Transmission part 1994 E420 - PeachParts Mercedes-Benz Forum

DRICHFL · #1 08-07-2006, 01:27 PM

What is the plastic part?
Okay, here is what happen. I notice over the last couple of days that my 94 E420 was not shifting gears as smoothly as it usually does. It would hold the 1st gear, then shift to 2nd gear and hold, then shift to 3rd gear and operate correctly around 55-65 MPH. If I floor the gas pedal at high speeds the car begin to hesitate as if the drive belt was slipping or as if the transmission was slipping in and out of gear.

I decided to check my transmission fluid and it was okay and in good shape. Got under the chassis and notice 2 things. The first, was that it was wet around the starter lockout switch/safety neutral switch and that there was a hose above leaking fluid in which I determine to be A/C water discard. The water has been leaking on the metel rod that attaches to the top of the starter lockout switch/safety neutral switch which has cause surface rust on the metel rod. The second, was that there was a plastic ring part that was attach to the metel rod in which I feel has something to do with keeping the metel rod secure to the starter lockout switch.

Can someone give me some feedback on this plastic ring piece.

The first photo is of the hose that is dripping water. Is there suppose to be something attach to stop water from leaking on to the starter lockout switch.

The second and third photo is of the plastic ring piece attach to the metel rod. What is this plastic ring called. Thanks for any feedback on this problem.

Gilly · #2 08-07-2006, 05:17 PM

I'll try to at least get the ball rolling here for you.
Never noticed the AC water dripping on to the switch. The pic is kind of small but yes I'd say there should be a small rubber piece attached to what looks like a short, hard plastic tube.
The rest of it is a bit confusing, here's what I think you mean: On the switch, there is a lever which changes the gear you are in. At the top of that lever is the shift rod, this is what seems to be rusty on your car. The hole in the lever for the shift rod is a white plastic bushing, that keeps the rod from wiggling too much, like a spacer. These do tend to wear out over time. When it wears out the shifter will make a metallic rattling sort of noise when shifting to different gears (park to drive for example). The part is called the shift lever bushing. Helps?
Gilly

DRICHFL · #3 08-09-2006, 03:50 AM

Where is the vacuum modulator valve located on my transmission? Does it play a big part in transmission shifting gears?

I truly feel that my transmission is in good shape. So I am checking the Bowden /throttle cable and vacuum lines.

In addition, Gilly the white plastic bushing is it called shift linkage bushing? That shift linkage bushing doesn't seem to look like the one I have on my trans. Is it an upgrade design.

Gilly · #4 08-09-2006, 11:27 AM

I think I am looking at the same thing you are. Yes, yours looks updated as in "broken in two" being an upgrade (J/K). The side on the very end of the rod (by the retaining clip) is still there, but the outer half seems broken off, I think I see it further up the rod. If you feel up to it, the absolutely easiest way to put the new bushing on it to simply remove the lever and do it off the car. You need to put it in boiling water to soften it up, then will pop right in. Wait for it to cool enough to touch without scalding yourself obviously.
Vacuum modulator, ahead of the shift lever (on the trans) fairly low, maybe the same height as the pivot of the lever. Has a single vacuum line connected to it. Has a rubber cap over it, under this cap is a "T" piece that pulls out and that adjusts it. It affects how hard or soft the shifts are. ASK about it if you intend on adjusting it, don't just start fiddling with it.
Other major adjustment point is referred to as the TV cable (TV=throttle valve), this is adjusted at the throttle linkage under the hood, it more affects WHEN the transmission shifts, not the hard or softness of the shift.
Gilly

DRICHFL · #5 08-09-2006, 10:17 PM

Gilly, I track the vacuum hose that runs from the intake manifold to the transmission. I assume that it is connected to the vacuum modulator. What must I do in order to get the transmission to shift smoothly again. I earlier check the Bowden cable and also the adjustable connecting rod. Both the cable and rod are in the proper position. In addition, the throttle control linkage did not need any adjustment because the plastic tips indicators both line up.

The first photo is the Vacuum Modulator, second is the bushing are these correct for my e420.

Gilly · #6 08-10-2006, 07:53 AM

The bushings do not look correct to me, maybe I can find a pic at Fastlane, which is who i would recommend using for parts if you are going on-line to buy things.
The vacuum modulator is color coded. The hard plastic outer part is found in a few different colors, the one in the pic for example is black. If the existing one is black then it's the correct one. The basic shape of this one I think is correct. Start the engine and pull the line off the modulator and make sure there is vacuum present.
Gilly

Gilly · #7 08-10-2006, 08:05 AM

I think it's supposed to be this type:
http://catalog.eautopartscatalog.com/mercedesshop/sophio/quote.jsp?clientid=catalog.mercedesshop&cookieid=1VC0GXUSV1VC0H5JOA&baseurl=http://catalog.peachparts.com/&partner=mercedesshop&year=1988&product=J4070-44817&application=000046642
Not 100% sure though. The type you show I don't see what holds it in place, unless there is a slight outer groove. The one I link you to there is a deep outer groove that holds it on to the lever.
(I used a 1988 300E as an example to try finding the part I thought you need, just so you know why it's showing the part for a 300E)
Gilly

