W203 C220 Auto Box issue, easy change

[ThPadd]

Okay guys I have been hunting online for the answer to this, but not found the answers, so any relevant experience appreciated.

I have had my 06 C220 for a couple of years now and after sorting out various issues (track rod arm, front discs, tyres, unlocking), I now have just 2 niggles that stop me loving this car to bits (its the Avantgarde, black on black, 5 spoke alloys).

Firstly when cold, and po0tling down to the end of our road at 30mph (usually on cruise as it gives me time to find the right radio station, get my satnav set etc), the revs rise and fall slightly. Car checks out fine at my local indie (Prospect Solihull), but by the time I get it to them its always warmed up. Not the end of the world but just a bit annoying.

However the gearbox is a right pain in the bum. When its cold, you pull off gently, get to the end of the road and then have to pull out into traffic. You pull off and its like nothing is happening then all of a sudden it either engages gear with a jolt or kicks down, I'm not sure. Its a bit scary waiting for it to happen with traffic bearing down on you and probably not doing the gearbox much good! This is in C mode (Comfort?) which I prefer as I'm not a fan of S (Sport?) mode, its a bit boy racer for me. Once warm its fine.

I took it to Driver Transmissions in Birmingham (recommended by Prospect) and of course by the time I got there the gearbox was warm and it drove perfectly!!

I have had the gearbox oil changed and have bought a dipstick so I know the level is fine, So I was wondering how hard a swap out would be. I may even get one and get Prospect to do the work as they have the lift etc. to make this easier. I can get a gearbox from a breaker for £2-300.

Any thoughts or advice??

Padd

 

[LostKiwi]

Andy Rudge is your man for this.... he did his CLK box twice!
I helped last time and it wasn't too difficult (but we had the benefit of a hoist).
Most of the work is under the car.
Essentially the process is:
1. Disconnect battery and drain oil from transmission
2. Remove starter motor.
3. Undo torque convertor from flywheel.
4. Undo propshaft couplings (You'll need to remove rear gearbox mount but refit loosely when done)
5. Undo selector lever clip.
6. Remove wiring harness connector
7. Remove dipstick tube.
8. Undo bell housing bolts (leave one in place underneath to support box till ready to remove).
9. Support back of engine (block of wood across the back of engine and sitting on front arms works well).
10. Undo rear gearbox mount and remaining bel housing bolt and lower gearbox and TC as a unit.

The gearbox is HEAVY. You will almost certainly require assistance to control it coming out

Reassembly is the reverse of assembly with the following caveat:
The TC MUST be fully engaged on the oil pump on the gearbox BEFORE assembling gearbox into car. Measure the distance from TC face to a straight edge across the bell housing. It should be at least 6mm. Failure to do this will destroy your oil pump in the gearbox and make for a LOT more work.

Also.... make sure the gearbox is exactly the same. Get the numbers off the side (it will be something like 722.616). These number MUST be the same .
There are various different versions of the 722 gearbox and these have different characteristics and torque handling capabilities.

 

[Arzaam]

to be honest if it only does it when cold its considered normal, I have seen a couple cars do it its to help the engine warm up faster but if you just started it and get going and try to go uphill or merge than the shift is harsh but still I wouldn't consider it a fault if it doesn't do it when warm or go into limp mode requiring a restart of the engine. Mine also does this since years and dealership also checked it and considered it normal and I drove two other cars which would do the same all 722.6 boxes.

 

[LostKiwi]

What i happening is that 'C' mode will by default try to start in second gear. If you put your foot down hard it will start trying to move off in second and then downshift to first hence the delay and sudden clunk as it kicks down. Kickdown when cold is always a bit jerky as the internal oil pressures are all over the place.
Try it in 'S' mode next time. It should pick up more smoothly and rapidly. If so then there is nothing wrong with your gearbox.

 

[ThPadd]

I tried Street mode at lunah. Still seems to jolt I think from 1 to 2. A recon box is a lot of money so I may risk a box from a breaker It is annoying.

 

[LostKiwi]

These boxes can be a little jerky when cold. It's just a matter of degree.

