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Discussion Starter #1 (Edited)
this one is tough... Here is the deal:

car is 94 mercedes c220 165 400 miles with the vacuum operated tranny.
in the morning when the engine is cold the transmission shifts late as it is supposed to and veeeery hard (95% of the time). After about 4-5 miles it warms up and does not shift late anymore but still shifts hard (95% of the time) but it is softer then when it has not warmed up.
Sometimes it will shift very smooth just like it is supposed to but that is very rare nowadays. sometimes even when it has warmed up it will delay shift and will shift very hard. when it shifts smooth it never delays before shifting.
Also shift between 3 and 4 seem to be the harshest and most delayed.
The hard shift I describe as if somebody hit my car in the back, almost as if I have disconnected the vacuum line supplying the tranny.
Also one other thing (that might be normal) is that If I want the car to upshift I have to let my foot almost completely of the gas. Even with 1/6 gas it will not upshift or at least not before it gets to 3000-4000 rpm.

So here i have 3 pictures. Two of them show my tranny oil level (which seems to be very high) but then again the oil level has been like that for the last 30 000 miles or more and it was shifting ok until 1-2 months ago when it started getting worse and worse also the oil looks clean.

since I personaly think that it has something to do with the upshift delay or vacuum I did a vacuum test and it is on the 3rd picture. The vacuum level seems low and I am pretty sure there are no leaks since while I was taking the reading I disconnected every line that I found connected to the manifold and plugged the hole and this did not get it up.
The other thing I am suspecting is the transmission modulator which I am planning to adjust counter clockwise to soften the shifts but I do not know if I can reach it without removing anything.

So please let me know what you think guys and if somebody knows If I could temporary bypass the upshift delay or at least how does it function so I can investigate that part too.
Btw the transmission oil reading was taken after a 30-40 mile drive. engine does warm up to about 82-83C.

P.S Here is two great PDFs that I found about this transmission I think it is 722.4:
http://avtopedia.ru/akpp/722-3 722-4.pdf
http://transtec.com/tech_insert/94642.pdf
 

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Modulator adjustment

Your modulator pressure needs to be checked. Read all about my experiances with this problem earlier this year complete with modulator adjustment procedure.

You can probably reduce your pressure just by turning the cap. The stock modulators have an adjuster built in. The one in my Thread is a replacement unit.

You may disconnect your upshift controller by either unplugging the vacuum hose from the relay or electrically unplugging it. It's located under the cover under the hood passenger side, next to the duo valve. Your car will probably throw a code if you unhook it.

You need to test the manifold vacuum at the point where it goes out to the Modulator. Look in between the intake tubes and you will find the line that goes to the Modulator. Make sure you have between 11-15 lbs. at the Modulator as well. AFTER you check the Vacuum Pressure to the Modulator then adjust the pressure down a small amount if you still need to. I really reccomend using a gauge as I did in the Thread. It is supposed to be a very fine adjustment. It made a HUGE differance to our Tranny, as you will read in the Thread.

http://www.benzworld.org/forums/w202-c-class/1380730-transmission-lunching.html

Good Luck!:thumbsup:

C as in 220
 

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Discussion Starter #3
Thanks man! I actually read your post just 2 hours ago and was messing with the car until now and I think I got it! :)))

by the way I did a vacuum test at the transmission vac line too and it was the same reading but I forgot to say that in my post.

First I did try to just move the cap without removing it (I read it compensates for 0,2 bar) in this pdf: http://www.w124performance.com/docs/mb/other/tranny_722_repair.pdf

but I did not notice any change. Then I broke the cap ofcourse and got it removed (it is only cracked I am still using it). And turned the thing 360 deg ccw and noticed a very slight difference. Then I turned it another 720 deg ccw (i read one turn is 0,7bar I figure one turn is 360 deg) and it was getting smoother but still lagged on the upshift so I figure I will make one full turn on the cable clockwise to loosen the pressure to get earlyer shifts. Did that and it started shifting too early and flaring so then I put the modulator almost back to stock - only 180 deg CCW and drove again and no flare and shifts on time and soft (not banging the drive shift in the diff like before). So I think I got it :) I will do some more test driving and see what happens.
Your post was very helpful I will get that gauge in the near future and I do have the banjo fittings so I will make a device like yours because I have been having some issues with my 83 300D turbo too.

I am very happy now. I love the forum it is very helpful.

How about my oil level in the transmission? Is it ok if I just leave it like that? It has been like that for at least 30 000 miles so it should go more with no problem right?
 

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Tranny Fluid level

I would remove a cup or so at a time and recheck it when hot. I had to remove a cup and a half when I changed my fluid and the stick looked about like that. The older Trannies like yours are NOT as critical as the 5-speeds about being slightly overfilled however. I removed my extra by using clear aquarium air hose and a small bottle with measurement marks on the side. A long enough hose and you can easily siphon out the extra into a small bottle.

I'm glad to hear you got it tweeked into line. I'll bet your neck is a bit sore tomorrow from getting under there so many times.:eek:

Good luck!:thumbsup:

C as in 220
 

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Well the manual says to do a transmission fluid and filter change every 48,000 kilometers which is about 30,000 ,miles,, So If I were you I would do a Tranny fluid and filter change, as soon as possible.
 

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I have a 1996 C220 with 114000 on it and I have been having the same troubles you describe. In looking at it, the vacuum hose that connects to the modulation valve is connected at the valve but is not connected above and I do not see the obvious connection place. I have looked at the vaccum schematic pdf that is on the internet but it is not real clear where it is supposed to connect to at the engine...

Any suggestions?
 

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95 220 vac diagram under hood. There is second vac house on pass. side. As you can see on diagram tr. modulator vac hose is attached to intake manifold very close to cyl. head. Good luck!
Today I replaced filter, if it will not fix hard shifting, I'll be checking vac hoses and adjustments tomorrow. Thanks for adjustment and repair info.
 

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