DRICHFL · #8 08-10-2006, 12:29 PM

That photo looks more like the bushing I have that is broken. However, if vacuum modulator is in need of replacing is there any pitfalls I should worry about. I will most likely order the part today. In addition, if there is vacuum present from the vacuum line running from the intake manifold is it recommend to just replace the modulator or adjust it. How do I adjust/test the modulator to see if it is the problem. Thanks

Gilly · #9 08-10-2006, 04:40 PM

I'd try adjusting it first. You remove the rubber cab, and you'll see a series of slots cut into an outer ring(the ring the rubber cap is attached too) and you will also notice a piece of metal between 2 opposing slots. This is the "key" you use to adjust the modulator. Pull the key out enough to clear the slots and it is turned to adjust the shift harsh or softness. Turning the key clockwise increases the harsh or hardness of the shift, counter clockwise softens the shift. DON'T let the shift get to soft or the transmission will flare and wear out quickly, the shift should feel a bit firm as compared to most automatics, this increases the service life. Try adjusting a couple slots at a time only, no great changes. Make sure the engine is warmed up when you do this.
Gilly

DRICHFL · #10 08-14-2006, 06:55 AM

Gilly, I purchase the shift linkage bushing and install it on the metel rod. Thanks for the suggestion to boil the water and drop the bushing into the water to soften the plastic. It was nearly impossible to get the bushing in place without heating it up to make it soft.

In addition, while I was installing the bushing I decided to adjust the transmission vacuum modulator. The vacuum modulator is located in front of the starter lockout/safety neutral switch. I discover that the vacuum modulator on this transmission has a white plastic cap on it. I could not find the things you describe in the earlier post. Since the vacuum modulator has a white plastic cap attack to it I am not sure how to adjust it. I played around with the idea of attempting to rotate the white plastic cap counter-clockwise. Is this the proper way to adjust this vacuum modulator.

Last, I plan to check all vacuum lines in the engine compartment to make sure they are holding vacuum. Is there a certain among of pressure the the lines should hold. Thanks in advance all comments are welcome.

Gilly · #11 08-14-2006, 04:30 PM

Can you get a pic up of the vacuum modulator? I can see the edge of it in one of the pics, I'd like a shot of the whole thing (at an angle is fine of course)
Gilly

DRICHFL · #12 08-15-2006, 02:20 PM

Here are a few more photo....

You will notice on the second photo the vacuum hose attach to the modulator. It can be trace back up to the intake manifold as you can see in the last photo.

DRICHFL · #13 08-15-2006, 02:25 PM

There is another vacuum hose that is attach to the opposite side of the transmission. I think the vacuum hose is attach to some type of pump that is mounted on the transmission. The vacuum hose can be trace back up to some type of switch over valve. Here a photo of the other vacuum hose which is running from the switch over valve to the transmission.

Gilly · #14 08-15-2006, 04:01 PM

The one on the opposite side I believe is the upshift delay solenoid. This delays upshift when the engine is cold to help warm up the engine and specifically the catalytic converter faster. POSSIBLY this is why you have these delayed upshifts, does it do this ALL the time or just for the first 5 or so minutes with a cold engine (in the morning for example)? If it does it all the time the fault could be with the throttle valve assembly (which includes the upshift delay solenoid), I've seen this before. Not sure why I'm not seeing the adjuster on the vacuum modulator, maybe they deleted the adjuster and I never realized it.
The upshift delay solenoid should also have the cable running to it from the throttle linkage as well as the vacuum hose. I've never had a problem with the switchover valve for the upshift delay, usually the part on the transmission (the solenoid itself) sticks or stops working, but the other parts are a possiblity too, or the throttle valve cable is out of adjustment.
Gilly

DRICHFL · #15 08-15-2006, 07:13 PM

I recently made and attempt to rotate the white plastic cap on the vacuum modulator. The plastic cap apears to have a lever molded into the cap. I turn the cap counter clockwise then I drove the car. The transmission shift a little smother but delayed shifting from 2nd to 3rd. Once it got into 3rd it immediately shifted into 4th and operated correctly while traveling 55mph. Before rotating the plastic cap, the transmission would delayed shifting even longer in 2nd up to 4500 Rpm then shift. After rotating cap it delayed shifting between 3000-4000.

Fars as the climate, the transmission does the samething whether the engine is hot or cold. I am still brainstorming my problem.

How do I know if the upshift delay solenoid not working properly? On the transmission located on the passagers side is the black vacuum hose is attach to a blue object which I assume is a pump. Am I correct? I will post a photo of this object/pump sometime tommorow. It is kinda hard to get to without dropping the trans. How do I know if object/pump is not opperating properly? Thanks