 

[ThPadd]

Okay, bit more info. It does it on cold, and is okay when warm. Only trouble it is now heading to winter so that will be nearly all the time for the short trips I do mostly. It does it on C and S, so I cant work round it. It seems to be from first to second, but cannot confirm that (need a long road so I can get it to jerk, then count up to 5 on the gears and use the tiptronic to check that it is 5). So I'm looking at a recon gearbox plus fitting as I don't have the drive/garage to do this myself.

 

[ThPadd]

Okay guys, I have pushed this issue a bit further. I did a short run, then coming home had the road to myself so played with the tiptronic. Its definitely the change down from 2nd to 1st. I looked into a recon gearbox.......£1800 fitted, ouch! I could get another unit, its a 722699 but that may also be U/S, and fitting would be £750.
Had it on a diagnostic check at my local indie today and there's no fault codes at all, on the gearbox anyway.
I'm going to check oil levels tomorrow, cold engine not running, cold engine running, warm engine stopped and warm engine running. I'm wondering whether, when cold, the level is low, running makes it lower (as it sloshes up the walls and sticks) and warm, the oil is stabilised and okay. Maybe a slight overfill will help?
I only say this as I own a 1983 Kawasaki 750 Turbo and if you fill it normally (middle of sight window), when parked the oil sneaks past the turbo bearings and into the exhaust..... smoky smoky, But at the bottom of the sight window, no smoky smoky.
Maybe its one of those little tricks we haven't discovered/shared yet???

 

[Steve@Avantgarde]

Why are we talking about replacing this gearbox, clearly there is nothing wrong with it? Apart from a snatchy cold shift when being driven in C mode. If there was something mechanical you would have seen bits of debris in the sump when you did the oil and filter change.

Question is, does it do this in S mode? Not think, specifically. If its yes then we need to look at the adaption data of the shifts and the fill times of the packs, that will be in actual values on STAR. There will be a clue in the fill times as to whether you have a mechanical issue inside the gearbox for sure.

If the fill times are ok, I would perform an adaption reset, then an adaption set up with the STAR machine with the vehicle being driven.

Then drive the car to adapt to your style for 1000 miles.

 

[ThPadd]

Hi Steve, please can you be careful about what you say. I am actually excited that you may be able to solve my problem without it costing me an arm and a leg. In fact, I'm going to pop out to the shop and test what's happening in S mode then will probably call you, if you don't mind. The thought of my baby getting fixed is like having a real child that's reached the top of the list for a life saving operation!

Just spoken with Steve, car booked in with him next Wednesday. Watch this space.

 

[ThPadd]

Okay, I went down to see Steve yesterday, they put the diagnostics on the car and it showed no issues. This combined with the fact that the issue only appeared when the engine temp was below 60C and was accompanied by the engine hunting if you tried to use cruise control when it was cold, indicated a torque converter lock-up clutch valve. So he put one of the guys on it and a couple of hours later I was good to go. They looked after me really well with a warm reception, coffee, magazines to read, and lots of chat about Mercedes cars. I kinda knew I was in the right place by the McLaren SLRs being worked on and the Maybach outside.
Anyway I couldn't really test the car till it was cold, so have just taken it for a test drive. Of course, it now behaves perfectly, and the problem was just what Steve says it was. Steve has worked for Mercedes, McLaren and Ferrari and is like a walking encyclopaedia. Just a flipping shame he's 100 miles away!
So if you do have a problem with your Mercedes, do what Steve says, and get it diagnostically checked. If your local Merc Indie cant find the problem, then call Avantgarde (Clevedon, Bristol) and talk to Steve on 01275 217270. In fact, if you are close enough, arrange to take it in, then they can tell you what's what. These guys deserve your business.
Thanks Steve, you just saved me a huge amount of money on a recon gearbox. I'll put it towards that CLK I was babbling on about!

 

[e55amggary]

Interesting

I only live up the road in Bristol. If i have any issues , nice to know Steve is close. Sounds like he knows his stuff.

 

[Steve@Avantgarde]

Thanks for the feedback! Glad we managed to get it sorted for you. Surprised the other Indie couldn't sort it for you, but there we are!