.

If I had your issue, I would first inspect that valve body as outlined in the first link, then, I would personally even go as far as getting a used valve body (in known working order, it is around $100 or so).

And yet, deep inside, I believe it is time for your 722.3 to be rebuilt. Let us know if you find a solution otherwise. Good luck!

Regards,
D
Thanks for the response. Been hoping someone will throw something out there. I assumed this would probably be necessary, but was hoping to exhaust all other options first. Doesn't seem like there's much else I can do though. I will definitely take a look over that link you posted. May as well go ahead and pull the valve body since I'll most likely be removing transmission anyway. Any ideas on what could have happened that could've destroyed it? It was running and shifting perfect prior to these repairs.
 

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1995 SL320, 1995 SL500, 1998 C280, 2004 E500 4matic
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...Any ideas on what could have happened that could've destroyed it? It was running and shifting perfect prior to these repairs.
It is hard to say... Everything with in these gearboxes is mechanical, so it ether works or it does not, no electronics. Bands, steels and clutches...

The valve body, in my book is a "pandora's box", even dealer hardly list any parts to be replaced individually (other than K1 and K2 pieces) and one pretty much has to buy the assembly. Is it possible that some dirt piece got dislodged and wedged itself somewhere with in the the maze those channels and paths? I believe that it is possible.

What I can tell you from personal experience, even after I rebuilt my 722.364 box, the slipping was still there (after the fluid got to the operating temperature), and I replaced EVERYTHING, using the most complete master kit.

As a final "let's try" I ended up purchasing a known working good factory rebuilt valve body from someone (and as a bonus, it was from W124 e400, so it had the inherited permanent 1st gear start valve body). Issues solved, beast!!!. Still I'm glad I rebuilt the box.

The good thing about the valve body, can be removed in 10 min... Maybe, just maybe this https://jenniskens.livedsl.nl/Technical/Tips/Files/722.3 slipping or no reverse.pdf would do the trick? I would also go as far as bathing this valve body (once off the car) a good cleaner bath, maybe even ultrasonic bath?

Regards,
D
 

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1991 500SL, 1998 E320, 2009 E350
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Discussion Starter #7
It is hard to say... Everything with in these gearboxes is mechanical, so it ether works or it does not, no electronics. Bands, steels and clutches...

The valve body, in my book is a "pandora's box", even dealer hardly list any parts to be replaced individually (other than K1 and K2 pieces) and one pretty much has to buy the assembly. Is it possible that some dirt piece got dislodged and wedged itself somewhere with in the the maze those channels and paths? I believe that it is possible.

What I can tell you from personal experience, even after I rebuilt my 722.364 box, the slipping was still there (after the fluid got to the operating temperature), and I replaced EVERYTHING, using the most complete master kit.

As a final "let's try" I ended up purchasing a known working good factory rebuilt valve body from someone (and as a bonus, it was from W124 e400, so it had the inherited permanent 1st gear start valve body). Issues solved, beast!!!. Still I'm glad I rebuilt the box.

The good thing about the valve body, can be removed in 10 min... Maybe, just maybe this https://jenniskens.livedsl.nl/Technical/Tips/Files/722.3 slipping or no reverse.pdf would do the trick? I would also go as far as bathing this valve body (once off the car) a good cleaner bath, maybe even ultrasonic bath?

Regards,
D
Thanks for the info that is helpful! I'll definitely be giving the valve body a deep cleaning just to try it before going all out. How hard is the rebuild of the trans and what kit is the best to order, that would include mostly (or all) OEM parts?
 

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1995 SL320, 1995 SL500, 1998 C280, 2004 E500 4matic
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Thanks for the info that is helpful! I'll definitely be giving the valve body a deep cleaning just to try it before going all out. How hard is the rebuild of the trans and what kit is the best to order, that would include mostly (or all) OEM parts?
Rebuild process is very straight forward, I ended up watching 40-50 hours worth of youtube videos, on 722.3 722.4 and 722.5 just so I can be "familiar" with it, and with proper literature, it is very much garage DIY. I have all the links saved, when I get home, will get everything from laptop bookmarks, will post here.

