Vacuum adjustments 1995 W124 E320 - Page 2 - PeachParts Mercedes-Benz Forum

ksing44 · #16 04-14-2007, 08:23 AM

I am going under the car to adjust the vacuum modulator. I purchased what I think is a pretty decent jack and some pretty good jack stands. I found them for a good price at Pep Boys and they seem to be heavy-duty tools for a very reasonable price.

3-Ton Torin Big Red Jack, Model# T83002 - $49.00
3-TonTorin Big Red SUV Jack Stands, Model# T43006 - $29.00

My car shifts pretty good when warm, but I still have some flair when it is cold, depending on my driving style. If I am taking it very slow through the neighborhoods on my way to work, then I do get nice shifts. If I go very fast, I also get good shifts. With intermediate acceleration, however, I still have a shift flair when my car is cold. I am hoping that adjusting the vacuum modulator will complete my repair and eliminate all of the flair. If not, then I guess I will just be doing an experiment to see how long I can drive with a flair before my transmission completely fails.

It is a shame, if I can’t get this fixed easily. I didn’t have a flair until the dealer replaced the kickdown actuator and Bowden cable and also replaced all of the seals on the transmission “while they were in there”. I wish I had just ignored the stupid engine light, since I had absolutely no symptoms before the dealer did the “repair”. Another mechanic told me that sometimes you get erroneous codes that cause you to fix things that aren’t really broken. This time it seems an erroneous code caused me to break something that wasn’t broken.

brewtoo · #17 04-14-2007, 08:47 AM

Quote:

Originally Posted by ksing44

You know how Mercedes has that absolutely ridiculous thing of the delayed shift when cold, which I absolutely hate, well that may have messed me up a little this morning when it was cold.

This is easy to disable. Do a search on it.

Also, when you say they "replaced all the seals," what do you mean exactly? Did they remove the transmsission? What seals were replaced?

ksing44 · #18 04-14-2007, 10:24 AM

Quote:

Originally Posted by ksing44

I am going under the car to adjust the vacuum modulator. I purchased what I think is a pretty decent jack and some pretty good jack stands.

Holly smokes, I was scared under there. I think I can get used to it, but man crawling under there isn’t for the faint of heart.

One issue is finding a good place for the stands and even the jack. For the jack I used the OEM jack point, but the jack is right in the way of where I want to go. For the stands I went under the front control arms (I think that is what they are called). I just can't seem to find exposed frame parts or axles or anything around to get in under for rigid support. If you guys have ideas, please help me. I am leaving the jack in place, set just to secure the vehicle if the stands failed. I also put my snow wheels and tires in there, just as an additional safety.

I don’t really like it under there, but I did crawl in and look at the transmission. I think I see the plastic cap. Please look at the picture and tell me if I really do pry that thing off and try to find the T thing.

You know, I think I may need a real mechanic. It doesn’t look like this is going to be too easy after all. My dealer doesn’t even seem to know about this and my Indy didn’t want to mess with the transmission. I may have to go to the “Mercedes Specialist Indy”, even though I think he was too anxious to fix my head gasket leak 2 years ago. I didn’t do it and my regular Indy thought it wasn’t an emergency. It has been 2 years and has not gotten worse, so I think I was right to walk away from the specialist.

Any advice will be appreciated. I may go do this anyway, even without more advice.

stevebfl · #19 04-14-2007, 10:50 AM

The adjustment takes about 30 seconds, do you have a gas station with lifts that will lift the car for you. Pay them a fee. Labor book time for lifting a car for an observation is typically .3 hours. If they get 100 an hour (not likely in a gas station) that would equal 30 bucks.

