Hi all,
My 2005 CLS 320 CDI 7G Auto on 100k has a fault when accelerating. It seems to happen when the car is warm between 40-60mph in 3rd and 4th gear at about 2500rpm-3000rpm.

When at about 40mph in 3rd gear and you put your foot down, the revs go to 3000 and the car begins to judder and shake. After juddering for a few seconds and not really increasing speed it switches to 4th gear in which it accelerates without any juddering until at about 2500rpm. When it gets to 2500rpm it starts to judder and vibrate again up to 3000rpm. It then stops when it goes into 5th gear and accelerates smoothly as it should upwards without any vibration.

It doesn’t always do this and it happens about 50% of the time when at 40 and you put your foot down. When the car is juddering, if you immediately let go of the accelerator pedal and then put your foot flat again, sometimes it accelerators all the way through without any juddering and other times it starts to judder again.

Initially from reading online and calling Mercedes Specialists they advised it may be the transmission. A Mercedes independent specialist changed all the ATF fluid and filter last week but it doesn’t seem to have fixed the fault. (It appears this was the first time the fluid had been changed because it was filthy and had not been changed according to the service history.)

Normally it never goes into limp mode and there are no warning lights displayed when it judders. But the last time it happened the car went into limp mode. I’ve ordered a fault code reader so hopefully there will be a fault code registered from the car going into limp mode. The car had its filters changed at about 87k but I have ordered another fuel filter just in-case.

I’m probably going to have to go to another specialist to get it looked at but would appreciate some advice as to what it could possibly be from this forum beforehand.

Any theories anyone?

 

This video is what happens when I try to accelerate.

http://www.youtube.com/watch?v=WMN_y...ature=youtu.be

· 10 seconds - At 40mph I put my foot down and start to accelerate

· 11-13 seconds – you can see the car shaking and although the revs are high the car is not really accelerating in speed

· 14 seconds- you see the revs dip down and the car shifts to the next gear

· 15-17 seconds – the car increases speed from 45-55mph smoothly without any vibrating

· 17-19 seconds – the car starts frantically vibrating again

· 19-21 seconds – although I still have my foot steady on the accelerator the whole time the revs dip down and the car now goes into limp mode not letting me increase speed.

 

It's either the torque converter shuddering or the gearbox is slipping. If it's logging a fault code and going into limp then it's more likely the gearbox is slipping.

Using the factory scan tool (DAS) you can turn off the torque converter lockup clutch and test drive it to see if the shuddering stops. If is still shudders then the gearbox is slipping.

Try a similar load in other gears as well. If it's mainly in 3rd and 4th gear, a little in 5th but no other gear then it's most likely the gearbox slipping (K1 Clutch).

Considering the mileage, no service history and the high torque of the diesel engine you might be looking at a rebuilding the gearbox unfortunately.

 

http://www.pistonheads.com/gassing/topic.asp?t=1207827

From reading online on other forums if it was the gearbox slipping, would I not experience transmission slipping when changing gear rather than a vibration/judder as accelerating through in a certain gear?

If it was coolant leaking into the transmission fluid or the gearbox dieing on me would the car not have difficulty selecting a gear or it slipping out of gear?

 

well my friend , i would recommend :
1- check you oil ( level , smell , color )
2- change oil and filter
3- test drive it , hopefully it will be ok

if not then you should first check for fault codes by using diagnosis tools and after that you dive further in repairing that transmission ...
usually slipping and juddering hapens when oil pressure is low , that is caused by many things , not enough oil , clogged oil filter , busty oil pump , and burnt clutches inside the tranny ... hopefully in ur case its only a matter of a filter and oil change and that no further damage happened ...

keep us posted on what happens with you ...

 

Coolant leaking into the gearbox would make it shudder in all gears, but usually light loads only. Coolant only causes shift problems when there is heaps in the gearbox and it's been there for ages (causes rust and sticking valves in valvebody). In other words, you'd know about it well before it got to this stage.

The transmission ECU can see slip in the torque converter and also the gearbox as a whole (wont narrow it down to a individual clutch, just that the input vs output speed don't match it's expected gear ratio). If there is excessive slip in the TC it logs a code, but that's about it. If it slips in the gearbox it will log a code and put gearbox in limp mode (holds whatever gear it is in, no upshift or downshift) until restart.

Without driving it or looking at transmission adaptation data and fault codes, my best guess is that there is a damaged piston seal and it cant maintain full pressure to the K1 clutch (engaged for 3rd, 4th and 5th gear). This explains why it's ok to apply the clutch and gentle driving but slips at higher engine torque levels.

 

Considering I have had all the ATF changed 2 weeks ago by a specialist do you think that it could be be the fluid?

Ive had the car scanned with a OBD code reader and it didn't bring up any fault codes apart from a oxygen sensor (P0132) and glow plug control (P0670)? Very strange considering it goes into some sort of limp mode if I hold down the accelerator all the way through the juddering.

I also wanted to test if the car does this when its cold; so it was at about 45 degrees and in 2nd gear at about 30mph when I put my foot down and car juddered so the problem now seems to be occurring in other gears too.

Going to get it connected upto STAR tomorrow for a proper diagnostics

 

An obd2 code reader can access only fault codes in engine control module . It cannot read codes in transmission ...

 

I am almost sure its not transmission.
Turbocharger or EGR

 

I had previously got the AFT fluid changed so Wayne Gates Mercedes said they would take the car in for a week to try and diagnose it. We initially thought it was the gearbox or torque convertor but 3 days after I received a call from the garage explaining it was probably about the worst juddering fault they had ever felt and had found iron fillings coming out the turbo. They knew it wasn't the torque convertor because if it was faulty the car would vibrate moderately. If it was the gearbox it's likely to vibrate when actually changing gear rather than in the gear. They tested this by keeping the car in manual mode and the juddering still took place at about 2500revs- 3000revs. They explained the juddering is being caused by the exhaust manifold which is double skinned breaking down and being sucked into the turbo. So I ordered a recon turbo, manifolds and gaskets.

I'm happy to say the problem has finally been fixed. It was a very expensive fix but it is common for the exhaust manifold to fail on these engines at about 100k. Wayne Gates were absolutely excellent. It certainly pays off to take the car to a specialist otherwise you will just end up getting messed around and replacing lots of parts unnecessarily.

 

Great info !!! Thnks for sharing

 

Thanks for the info punz. What is the double skinned manifold made from ?

 

Hey... i have 2008 320cdi..... it was going in limp mode when i bought it which was resolved by fixing the turbo regulator.... but then the juddering has continued but only when its cold....once the engine and gearbox warms up shes a beauty...... the local specialists....dronfields..... said its a sensor on the exhaust system...i think thats what they said.... about 86 quid for the part.......