1994 S320 No forward gear engagement - Mercedes-Benz Forum
Reply
 
LinkBack Thread Tools Display Modes
post #1 of 11 (permalink) Old 03-17-2013, 01:46 PM Thread Starter
BenzWorld Newbie
 
Date registered: Aug 2010
Posts: 3
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
(Thread Starter)
1994 S320 No forward gear engagement

Hello,

I have a 1994 S320 with a 722.508 transmission. When I shift into any of my forward gears (2 3 4 D ) there is a slight drop in the RPM's and when I give it some throttle the RPM's rise but there is no forward movement of the vehicle. Reverse is working as it always has and works fine.

What would be my next step in troubleshooting this issue?

Thanks,

John
redbeard13 is offline  
Sponsored Links
Advertisement
 
post #2 of 11 (permalink) Old 03-17-2013, 10:17 PM
BenzWorld Junior Member
 
MikkyB's Avatar
 
Date registered: Mar 2013
Vehicle: S320 W140 series & 260E W124 Series
Location: Australia - QLD
Posts: 18
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
It could be the metal pins in the gearbox not connecting, in which case may just need a spray of contact spray, or the pins themselves may need replacement, either way, it doesn't mean a re-build, but will need pulling apart, in which case may be a bit expensive.
MikkyB is offline  
post #3 of 11 (permalink) Old 03-17-2013, 11:09 PM
Moderator
Outstanding Contributor
 
MAVA's Avatar
 
Date registered: May 2006
Vehicle: 93 SL500, 95 SL320, 96 S320, 98 S500, 2002 E320 4Matic Wagon & A little 91 5.0 FORD Mustang
Location: Sacramento, California & El Dorado Hills, California, USA
Posts: 7,791
Mentioned: 37 Post(s)
Quoted: 1222 Post(s)
Lifetime Premium Member
I just rebuilt my 722.5(my self), and the B2 piston may be the problem. The piston o-ring could be worn out. The B2 is external on the transmission, but your forward clutches could be worn too.

Look up the document called master.pdf, and look at the troubleshooting section.

Martin
MAVA is offline  
Sponsored Links
Advertisement
 
post #4 of 11 (permalink) Old 03-17-2013, 11:14 PM
BenzWorld Junior Member
 
MikkyB's Avatar
 
Date registered: Mar 2013
Vehicle: S320 W140 series & 260E W124 Series
Location: Australia - QLD
Posts: 18
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by MAVA View Post
I just rebuilt my 722.5(my self), and the B2 piston may be the problem. The piston o-ring could be worn out. The B2 is external on the transmission, but your forward clutches could be worn too.

Look up the document called master.pdf, and look at the troubleshooting section.

Martin
Martin is the Oracle, so i'll shut up now lol :P
MikkyB is offline  
post #5 of 11 (permalink) Old 03-18-2013, 07:48 AM
Moderator
Outstanding Contributor
 
MAVA's Avatar
 
Date registered: May 2006
Vehicle: 93 SL500, 95 SL320, 96 S320, 98 S500, 2002 E320 4Matic Wagon & A little 91 5.0 FORD Mustang
Location: Sacramento, California & El Dorado Hills, California, USA
Posts: 7,791
Mentioned: 37 Post(s)
Quoted: 1222 Post(s)
Lifetime Premium Member
I drove by Oracle yesterday; The buildings are a architectural icon off the 101 Hwy in the San Francisco Bay Area.
Attached Thumbnails
Click image for larger version

Name:	Oracle.jpg
Views:	306
Size:	64.3 KB
ID:	502704  
MAVA is offline  
post #6 of 11 (permalink) Old 03-18-2013, 09:29 AM
Moderator
Outstanding Contributor
 
MAVA's Avatar
 
Date registered: May 2006
Vehicle: 93 SL500, 95 SL320, 96 S320, 98 S500, 2002 E320 4Matic Wagon & A little 91 5.0 FORD Mustang
Location: Sacramento, California & El Dorado Hills, California, USA
Posts: 7,791
Mentioned: 37 Post(s)
Quoted: 1222 Post(s)
Lifetime Premium Member
Okay John,

I'm no genius, but our Aussie Friend thinks so...

First things first.. Like all would say? How fresh is your Transmission Fluid? Up to the level? Recent filter?

Do you have reverse? Now, pressure is everything in a transmission, no cooler to radiator cross contamination? this will be a slippage on all gears. The main oil pump on the transmission could be damaged too.

Download the master.pdf document. On page 7 the troubleshooting section will outline transmission component problems. The document is good for 722.3-722.4 & 722.5 Transmissions. Study the master document to familiarize your self.