Regards,
D
 

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1991 500SL, 1998 E320, 2009 E350
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Discussion Starter #9
Rebuild process is very straight forward, I ended up watching 40-50 hours worth of youtube videos, on 722.3 722.4 and 722.5 just so I can be "familiar" with it, and with proper literature, it is very much garage DIY. I have all the links saved, when I get home, will get everything from laptop bookmarks, will post here.

Regards,
D
That would be amazing! Once again, thank you for the help. You're the only one that has replied so far lol
 

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1995 SL320, 1995 SL500, 1998 C280, 2004 E500 4matic
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That would be amazing! Once again, thank you for the help. You're the only one that has replied so far lol
Someone will indeed chime in. I've not seen @MAVA our resident transmission guru. I know he was moving, but he is a wealth of knowledge and inspiration for sure!

Based on your prior posts, you obviously "familiar" with tools and not afraid to use them, so... Here is the information dump.

Parts - one can get all the bits and pieces from the dealership, however, I've used Precision International "Banner" kit. These rebuild kits can be purchased here


or here


Inspect your steels, mine were shot, so I replaced all of them as well. I don't believe purchasing the master kit with stills is a good idea, as one would need to carefully calculate the basic variances in the overall clutch packs to achieve a proper thickness of the assembly. And individual steels of "unique" to your transmission may need to be purchased individually. Details of those to be found in PDF...

Do replace both brake bands B1 and B2... I've used re-lined B2 unit from Whatever It Takes Transmission Parts and B1 NOS from this guy (he still has them) Brake Band Front B1 Automatic Transmission 1262701662 1262701862 Mercedes | eBay

Helpful threads:

Removal


Needs


Everything


Videos:

K2 Drum overhaul


Other 722.3/4/5 videos



The following 3 - Russian (I'm fluent, but trust me, mute it, turn on Pandora or Spotify and have at it)



АКПП 722.4 Мерседес Инструкция по Ремонту и Сборке.

Mercedes Benz W202 C280 Transmission 722.424 Teardown

PDF:

Your rebuild/specs manual




Good luck! And let's hope it is just the valve body for now!

Regards,
D

If any visuals would help, the gallery of my own rebuild when I was restoring the car...

 

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1991 500SL, 1998 E320, 2009 E350
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Discussion Starter #11
Major update!!

I ended up taking my previous work apart again just to make sure everything was fine before going full tilt rebuild. Pulled the overload protection switch, and found the reaction valve to be extremely stuck in the slot. I ended up being able to pull it out with some needle nose vise grips after some rotating and staring while contemplating life. I put my phone camera up in there to see if it looked fine considering it was so jammed in there, and I found that the pin on the end of the reaction valve had somehow pushed itself down below the tapered seat of the B1 brake band, rather than seating in the brake band itself. It caused the bottom part of the band hole seat to become slightly deformed. I am not sure how this didn't happen with the incorrect overload switch I first installed but I guess that doesn't really matter at this point. However, it was not enough to completely ruin the band as it felt fine pushing it by hand and the pin was able to correctly seat into the band after some finessing. It was difficult to keep the pin perpendicular to the valve and prevent it from drooping when putting the valve in which is how it ended up missing the band seat. Some vaseline and precise movement and two attempts later, it was able to seat correctly. Because of the deformed seat it made it more difficult to do. If I had paid more attention in the first place I could have avoided this. I thought that because the seat was tapered and the tapered pin was so big that the chance of it not seating in the band was not plausible. Turns out I was wrong. Lesson learned to not take simple jobs as so simple.

The car goes into reverse with zero delay as it did before the job, drives great. I did play with the modulator pressure prior to pulling the overload switch and reaction valve just because it was easily accessible (I knew this would not be the reason behind the no reverse, but figured I would just check anyway out of curiosity). I ended with an experimental value just to see if that affected anything so I do need to set it back to the factory spec of 4.0 bar (722.353 transmission with TWC/upshift delay) per WIS. I set it around 50psi as experimental, while 4.0 bar is around 58psi. It definitely is a little soft after the test drive so setting it to factory spec should make it run perfect.

