Hi folks.

Car in question is my wife's 2012 ML350, so I will also post in the ML350 section. Yesterday I changed the oil, air filters, fuel filter, and transmission filter and fluid. Today she drove it about 15 miles and it started shaking and losing power. We had it towed home and I had a little time to mess with it before dark.

No obvious leaks anywhere, so I took it for a drive. I got about a block and it did what she said it did. I stomped on it and it picked up very slowly and would not shift until I lifted up on the pedal. The engine is not revving like the trans is slipping, there is just no power, but it idles smooth and starts up normally.

The only anomally I had was yesterday when I drained the trans fluid out of it I got about 4.5 quarts out of it as measured by a measuring cup. So I refilled it with 5 liters of the proper blue transmission fluid. Now the transmission kit I got from ID parts came with two 5 liter jugs of fluid, but I only used one. 4.5 quarts = 4.25 liters

My questions....

First off, do you think I have a fuel problem or a transmission issue? Second what is the approximate amount of fluid needed for a drain and fill on a 722.9 transmission? Third, I drained 4.25 liters out and refilled with 5 liters. Is it possible the transmission still under filled, or overfilled (I don't see how .75 liters would cause this issue). Lastly, it first started after 15 miles of highway driving so the trans fluid was hot. Now it will do it after sitting for 6 hours and the fluid is cold.

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2012 Mercedes ML350 Bluetec 91K (hers)
2005 Corvette 55K (fun car)
2002 VW Jetta TDI 231K (mine)
1998 Volvo S70 T5 Turbo 196K (kids)
1994 Ford F150 4WD 249K (firewood hauler)
1983 Mercedes 300D 376K (diesel commuter)

I also have a 2012 ML350. I was thinking about servicing the transmission myself but after reviewing some U tube videos on the procedure decided to have it done professionally. As you know there is no transmission dipstick tube. The refill procedure uses a special fitting to refill the trans with the blue fluid. If I remember correctly it took almost 9 liters to properly do the job.

All,

Many thanks for the help and all the suggestions, I'm pretty sure I have a fuel leak/issue. Tonight after work I had about an hour of daylight to mess with it, and long story short, the the engine plastic skid plate and the transmission skid plate as well as the cross member behind the engine are damp with diesel fuel. I noticed both were damp/stained and when I wiped the residual off it smelled strongly of raw diesel fuel. Sooo, I have a nice little fuel leak somewhere.

I'm hoping it is the fuel filter or one of the rubber lines, as that is the only part of the fuel system I messed with (fuel filter change). I guess the best course of action is either pull the skid plates and see if I can trace the leak that way, or pull the fuel filter and check the rubber line.

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2012 Mercedes ML350 Bluetec 91K (hers)
2005 Corvette 55K (fun car)
2002 VW Jetta TDI 231K (mine)
1998 Volvo S70 T5 Turbo 196K (kids)
1994 Ford F150 4WD 249K (firewood hauler)
1983 Mercedes 300D 376K (diesel commuter)

Just an update. Ended up having to take the car to a shop as I could not find the leak. I was paranoid the high pressure fuel pump let go......turns out one of the fuel return lines buried under all the other stuff behind the engine had let go. $7 part, $135 in labor to get to it!

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2012 Mercedes ML350 Bluetec 91K (hers)
2005 Corvette 55K (fun car)
2002 VW Jetta TDI 231K (mine)
1998 Volvo S70 T5 Turbo 196K (kids)
1994 Ford F150 4WD 249K (firewood hauler)
1983 Mercedes 300D 376K (diesel commuter)