W140 300SEL - Corps

[Xulfiqar]

this is also the repair procedure when removing a corolla evaporator (all the later models starting from the 120 chassis) - the evap in a corolla is in the plastic hvac box - in this mercedes its in the large cavity you see in the middle and is about the size of a mitsubishi Mr slim 1 ton split unit evaporator. - that cavity becomes part of the HVAC unit once its assembled.

The W124 is similar, the W210 is like the corolla - the evap in a box - but its pretty big too like this one.

The job is not too bad - its just 4 times the parts that you see in a econo car and its beautifully laid out, its just time consuming. - to make it easy I recommend to raise the car on jacks or ramps so you can be on your knees outside the car and reach in (for a 6'5" person like me at least) - I dont like to become a lizard under a dashboard disconnecting stuff.

[Xulfiqar]

true, I dont know why people think its something like alien eggs.

[corps]

But... I'm missing an EGAS unit (got stolen) in the app box. What?

Also, sometimes my reverse jerks. Checked the B3 piston and it seems to be on-point. Occasionally the car would engage the reverse but lock itself out like won't go forward or backwards on an incline and/or decline. I can crank and start it up with the selector in Reverse as well. I'm guessing something has gone kaput with the safety switch(?)

Edit: The transmission was also brutally over-filled. Need to extract some of it out. It is all the way over the marking by atleast 4cm.

In comparison to the 300SEL, my S320L is a gem. May look slightly old and not my choice of color but it is spot-on in terms of up-keep.

[Xulfiqar]

this would have an old hydraulic 722.3 transmission, the reverse on those is lazy when its best.

btw - the fill line when dead cold for ATF is not the low point on the stick, On the 722.3 its 5mm below it. The safety switch will usually be ok, but the bushings on the selector lever and manual valve shaft on the gearbox will be shot - which will make this stupid start in R etc situation.

The trans seems to be in need of an overhaul. Sonnax and superior have some really nice kits to fix these problems that arise as these transmissions age. Does it shift crisp or super slushy? - This old gearbox takes regular cheap ATF dexiii - changed every 40,000 kms - dont use any friction modified stuff.

[corps]

@Xulfiqar
Something is stuck in there. Ok, here's the recent update. When I put it in reverse the RPMs drop instantly (engages), I accelerate it goes back almost instantly as if everything is fine but then it halts as if I put it into Park while the car is moving. Then it rocks back and forth like it does if in Park. After that it gains RPM but is obviously stuck. Is there any possibilty the tranny is not getting out of Park even in reverse? Sometimes it gets out of stuck zone for a while and would go 50m or so with great power and no slipping but then BAAAM stuck rock back and forth on a lock like I just put it in Park by force.

So as I understand the B3 brakes apply in reverse and then the K2 engages? I need to understand this. Unfortunately I have not been into transaxles.

For anyone else every reading this in PK and for PW in general here are some useful PDFs for 722.3/4/5 autoboxes (Mention how it helped you if it ever did):
Mercedes 722.4 adjustment guide.pdf (1.5 MB)
722.3, 722.4_part2of2.pdf (1.2 MB)
722.3, 722.4_part1of2.pdf (973.9 KB)

[Xulfiqar]

the parking mechanism has nothing to do with clutches, its the parking pawl in the tail end of the transmission that holds/locks the car in park.

replace the bushings on the select lever and manual valve in the transmission and then check the rod for misadjustment - You are seeing "ustaad shaagird" problem here.

[Xulfiqar]

btw - the service manuals for these hydraulic gearboxes were never translated into english, all of them are in german. And all of them are unique to themselves. - I had them in book form and it became tiring really quickly to type german on a computer to see the translation.

So when rebuilding - pay extra extra close attention to how stuff is coming out, specially in the valve body.

[corps]

You're right, this box is rebuilt by some lunatic with local made seals and stuff. It has more leaks than I can imagine. Every damn seal is leaking. I'm taking this thing apart whatever. Local mechanics created a lemon out of this otherwise great W140. Btw - there is a YT channel named AndyP Mercedes if someone needs a videolog of a rebuild. Love that guy, he speaks russian in some videos though and my russian is only marginally good .

And yes the shifts are slushy, almost like the car hit neutral between shifts.

[corps]

I will video log everything with two cameras on tri-pods because otherwise I will be lost.

[Xulfiqar]

you can tighten them up with the modulator adjustment and the bowden cable adjustment.

[hash4u]

apologies for interruption
how many miles does this S class have ? more then 100,000 miles ?

[corps]

@hash4u 200,000'miles' but the silver has 210,000 miles and is iron-clad. All about up-keep. These autoboxes were sealed for life.

[Xulfiqar]

these autoboxes were not filled for life, the fill for life crap was only written for US market cars with the 722.6 gearbox. - The rest of the world had 40,000 miles (65000 kms) oil service for the 722.6 (5 spd auto) and the usual 25000 miles (40,000 kms) for the old full hydraulic ones (aka 4 spd)

[corps]

Sir wasn't 722.5 also sealed for life in NA?

[Xulfiqar]

the 722.5 is a 722.3 hydraulic with a tacked on overdrive external unit - and its not sealed for life - it requires change of oil every 25K miles.

funny thing on these is the little computer that makes it go into 5th. its a pwm command to slowly engage it - infact disengage and hold it till required.

when it goes bad the shifts go like 1-2-3-5