See post 26:

https://www.benzworld.org/forums/w140...when-cold.html

Now, before you go nuts chasing B2 problem or the "metal pins" problems. Check the vacuum lines going to the transmission, and test them for vacuum with your finger while you accelerate the engine. Next, disconnect the bowden cable at the throttle-It is a ball-joint-you can use a screw driver-It is easier with a fork like tool-A plastic door panel spoon works the easiest. Check the bowden cable for it's travel(1 inch travel) and it has a springy feel. The springy feel is important as this bowden cable goes to the vacuum modulator which actuates a active piston on the valve body.

If the Bowden Cable and Vacuum lines check out okay.

At the back of the transmission is a black round connector(about 1inch in diameter) make sure it is plugged in. Underneath the transmission filter are three(on the 722.5) wires(green, black and white) terminate make sure the Philips screws are tight.

Lastly, you can remove the valve body piston plates for a broken spring. The B2 Piston can be removed from the outside(it is the four inch round plate) on the right side of the rear of the transmission. The link below on the 15th photo shows the black round seal that hardens-up(on 722.5 behind the black seal is a metal sleeve in the photo-722.5 has a plastic one-it will look yellow). The piston shaft should be smooth with miniscule small smooth waves(no sharp ridges or large waves).

How to Replace Your Oil Cooler Lines


I personally, do not think your problem is inside the gear train or clutches(but I'm not saying the clutches are worn) Your problem may reside on the B1, B2 and valve body. If you are a DIY'er, you can inspect the problems. You do not DIY! Visit a transmission shop.

Martin
MAVA is offline  
post #7 of 11 (permalink) Old 03-18-2013, 05:18 PM
BenzWorld Junior Member
 
MikkyB's Avatar
 
Date registered: Mar 2013
Vehicle: S320 W140 series & 260E W124 Series
Location: Australia - QLD
Posts: 18
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by MAVA View Post
I drove by Oracle yesterday; The buildings are a architectural icon off the 101 Hwy in the San Francisco Bay Area.

MikkyB is offline  
post #8 of 11 (permalink) Old 03-19-2013, 09:14 AM Thread Starter
BenzWorld Newbie
 
Date registered: Aug 2010
Posts: 3
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
(Thread Starter)
Thanks for your detailed help Martin. I have the feeling that this is a pressure issue and you have made my next step clear. My fluid is clean and does not smell burned so I do not think that this is a friction problem inside the transmission.

I have used this site many times since I joined in 2010 and this is the first problem that I have encountered that has not been in the archives that was easy to find. My goal here is to update this thread periodically to document my progress and identify the problem and fix it.

Thanks again to this community for all your help.

John
redbeard13 is offline  
post #9 of 11 (permalink) Old 03-19-2013, 10:04 AM
Moderator
Outstanding Contributor
 
MAVA's Avatar
 
Date registered: May 2006
Vehicle: 93 SL500, 95 SL320, 96 S320, 98 S500, 2002 E320 4Matic Wagon & A little 91 5.0 FORD Mustang
Location: Sacramento, California & El Dorado Hills, California, USA
Posts: 7,791
Mentioned: 37 Post(s)
Quoted: 1222 Post(s)
Lifetime Premium Member
John,

You are welcome. The Master document will help all who do not have the electronic 722.6 transmission.

Best of luck,

Martin
MAVA is offline  
post #10 of 11 (permalink) Old 05-23-2013, 02:04 PM Thread Starter
BenzWorld Newbie
 
Date registered: Aug 2010
Posts: 3
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
(Thread Starter)
Hello again!

I have finally had some free time to look into my Transmission issue and have done the following:

A. I have removed the B2 piston on the side of the trans. The black seal on the inside is pliable and does not appear to have any damage to it. The B2 piston has the large heavy spring (towards the outside) and is not broken and seems intact. There is a small round piston (about 20mm in diameter) in the center of the B2 piston that has a light (low pressure) spring in it and feels "ok".

B. I have removed the valve body and inspected the B2 shift valve for sticking and found the spring pressure light (low pressure) and the piston action to be smooth. I have also inspected the rest of the valve body and all of the other pistons are smooth and have intact springs and smooth action. All check valve balls are in their correct location and are not gummed up. The fluid passages seem to be clear and the trans fluid does not have any grit in it when rubbed between my fingers.

My next course of action is unclear to me at this point. Any ideas or input at this stage would be welcomed and appreciated.

Thanks,

John

Last edited by redbeard13; 05-23-2013 at 02:09 PM.
redbeard13 is offline  
Sponsored Links
Advertisement
 
Reply

  Mercedes-Benz Forum > Mercedes-Benz Sedan Forums > W140 S-Class

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Mercedes-Benz Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in











Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 

Title goes here

close
video goes here
description goes here. Read Full Story
For the best viewing experience please update your browser to Google Chrome