Remove the rubber cap (hoping you have the original universally adjustable modulator, not the white plastic capped limited adjustment one) and pull the adjusting tee handle outward, just enough to clear the castellations it was sitting in. If it comes out to far don't worry just put it in anywhere it will insert (four fold symetry) and count your adjustment from that spot. I would turn it one full revolution and leave it till you have driven it a few days. If you don't recognize a difference you could do it again. If it shifts too harsh in any gear you might consider backing it off to a midpoint and just living with your condition.

ksing44 · #20 04-14-2007, 12:00 PM

Quote:

Originally Posted by stevebfl

Remove the rubber cap (hoping you have the original universally adjustable modulator, not the white plastic capped limited adjustment one) and pull the adjusting tee handle outward, just enough to clear the castellations it was sitting in. If it comes out to far don't worry just put it in anywhere it will insert (four fold symetry) and count your adjustment from that spot. I would turn it one full revolution and leave it till you have driven it a few days. If you don't recognize a difference you could do it again. If it shifts too harsh in any gear you might consider backing it off to a midpoint and just living with your condition.

Thanks again Steve for getting back to me. I was worried about it, but I went for it anyway. I do have the white plastic cap and the T did fall out on the ground, but I was able to get the T back in and I turned it one full revolution clockwise. There was also a rubber gasket thing that I had to put back in and the white plastic cap is a bit of a pain to get in place with the little bumps in just the right place, but I did it!

I took the test ride and absolutely could not get it to flair! The car was still cold during the ride, but it wasn’t really all that cold today, so I may have to wait until a cold morning to pass final judgment. The car also shifted great after it was warm.

I can tell a little difference in the firmness of the shift and I like it. Actually, I kind of wish I had gone for 2 full turns, since it seems like it might be nice to feel a really firm shift. It doesn’t slip in or anything, but I think I might like it even firmer. Does having a firmer shift decrease wear on the clutches in the transmission? If it did decrease wear, even though it is a hassle to get under my car and do it, I think I might be willing to go back under to do it one more time.

Thanks over and over again Steve!

Quote:

Originally Posted by brewtoo

This is easy to disable. Do a search on it.

Also, when you say they "replaced all the seals," what do you mean exactly? Did they remove the transmsission? What seals were replaced?

As for replacing “all of the seals”, I have to admit I don’t really know exactly what it means. On the work order, I have a list of 9 different seals, a gasket, the kickdown solenoid, vacuum line, trans cable (which is the Bowden cable I guess), and it says they removed and reinstalled the valve body to access the seals and the kickdown valve. I think it really was a lot of work, but it was disappointing to get it back with a flair. It was even worse to hear them say that I probably need a new transmission, since they just charged me almost $1000.00 for the work they did. Now I know they could have adjusted things to help me. They just didn’t know enough about the car. It seems that my 1995 E320 Special edition is just too old for the dealer to worry about.

Steve, while we are at this, could you tell me how to disable the cold delayed shifting thing that I hate? The guy above thinks it can be done. I will search the issue, but I trust you and would be thrilled if you can just tell me what to do. --- Woops, never mind Steve, I think I found my own answer with the search and I guess I will not do it. If you think the info below is wrong, I might reconsider.

Quote:

Originally Posted by Arthur Dalton

Delay shift basics........
The delay system is simply an ACTUATOR on the side of the trans that , when vac is supplied to its ELEMENT, mechanically changes the position of the shift cable.
This part of the system is not a Switch Over Valve or any other type of valve. It is a vac activated cable servo.
The activation of this cable actuator is controlled by the ECU sending an electrical sig to the SWITCH-OVER VALVE as determined by the ECU mapping. This allows engine vac flow to reach the tranny cable actuator through the SOV.
As soon as the ECU is satisfied , it stops the signal to the SOV ,which then closes and vac flow ceases to the actuator, allowing the cable to return to normal shift position...

...Many guys just put a BB in the line at the SOV and use a lower shift range when the car is warming up [ serving the same system purpose]. But, then the CE comes on and has to be erased. [ surpisingly, sometimes this can take a month] The reason for the BB line plug is to prevent a vac leak while the SOV is open.....

I did the search and it sounds like I could do it, but I would have issues with CE light, code #26, and even inspection. I think I will let it ride.

stevebfl · #21 04-14-2007, 04:14 PM

Getting rid of the cold running delay is nothing. The issue would be somehow fooling the controller into thinking it took place. I can think of at least one way but it would have ramifications to other processes and I'm not going to mention it.

