300E Transmission problems

[Jordan_3202000]

My 1989 300E seems to be having transmission problems, a few times when accelerating, the transmission does not upshift as it should, and as a resuld revvs up very high, and then slams very hard into the next gear, i checked the ATF, and the fluid level seems fine, any idea what could be wrong?

[jtripp]

This condition probably had a sudden onset. Check all of the small diameter vacuum lines for breaks or being disconnected. Also check the rubber molded ends for splits or being disconnected. I accidentally broke a vacuum line while changing the belt tensioner on my'95 S350. The symptoms were the same as you stated. The break may not be visible if the vacuum line is covered with a plastic sleeve. The nylon vacuum lines get very brittle from age and especially the heat in the engine compartment.

[Robert Goodwin]

An additional thing to look at is the vacuum modulator itself. Carefully pull the plastic line off the modlator. If it is wet with transmission fluid, the diaphram is punctured and would give the same results. You could make a final check with a vacuum pumpif desired.

[Jordan_3202000]

Thanks for all your help, i'll look into those things you suggested

[Jordan_3202000]

I found the problem, as you both had mentioned, it seems one of the vacum lines had developed a leak, i replaced it and now it works perfectly. thanks for all your help

[iworkit]

what was your problem and were did you find it I have the same problem I really need help :(

[docjbr]

I don't know if we have the same problem exactly.

When I step on the gas (about 50-75% pressure) byt the time it revs and is SUPPOSED to shift into 2nd gear, it overrevs (slipping?) before heading into 2nd gear. Between 2nd-3rd-4th, I've heard no problems at all.

When I step on the gas in a very delicate manner (knowing that it overrevs) somehow, it doesn't overrev and goes in smoothly. Anyone know if I might have the same problems too? Thanks!

Jay

[Robert Goodwin]

A little more info could be helpful.

If this condition came on all at once, I would say that someone was probably working on the linkage, especially the cable to the transmission.

That cable determines when the transmission will shift.

What is the background on the problem?

[docjbr]

Hmmm.. Wouldn't know about the background. I bought this car a couple of weeks ago, didn't notice it that much, just thought I was pressing on the gas too much. Only happens when I come from a full stop (Ummm, I don't know if thats an obvious point, problem being from 1st to 2nd gear only) Other than that, everything else shifts fine.

[iworkit]

that happened to me at first until it finally stop to shift.
Al

[Robert Goodwin]

Lets go over this again.

First, you have a 722.XXX transmission. It is a 4 speed. Normal automatic shifting starts out in 2nd, then up shifts to 3rd, then 4th. Getting it into first gear, as I recall, requires a forced downshift. At some point, Mercedes modified this transmission so that it would remain in 2nd for 60-80 seconds in order for the catalytic converter to warm up. Don't know for sure if your year is effected, but sounds like it might be.



After reading this, do you still believe there is a problem?

[iworkit]

I have a 1991 300E I had this problem a while ago until it started to get worst and now I don't know were to start. yes I still have the problem.
Al

[Robert Goodwin]

Doc:

Do you still have a problem based on my last post?

Have you considered changing the fluid and filter (including torque converter)?

Al:

When is the last time the fluid (including torque converter) and filter were changed? Many times, this will clear up a lot of problems.

[iworkit]

haven't done that in a long time I guess can you tell me were i can find these. this would be a great help I don't want to cause any other problem. is it the black box under the transmission? thank you
Al

[iworkit]

what about the torque converter

Al

[bill streep]

If the transmission fluid/filter hasn't been changed recently, do this first. It's not a DIFFICULT job, but it can be messy. Do a search, you'll find out how to do it, and to drain the torque converter.

[docjbr]

Okay, will try and change the transmission fluid and the filter. Was planning to change all fluids in the car since i got it last week (i.e. power steering fluid, brake fluid, engine oil - did I miss anything?)

Unfortunately, I don't think I can do it myself or I'd have to wait till around 1st week of July. I'm taking the first part of my board exams, so I can't really afford to spend some time on the car (I only allow myself to surf the net during my 1 hour lunch break, hehe)

Thanks guys!

[Robert Goodwin]

Don't forget the often overlooked filter in the power steering unit.

[iworkit]

what is in the torque converter ATF right? I know it sounds dumb but I need to know I don't want to cause any problems.
Al

[docjbr]

Don't forget the often overlooked filter in the power steering unit.

Check.

Things to do:
1. Change oil (synthetic)
2. Oil filter
3. Brake fluid
4. Power steering fluid
5. Power steering filter
6. Coolant
7. Automatic Transmission fluid
8. Tune up
9. Alignment

Anything I miss?

[Robert Goodwin]

FOR IWORKIT:

Torque converter is drained seperately through its own drain plug.

It is refilled from the transmission.

In short, 2 ways out, one way in.

[Robert Goodwin]

For docjbr:

You will need a transmiission filter. Kits from McParts include the pan gasket as well.

Not so fast on changing the brake fluid unless you have a pressure bleeder. See your Repair Manual for instructions.

Don't have the manual? Buy one. I estimate the work on your list will cost between $500 and $1,000, depending on where you take it.

You should be able to recoup the cost of the manual (CD) in less than an hour of do-it-yourself time.

See the thread in this forum: How To Repair Everything On Your Mercedes

[iworkit]

I forget to mention that I had my engine replace last summer didn't they have to drain all the ATF? Could this still happen if the filter isn't clean?
Al

[Robert Goodwin]

Al,

I'm not sure I understand your question.

You had the engine changed out. That could entail draining the motor oil from the engine.

Why would they have drained the automatic transmission fluid from the transmission/torque converter unless you asked them to?

Your option here is to take the car to a shop. A transmission shop will drain the fluid, drop the pan, remove the filter, say to you, tsk, tsk, your transmission needs to be rebuilt, $2,000 please.

Your other option is to change the fluid and filter and see if that fixes it or changes the operation.

[bill streep]

Al,

Listen to Robert.

It's unlikely that they would change the ATF. In any event, if they did drain it or some of it, it's also unlikely that they changed the filter. Changing the ATF will take about an hour under the car, it will be a bit messy, it will cost you less than $100 including the kit, even if you use synthetic ATF.

[flyingfrankie]

you could find a lot of helpful pictures out of the books and cd rom's. transmission fluid should be replaced at least every 24 mo incl filter and the torque convertor. for the last one you'll have to rotate the engine until you'll se the little drain plug in the converter opening. make sure you have the right size and quality allan bit and insert it all the way if not you might strip the inside of the drain nut . all very simple and easy. for vacuum leak testing spend 30 bucks on a mighty vac pump .
have fun.

[loclark757]

My transmission is leaking the car hasn't been turned on in about a month or two and Im about to do a tune up as well as new head gasket.

What's entailed on a transmission tune up?

?-New seal, hoses, change fluid obviously...What tools do I need and why can't I find info in the FSM about the transmission...