So I have now removed and dismantled the valve body from the transmission, after having had to drill and extract one stubborn bolt from the 10 holding the body. As the Tork heads of a couple others are slightly damaged, to be on the safe side I ordered ten new bolts at the local MB dealer.

To finish the reconditioning, I'm just waiting for the two Sonnax kits Overlap Control Valve Sleeve and Regulating Pressure Control Valve Spring which are on the way over from the USA.

Regarding the ATF, what is the easiest method to flush out ALL the fluid (torque convertor and pipes to/from oil cooler, etc.) from the transmission? I have plenty of Fuchs Titan 3353 Dexron III in reserve.

Do not do a flush/exchange to any 722.6 from the 90's as the K2 bearing is not a ball bearing, but a copper clad bushing, and you are liable to wick-off the lubricant from the bushing, and cause a K2 failure which leads to all planetary gear destruction as like in post 4 from the link below...

722.6 slip and shudder in D and R, rattly noise in N and P problem on 1998 S420. - Mercedes-Benz Forum

Martin

While a failed K2 bushing can cause thrust washers to come apart allowing needle bearings to fall to the planetary gears, it isn't likely that draining fluid will cause this type of failure. It is true that in 99 ish a needle bearing and teflon seal was used to combat long term wear, but it has noting to do with surviving a fluid change. Even if one is slow to add fluid with the engine running, the K2 bushing sees about zero load when the car is sitting so even a drop of oil will keep it lubed.

As the K2 bushing wears, planetary needle bearing thrust washers are no longer loaded flat, the are cyclically point loaded. This causes the race to spin in the housing wearing the aluminum housing. The result is increased end play that coupled with needle bearing cage wear allows needles to fall into the planetary gears. When the K2 was upgraded to a needle bearing, MB also put ears on the thrust washer races to prevent them from spinning.

In fact, if you order thrust washers from MB and have a early trans, you will get washers with ears. It is possible to retro fit, just grind pockets the ears.

Last year my 97 C280 with 161K miles started to occasionally get a singing / siren sound. ( I've heard it before on a domestic planetary style truck transfer case ) Not wanting to take a chance on more damage, I pulled and rebuilt the trans. The K2 bushing had just enough wear to allow the planetary to run off center causing noise. Given the trans went 161 K on a bushing I installed a replacement bushing and upgraded trust washers to the eared type. After 5 K the noise has not reappeared.

When I get 90's 722.6 cars for tranny work. I never rebuild them as they are, but swap the internals with a non-interlock(the ones with the revised bearing shafts). You are a lucky man for not having total destruction, but the owners of C-Class are super rare to to do a tranny rebuild, yet on a S or E class cars when it happens it is in a matter of 50 to 100 miles from some major fluid service, and it is always total destruction.

The change occurred for the ball bearing for the most part on +2000 cars, but this true for W210, W215, W208, W220. The R129 did not see the change even though the model went to 2002.

The bushing cars have a interlock cable on the left rear of the transmission to release it from park. The ball bearing cars have no interlock cable, but the shifter has a locking solenoid built in to the shifter

It is not a matter of swapping the bushing for the bearings as the internal shafts are different. The one way bearings(sprags) increased in count. The rear sprag went from having a bushing to having a big ball bearing.

96-97 valve body are only compatible with each other, yet 98-99 valve body is backwards compatible with the non-interlock trannies, +2000 valve bodies have been totally redesigned, and no more pressure regulation spring like in the 90's 722.6

In one of my 98 W140 S500 I have a 2003 W220 S430 internals in the 722.6 interlock transmission.

Martin

On my C280 , I had been planning on doing a trans rebuild even before it started to make noise. The thrust washers / bearings / planetary housing never started to wear so the thrust bearing needles never fell out. Given the cars are light and have modest engines, trans wear is reduced.

I have a parts trans from a 97 S320 ( heavy car ) that had a failed K2 bushing, worn planetary carrier, thrust washer/ bearing that fell apart causing damage to the planetary gears.If the thrust washer doesn't loose it's needles, the planetary won't be damaged. Near as I can tell this car never had a fluid change as evidenced by a filter's date code that was around / prior to the trans build date.

I suspect the post fluid change failures you are seeing are from customer feeling the trans act up then thinking that a fluid change will fix everything.


The uprated sprags are a drop in swap. One of the sprags has 3 revisions from what I recall.

The early 96 VB / TCU is different than the late 96 - 97 VB / TCU according to the ATRA manual.

Some photos in your link look like the transmission went through a war zone So no more ATF removal in my books. Message warning taken. Thanks Martin

Yes, with your '99 I think you still have the drain bollt on the torque converter, so just drain that too.

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Prost!

I would not even do the torque converter drain if it is a 90's car either...

When was the K2 bushing/bearing change? I thought it was '96, which could still include a '97 MY, but not a '99.

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Prost!

Lucky you for fixing that. 96-97 one can swap them around, but later years will not work..

Martin

After finally receiving the Sonnax kits from two separate sources, I proceeded to change the Overlap Control Valve Sleeve Kit in three different areas of the valve body. No major difficulty and after coating each valve sleeve in fresh ATF, mounting the O ring, then rolling the sleeve flat on a clean surface to ensure the O ring is sitting nice and flush, the sleeve pops in with just a bit of light pressure.

Then I proceeded to change and install the Regulating Pressure Control Valve Spring. The spring which needed to be replaced was way longer and thicker. After checking the documentation, it looks like the valve body is the later version, despite being a 99' vehicle. Looking closer on the valve body I noticed what looks like a cast date 06/02 which could indicate June 2002? Looks like the valve body has been changed since the vehicle manufacturing date. Looking on the web for part no. R1402773701, I discovered that it shares the same ID as a 2006 Dodge Van Sprinter 2500 valve body. Funnily Sonnax states in the documentation that the spring does not fit valve body R1402773801 which is not the same ID as above.

See photo of the springs. The Sonnax one is in the middle and should replace the right hand one.

So guess the spring serves no purpose now. I'll make it available to anyone who needs it. A PM and we can talk about it.

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Have a look at the numbers etched on the side of the VB, there is also a date code there.

Thanks for the tip.
I have already reinstalled the valve body in the transmission but the bolts have not yet been torqued. I could remove and check before getting everything back together and filling up with new ATF.

So I pulled out the valve body and found the etchings. One seems to be a part reference 140 06 06 and the other with a date in European format 16.03.00. So the valve body has definitely been changed during the vehicle's early life as it is a 99' MY and was first road registered in Switzerland in April 99'.

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Finished reassembly and filled with the same quantity of ATF as removed. Tomorrow will be reserved for a test drive to check everything out.

Before getting out from under the vehicle, I noted the transmission ID on the bell housing. It's R210 271 08 01. Didn't find any reference in the EPC. Any ideas?

The 210 # is the bell housing part number, not the transmission number.

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90 300TE 4-M
Turbo 103, T3/T04E 50 trim
T04B cover .60 AR
Stage 3 turbine .63 AR
A2W I/C, 40 LB/HR
MS2E, 60-2 Direct Coil Control
3" Exh, AEM W/B O2
Underdrive Alt. and P/S Pulleys,
Vented Rear Discs, .034 Booster.
3.07 diffs 1st Gear Start

90 300CE 104.980
Milled & ported head, 10.3:1 compression
197° intake cam w/20° advancer
Tuned CIS ECU
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PCS TCM2000, built 722.6
600W networked suction fan
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