One issue I might mention if you really wanted to screw with it. The vacuum box in the control pressure cable is adjustable. It could be adjusted to reduce the effect. I suppose if done in small steps over time one could find the threshold of failure that would be registered with a code. It easily could be that your situation is set way higher than need be. The spec is in service manuals and I don't recall seems like the shift has to occur above 1700rpms. It would be relatively easy to provide constant vacuum to the devise and make small adjustments while watching a tach till the threshols was reached. This would give the least intrusive shift acceptable.

As to the hard shifting point. The problem with getting the shift pressures too high are that reverse shift pressure is hugely different than forward gears and not exactly noticable as it goes up. The reverse pressure plate spring retainer has a bad habit of deflecting till the springs actually escape, detroying reverse gear and sometimes scattering pieces. Another problem with high shift pressure is the breaking of band actuator pistons and posibly bands themselves. I would suggest not going for the race trans shift kit effect, just get rid of the flare.

brewtoo · #22 04-14-2007, 07:26 PM

Quote:

Originally Posted by stevebfl

The spec is in service manuals and I don't recall seems like the shift has to occur above 1700rpms. It would be relatively easy to provide constant vacuum to the devise and make small adjustments while watching a tach till the threshols was reached. This would give the least intrusive shift acceptable.

I disabled this 'feature' on both our 124s.

It's been a while but if I remember right they both had to be taken up to 3000 RPMs for the first shift of the day. It was annoying and I did not like running a cold engine to 3000 right out of the gate.

ksing44 · #23 04-14-2007, 09:24 PM

Quote:

Originally Posted by stevebfl

As to the hard shifting point. The problem with getting the shift pressures too high are that reverse shift pressure is hugely different than forward gears and not exactly noticable as it goes up. The reverse pressure plate spring retainer has a bad habit of deflecting till the springs actually escape, detroying reverse gear and sometimes scattering pieces. Another problem with high shift pressure is the breaking of band actuator pistons and posibly bands themselves. I would suggest not going for the race trans shift kit effect, just get rid of the flare.

Enough said, I will not go for the race trans shift kit effect. I am going to be very happy to just not have a flair. I just took the car out again for a little test after not driving for about 8 hours. I had the shift delay, but no flair at all! I think I may really be totally cured this time.

I sure wish I lived in Gainesville FL so I could go to Continental Imports to have my car maintained. Then it really could be the last car I ever buy for me to drive. I don't know how long I am going to make it with my Indy and some of my own efforts. I sure would love to be driving my car 20 years from now, but I just don't know any more.

ksing44 · #24 04-14-2007, 09:31 PM

Quote:

Originally Posted by brewtoo

I disabled this 'feature' on both our 124s.

It's been a while but if I remember right they both had to be taken up to 3000 RPMs for the first shift of the day. It was annoying and I did not like running a cold engine to 3000 right out of the gate.

That seems to be how mine works. When the delay is affecting the shifts, the first shift affected, which is the shift from 2nd to 3rd gear, seems to happen at 3000rpms. I tend to avoid that rpm and just drive slower to warm up the car without going to 3000rpms. My way of thinking is that it would be better to spare my motor the 3000rpms when it is cold, rather than worrying about the converter for a minute or so. I guess we just have to chalk it up to being Eco-friendly, like the naturally degrading wiring harness.

Hey did you hear? I think I fixed the shift flair in my car!

brewtoo · #25 04-14-2007, 09:32 PM

Quote:

Originally Posted by ksing44

Hey did you hear? I think I fixed the shift flair in my car!

Yes, I heard! Good work!

ksing44 · #26 04-15-2007, 10:43 AM

Hi again Steve,

I hope you don’t mind if I ask you just a couple more questions on the same subject.

First let me tell you that it was a chilly morning here in the Northeast so I had a chance to test drive the car this morning in a situation that would have previously been filled with shift flairs. I had absolutely no flairs! The shifts were nice and firm at all speeds with varying degrees of acceleration.

