Hello,
please help me with this problem, because I am desperate and cant figure it out even after I checked valvebody control valves (17,18,19 and others) which actually control 1-2 upshift.

Here is a link to my thread on benzworld,where I expain everything about the situation:
600 SEC transmission starts in 1st and skips 2nd gear(acts like there is no 2nd gear) - Mercedes-Benz Forum

thanks for help

bump,

I am sure someone knows whats wrong, I searched the forum but no solution was ever posted to this problem even though there were very similar problems discussed.

Please help me with this, as it drives me crazy and makes me not really enjoy the ride

A broken spring under the B1 shift valve will allow the valve to remain in the "pressure dump" position. In this position there is a very slight amount of flow to the B1 piston, and a very slight band application, all consistent with what you are experiencing. Spring breakage will produce the symptom instantly.
You will need an exploded diagram of the valve body parts to locate, and remove the valve and spring.

Hi,
Thank you very much for your precise answer, It is what I expected to hear (something new and something professional), I have all the data needed like manuals. Do you mean the yellow one (accumulator)? or the one with part number 1242700035?

thanks

Or there is valve 10 which is called "b1 shift valve" to which I wasnt able to get to because of a screw that got damaged.

I'm not looking at the same diagrams as you are (no colors or part#s), however the valve in question is not an accumulator. It is called "B1 shift valve". It controls oil flow to and from the B1 piston.

then is its probably the number 10 in the ATSG and here it is also number 10:
722.303 in bits photo shoot

Now I dont know how to get to that valve cause the aluminum screw got badly damaged as it held the position and the screwdriver messed it up to the point it cant be moved a bit by a screwdriver. Any suggestion on how to get trhough this? And what to do when the spring is broken? Do they still sell them and what part number is it? Maybe I need to get another valvebody . Are they interchangeble with v8 valvebodies? (except v8 w124 I know its 1gs)

Sorry for my engish Im from Slovakia

thanks

In addition to #10, also some attention should be directed to #17, 18, 19, 39, and 39 (all in Stretch's pictures). They are also involved in applying the B1 piston.

I believe all the V8 valve bodies can be used, but, some of the springs are very likely application specific.

I had noted your location in another thread; your use of English is excellent.

I personally checked the function of the 17,18,19 and 38, 39 valves, and they work but how unlucky I got with the number 10 , I tried to get to to it, but the screw stopped me, so I told to myself, that what I already did was probably enough to eliminate my shifting problem and here we go again...

I need to find another valvebody but here in europe people dont really sell valvebodies, they dont usually let you have it without buying enitre transmission. I understand them because they wouldnt be able to sell the transmission that easily. But still sometimes they are selling it rather cheap so maybe I will be able to give them a reasonable offer. How I wish I found someone with a damaged transmission to part it out.

thanks

anticore,

I recently experienced this skipping 2nd in my car ('95 E420). Actually, it would rev high in first, then hit 2nd for a very brief moment then go to third.

I replaced all the rubber elbow fittings for the various vacuum lines under the hood just because they seemed loose. This would up fixing the problem completely!

Hi,
possibly too much vacuum can cause flaring, this can be regulated by the vacuum modulator ( I had flaring between 2-3 shift last year, fixed it by reducing vacuum with modulator), now I drive without vacuum (just to test it) connected so there shouldnt be any vacuum reducing pressure I guess. But then again there is no 2nd gear for me, not even manualy, so I guess its some sort of command problem. I am working on acquiring another valvebody and it seems I may have found somebody to sell me the VB for not so much "knock knock", but its gonna take a month (until the seller comes home) and then I will install it and share the results. I may even fix the old valvebody and then sell it to someone in my kind of situation if I find the stuck valve.