atom-ant

Hi Guys,

My car developed new issue last week It is a 2008, c220 CDI auto sports.

Situation occurs when accelerating especially overtaking on motorway at around 54MPH / 88KM/h @ 1600-1700 RPM (triger point)- when I press the accelerator the car surges heavily. Ideally it should kick down to lower gear but it does not and starts surging for a bit( a second or two) till it achieves desired speed. There are no error codes on the ECU. The car does not go into any sort of limp mode.

To demonstrate this I categorically kept the car in 5th gear (manual mode) and accelerated from 54MPH upwards and it surged till it achieved the correct speed.

same happened in 4th gear. I have attached the video with reference time marker so you can observer the RPM gauge dancing under acceleration.

In general Idling is smooth, I can redline the engine, turbo hose pipes seem ok. take off from standstill is smooth with zero hesitation.

The issue is only at high speed over taking. Hopefully somebody can look into it for me please

video link https://vimeo.com/142700583 https://vimeo.com/142700583

Big Daddy

any traces of black smoke from the exhaust?

atom-ant

Thanks - didn't spot any smoke when I redline or abrupt acceleration (when the car is parked).
Observing rear view mirror as the surge is happening I was not able to spot any coloured smoke.

You asked about smoke, are you trying to rule out Trubo, EGR or delphi injectors ?

what would gearbox do; if at fault under boost/stress/accelerating. (just asking for sake of information)

atom-ant

Ok I do see some smoke after I made this video. outside temperature at cold start was 14 Degree Celsius.
Video link http://vimeo.com/142721752

NZ-Merc

Hi,
Do you think it is slippage in the gearbox/torque converter increasing the rpm momentarily or does it feel like it is engine dyeing out then accelerating.
If you suspect engine I would replace the air and fuel filters, with the fuel filter tip it upside down in a plastic bag to check for water or algae.

atom-ant

Thanks you. Had full service last week from merc. So could not be filters. The reason I mentioned gearbox is due to fact the transmission oil was replaced by my mechanic mate he is ex merc technitio (wanted to save merc labour costs) Gear oil filters etc etc were original merc. I am just conscious if oil level is low or high and causing torque converter/pressure/or lock clutch related issue.

There is no code logged else we can get a bearing for a root cause analysis.

On the other hand it could be entirely differnt issue and i am just joining two differnt pieces of strings.

atom-ant

Ok, I am pointing this to gearbox oil change. So I need advise please. I will take remedial actions ASAP.

So there is more transmission fluid than required, it is overfilled. I bought the 722.640 dipstick stick 920MM from ebay and @ 25 deg temperature (I used infra thermometer to check pan temperature) the dipstick is showing mid level instead of being in the mid 25 degree mark. Same goes for 80 degrees - the oil is well above the operating temperature threshold.

can overfill do surges. obviously i am fixing this ASAP i.e. bring the oil to right level.

sorry for typos. Mobile (fat fingers)

Carsy

You can suck it/syphon it out from the dipstick hole with a quarter inch plastic tube to arrive at the correct level rather than using the drain plug. Make sure the car is level & oil temp correct.

Interested to know whether the surging has stopped.

atom-ant

Thanks Carsy (helpful as always)

I was unable to sleep after I identified that the fluid level was higher than required. So next day; trip to my mate again (You really need to have a 'mate' to save money - especially who has a proper Xentry/Star system and you own a merc).

It was human error clearly - fluid was over by 1.6 litres. I took a photo when he was draining the fluid. In the photo the transmission temperature shown is 92 Deg C but when he calibrated the transmission level it was at 81.
So the fluid is precisely between the mid 80 mark rage on dipstick when hot and exactly mid on the 25 marker. So all good on fluid level. I did not push the new red lock pin to keep an eye for few days since I have my own dipstick and an IR thremo (£5 from ebay). I am literately paranoid. I can confidently say that transmission oil Pan temp reading from an IR thermo and on xentry/Star equipment was in near sync ( with a variation of +-2 deg c)

I have generic ELM OBD connector and torque pro app (android) and using the method below you can capture correct temperature. I did not want to write my own guide when someone has already done it So the temp from toque pro and IR thermometer match star output ( cheap solutions compared to star)

http://www.300cforums.com/forums/tec...o-android.html

So above was the fluid correction. Below is if problem is fixed or not

Like I said I did not had an issue before transmission fluid was changed so after all was in order the problem actually did not go away completely but the gear changes were accurate and very responsive. kick down just worked like I have never felt before (or I forgot how car drove before - lol) I was feeling good but when I tried to repeat the issue after I took the car from the garage to home; it juddered a little bit (less then before but it was there); the transmission would kick down to adjust speed/gear ratio.

I was a bit disappointed; rang my mate and he said could be TC is showing bye bye signs. So left the car parked and following day issue got resolved miraculously.
I have done roughly 310 miles since and was keenly looking for judder. It did not happen. ( you can imagine the 310 miles I did I was trying to get the car to show the issue ).

It is so unreal how sensitive 722.640 is towards fluid level and adjusting the level is not a difficult thing at all. In my case the oil was sucked using a vacuum tube (you hand pump it fist and oil gets sucked) - exactly how Carsy explained.

Also I had a play with Star/ Xentry - the amount of information it shows about the car is phenomenal to the level I had the phone vent mount in front of cd player a while back the cd player was not able to eject the disc due to obstruction; I forgot about this (that even was logged as fault code!!) I have the full print out of quick scan result for my car. I will scan and upload it so you can view for reference but when people say go and get star diagnostic done; it really helps towards first step to root cause analysis.

Hope this helps - fingers crossed for my transmission and long live MBworld.org

Carsy

Great news . Transmission should be good for another 50,000/60,000 km before the next oil change.

The beauty of DIY is that we are always learning