A bought a new 2008 S600 6 years ago and have to date been very happy with it. Over the past year however, a recurring transmission issue has been really irritating me and my Service Advisor is not having any success in addressing it. I wondered if anyone recognizes the problem? It is pretty simple.

Whenever (especially from cold) the 5-Speed changes from first to second gear, a pronounced "shudder" runs through the entire car lasting about 1-2 seconds, resulting in a pronounced jerk or "snatching" motion that is also audible and pretty obvious to passengers. It does not feel right at all for an S-Class. It is now at the point where I can't put my foot hard on the gas from rest without this audible shudder/jerking motion at the first/second change point. Once I am over the first/second gear change all other transitions up to fifth and down again, are fine.

Reviewing the history of the problem, everything was fine for my first 5-years until the transmission fluid was changed during a scheduled service just over a year ago. Apparently there was a faulty seal/part and the transmission fluid leaked out after a few days later, and I had to limp back to the dealer to have the problem fixed. It was after this that the shudder/jerk started appearing. When I took it to the dealer they could not at first reproduce the problem and suggested it might be because the gearbox had warmed up, but it slowly became more pronounced over the following months, though the car was quite driveable otherwise.

At my last service the SA reported that the shudder/jerk had been identified as the torque converter locking up. They removed it and replaced it with a completely new torque converter under my extended warranty. When I first drove off a couple of months ago, the problem seemed to have gone away but now it is back again! I called my SA and he suggested I give it a few more miles for the updates to settle in and for the transmission to reprogram but the shuder/jerk at first/second gear change has not gone away. In fact the transmission has never been the same since that fluid change over a year ago.

I have been wondering whether this is a software issue in the transmission, or whether there is still a torque converter problem. It is more pronounced when the car is cold but it happens when the car is warm also. It is beginning to really get on my nerves. This car should be smooth when driving off from rest right? I should not be having this jerk vibrating through the car whenever I transition from first to second gear.

I vaguely recall a mention on this forum of an issue in the 5-speed similar to mine, but I can't find a reference. Does this problem appear familiar to anyone? I am currently at 55,000 miles and am still covered under my 7-year extended warranty until it expires next September. I really want to get it properly sorted before then.

Chris

 

I had a very similar shudder on our SL600TT in very similar situation. Turned out be completely unrelated to the transmission. This typically was recognizable in low speed/rpm and especially when cold. This was felt mostly in the midsection of the car...

The culprit were the motor mounts which had collapsed (quiet normal at your mileage with a heavy, high-torque engine).

It cost close to $3k if I recall as they engine had to be completely removed from the SL to replace the cheap motor and transmission mounts.

Have MB check the mounts; wouldn't surprise me if that's the issue...

 

I greatly appreciate the suggestion about the motor mounts. The dealer inspected them and found them OK. However in test driving the car from cold the following morning, the jerk/shudder was apparent again. After further investigation, they told me a valve and an electronic circuit board in the transmission needed replacing, but on closer inspection of the transmission interior I was subsequently told they spotted other things they don't like, metal debris/shavings in the transmission fluid apparently. I will get a full report soon.

I thought the 5-speed was pretty bullet proof and I am an undemanding driver.

The result is that they are replacing the entire transmission of my car with a new one. Just waiting for it to arrive.

THANK YOU Extended warranty! (6-years in)

Chris

 

Cj Hopefully the new tranny restores your 600 to the smoothness you have come to expect. Keep us advised. Good thing you opted for the extended warranty!!!

 

If dealer replaced pilot bushing (part # 2035400253) for initial leak ATF can wick up through electrical harness into TCU (part 0034464110) if so, TCU should have been replaced at this time. Additional possibilities: torque converter (TC) clutch sometimes resolved by software update (but this should have been checked with TC replacement) and/or faulty solenoid/valve in electronic-hydraulic control unit (valve body) within transmission requiring replacement. Now metal shavings, definitely push for complete transmission replacement under warranty.

 

OK I have my S600 back with a brand new transmission, it drives perfectly, and is back to how it used to be. Here is the report from the service documentation, if it is of future use to anyone who encounters a similar problem:

"Client states that when the engine is cold, there is a transmission jerk from 1st to 2nd gear shift - report CPO Warranty. Test drove the vehicle. Able to duplicate customer concern and determined it is the torque converter locking up at the wrong time. Quick test. DTC 0743 The internal electrical check of torque converter lock up solenoid valve has failed. Drained fluid from transmission. Fluid dark and dirty. R&R valve body to replace solenoid valve and found lots of debris from clutch packs and some metal. Recommend replacing transmission due to debris.

R&R transmission. Flushed torque cooler line and transmission cooler. Flushed torque converter. Replace transmission.Programmed intelligent servo module on side of new transmission. Set fluid level. test drove the vehicle to verify repair. Transmission shifts normally. Cleared DTS. Done."

Thanks all!

Chris

 

any ideas on what the cost would have been?

 

Quad, Im not sure i want to even see that figure!!!

 

I asked of course! I believe it was around $8,500. The SA (At MB of Oakland here in CA) said that they discount much of (or all of) the labor on warranty work, so I am not sure how much of that is parts and how much labor if any. (I am fairly sure it would have been more out of warranty at commercial pricing)

BTW: I was treated very well, and given a fully loaded C250 as a loaner while all this work was being done. (It was not your average base model and even had all the Sirius radio stations active)

Chris