I'm assuming I took some life out of the transmission after this situation, so I won't be surprised when it does prematurely fail on me permanently and call for a rebuild. I drained and refilled trans fluid already once, and I ordered another filter and more fluid just to change it again in case any material is floating around in there.

Happy ending, but I still have a slight leak somehow from the brand new OEM pan and gasket which I'm not sure how that makes sense. I'll address that with a good cleaning and another gasket when I swap the filter. :)

Duh_vinci, I added and downloaded all of that information you replied with for future reference as I'm sure I'll need it one day. Thank you for that. I may just buy another 722.353 trans on the side and rebuild it myself just to have the spare. That info is valuable and I'll be using it eventually!
 

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1995 SL320, 1995 SL500, 1998 C280, 2004 E500 4matic
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Wow are you lucky!!! Glad to hear the good news!

...Happy ending, but I still have a slight leak somehow from the brand new OEM pan and gasket which I'm not sure how that makes sense. I'll address that with a good cleaning and another gasket when I swap the filter. :)
Regarding this leak from the "factory gasket" technically, that should not happen, as it is a thick rubber gasket, and being new... Do check B1 and B2 piston seals for leaks. Before the rebuild, I've had to change both of those in my car, but not before replacing that main pan gasket twice, as the leak and wetness "looked" like it was from the gasket - it wasn't, not in my car.

It is very difficult to see, I had to turn the phone on Video mode and shove it in the tunnel just to see... Here is 1 example of mine:

leak by Duh_Vinci, on Flickr

Fluid from that leak will collect enough and run all along the edge

IMG_20180415_162501 by Duh_Vinci, on Flickr

...then run/drip making it appear as if it was a gasket... So I would definitely recomend getting there with the mirror/phone to inspect both, B1 and B2 seals.

For now, again, glad everything worked out!

Regards,
D
 

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Discussion Starter #13
duh_vinci,

I was kind of worried it was leaking from one of those spots as it seems very difficult to change those seals while in the car. How was that job? I assumed it wouldn't be possible to change them without dropping the transmission.

I used a whole can of carb cleaner around the transmission, started the car and just laid down there with a mirror for 2-3 minutes before I found the source. It was the vacuum modulator which was new with the new OEM O-ring. Somehow, the small leak also somehow got around to the other side of the transmission too which made it appear as two leaks. Crazy how far a little transmission fluid can travel. I took the modulator back out and I just so happened to have an extra aftermarket seal in my box of parts I had ordered. Kind of strange since the OEM o-ring seemed fine and seated. The new seal and a re-torque to 8nm fixed the leak thankfully. Let it idle in the driveway for a solid 10 minutes and not a drop of fluid leaking anymore.

I also drained the transmission pan and refilled to help clear anything out.

Now I can finally move on and enjoy the car after the all new suspension upgrades and maintenance done!

Well kind of, still going to swap the filter and change fluid again just for safe measures.
 

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1995 SL320, 1995 SL500, 1998 C280, 2004 E500 4matic
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Once again, you are lucky! Removal of the modulator is nothing like the PITA of B1 removal, while transmission still in the car. But is it doable? Yes, yes it is... No way I was going to drop the tranny over the $5 seal ring.


B2 started to leak shortly after... But that one has a very weak spring load, so much easier, and still, while in the car...

Enjoy your car, you deserve it! I often take longer drive home through the country roads, just so I can enjoy the car (and I do), and today, 75F, sunny day, no exception.

Regards,
D

P.S. Good on you for sorting it out, persistence pays off!
 

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93 SL500, 95 SL320, 96 S320, 98 S500, 2002 E320 4Matic Wagon & A little 91 5.0 FORD Mustang
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I'm posting very little DuVinci in school for 13hrs a day and slammed on wknds working on old domestic cars-that my life for the moment...

The 722.3 I rebuilt one 8 months ago, and I too had valve body problems the customer toyed with different valvebodies and got one to work. Mercedes no longer sells valve bodies. I would just convert it to 722.6 and spend a few bucks more and time chasing some parts and covert the cars to 722.6.I plan to do it to with my own controller by around summer. Plus the 722.6 has around 700Nm(on a V8/V12 tranny) torque capacity where the 722.3 has about half that...

Martin
 
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