My last questions:
1. Considering what you wrote about the risks of going for the race shift kit effect, do you think it would be worth it for me to back off on my one-turn adjustment, to say one-half-turn, to minimize the wear and tear on my transmission? If I had to guess, I would say it must be a balancing act between wear on the bands/clutches vs. “breaking of band actuator pistons and possibly bands”. I guess what I am asking is, based on your experience, what is more likely to end the serviceable life of my transmission.

2. Considering that I probably do have some wear in the transmission that lead me to have to make the vacuum modulator adjustment, are you willing to give an estimate about how long this adjustment will give me before I have to replace the transmission. Just in case you are willing to make a prediction based on my situation, I can tell you that I currently have 102K miles on my 1995 E320 and my short commute puts me in a situation where I tend to make short trips in the car.

Just one final note, I think this is a pretty common problem for many so perhaps your expertise and my trial error adjustments detailed in this thread will become a definitive source on the subject.

I hope your business is absolutely thriving in Florida.

stevebfl · #27 04-15-2007, 10:55 AM

If you haven't guessed, the balancing act you speak of is dealt with in concept by actually using precise setting to the pressures involved. Many techs who have done this a lot have grown a feel for the edges. In general I'd say your long term risk of incapacitating failure is more from over pressure. A broken band or burst rev spring pack is an end game.

I feel pretty confident though that the pressures that cause these issues are significantly above your situation. I had a 300SD recently that broke a band. He had called me a few months prior about his harsh shifts. A diesel with a vacuum problem cause outragiously more pressure to the shift components. So we rebuilt it and then fixed his vacuum problem.

Some of the flare issue can be brought into any trans. I think you have a situation I wouldn't worry about. Your problem was mostly brought on by the misadjustment of the control pressure cabble and I'll wager your are still high on your delayed shift which has agrevated the issue.

Petes · #28 12-07-2008, 12:17 AM

Could one of you tell me the location of the modulator valve on a 94 E320 so I can make this adjustment?

hamrt · #29 09-17-2009, 10:56 AM

I'm not understanding what you mean be a shift "flair". I have a 1991 300CE that is not shifting up into 4th. Is that what your car is doing or did I miss something? And what is the deal that german cars don't start in 1st gear? I have a 2000 BMW that starts in 1st but at it's own discretion, starts in 2nd. I put it in Sport Mode and it will start in 1st everytime. Strange, a car with a mind of it's own!

But anyway, back to Mercedes... Now, if there is something wrong INSIDE the transmission, would this cause some of these same problems. I had a '97 GMC truck that blew a servo inside and I lost 1st, 4th and reverse because they were all controled by that internal servo. My car (the Mercedes) has no slippage or clunking in the tranny, it just won't shift. Am I to understand that if the bowden or pressure cable is too tight, it might start in 1st gear and not go past 3rd? The shift quality is okay, smooth, that is, but does seem to be a bit late at moderate throttle positions. Tranny has always been serviced and has 112,000 miles.

I'm not an automatic tranny expert, I only know the basics but I am hoping with help I can figure this out.

P.S. A picture of a typical bowden cable arrangement at the engine and tranny on a late 80s/early 90s 300 6cyl would be helpful.

ksing44 · #30 09-17-2009, 12:55 PM

When I was playing with my Bowden cable I did tighten to a point where it basically would not upshift to 4th gear, but it was similarly delayed shifting into every gear. The tight cable made my car think I had the throttle floored, even when I was only giving a little gas.

The "flair" is a kind of slipping as it shifts to the next gear. As a result of the slipping in the transmission the engine rpms go up, or flair, in between the shift.

Bye the way, just last week I turned the modulator back, i.e., counterclockwise, by a half turn. I was worried that all the shifts were just a little too firm. I do have the slightest flair from 3rd to 4th, sometimes, but the rest of the shifts are just about right. I think I am going to stay with the half turn change. Last week they also dicsovered a leak in my evaporator, so I hoping the transmision hangs in there for another year or two.