Just ordered a turbo and assorted hardware for my 2013 ML350. I've got north of 310,000 km - it still runs strong and gets decent mileage (7.5 to 9 l/100 km). Start and idle is clean but after a longish highway run it will put out a smokescreen that would make a freight train proud. That clears up after maybe 5 or 10 minutes. Generally just shutting the car off and restarting it will make a noticeable improvement. The car doesn't use any oil - I go 7-8,000 km between changes without adding or even noticing any movement on the dipstick. I've run a zero balance test on the injectors and they're all virtually identical and absolutely in spec. The smoke is blue/gray and might smell like oil - at first I would have said it was diesel smoke but over time I've convinced myself its oil.

I think what's happening is the turbo is pushing oil into the exhaust under boost. So not very much oil and not noticeable on the highway but enough to cause smoke at idle into a hot exhaust. There's likely some puddling that happens on the highway and needs to burn off at idle. There's "some" oil on the intake side of the turbo - no abnormal play in the turbo cartridge. I'm not inclined to tear the exhaust apart to see what the backside of the turbo looks like. If I'm going that deep its going to get a new turbo. I just ordered whatever white box version Rock Auto was selling. I choked up on the genuine MB price which was $4k (or more) in Canuckbux. I'm not sure exactly what I've ordered. The only information Rock Auto provides is that it is a GPD but I've had good luck with Rock over the years and I'm assuming if it was a piece of **** they wouldn't be selling it. I also ordered a gasket set and bolts for the exhaust flange/turbo joint. I was expecting a compression ring but it appears from EPC that it is in fact just a flat surface with a gasket.

What else does the hive mind think I should have on hand before tearing this apart?

 

Be sure to share some pics, best of luck with the project!

 

Every project should be a reason/excuse to buy tools. I've been lusting after a cordless ratchet for some time now. I've got a little 3/8 air ratchet but the air hose is a PITA so I hardly ever use it. Cordless has spoiled us all with unreasonable expectations of convenience I guess. Anyway, I used this upcoming adventure as justification to click "Buy Now" on Amazon. We've got a longish trip to BC coming up - I got the kayaks loaded this morning - we've got a condo with a dock rented in Sicamous so we'll put that behind us before I tear into the turbo replacement. By then all the various eBay, Ali, Amazon, Rock bits and pieces should have arrived. Its such a hassle making Youtube videos but there's a dearth of straight up OM642 turbo replacement vids so maybe I'll get motivated and set the camera up. I've certainly benefited over the years from others taking the time to make a video so maybe I should give a little back.

 

The cordless ratchet was useful but not as much as I thought it would be. Some (too many) places are just too inaccessible for anything except finger tips. I should have made a video because there's a dearth of useful videos about this project. But I didn't. I pulled the wipers, tray and all the trim bits by the firewall. In case someone stumbles on this thread prior to tackling a turbo swap I'll try to describe how I separated the turbo from the exhaust manifold because it wasn't dead simple or obvious. At least not to me. The turbo discharge is easy - pull three cap screws and move it out of the way. In my case there's no DPF because the car is deleted with BuzzKen hardware. With the exhaust pushed out of the way you can see the Y-pipe that connects the exhaust manifolds and then bolts to the turbo. Its pretty straightforward to get the 6 cap screws (3 each side) on the exhaust manifolds. With them loose it seemed obvious that the only thing attaching the turbo to the block was the two TTY cap screws into the pedestal. Not quite. There's also a bracket that attaches to the aforementioned Y-pipe with 2 cap screws and bolts to the block with 2 more cap screws. The problem with that bracket is that the two bolts into the y-pipe as ever so slightly angled down and I just couldn't get them loose. Reaching blind and trying to hold a socket against gravity just wasn't working. No way to get at them from under the car and they're literally at fingertip range from above. Finally I gave up on that and pulled the two cap screws that attach that bracket to the block. At that point the turbo is still attached to the y-pipe and there just isn't room to pull the entire assembly but with the turbo loose you can tip it back enough to get access to 2 of the three cap screws that attach the Y-pipe to the turbo. Those 2 cap screws go in from the forward side of the turbo through a flange and screw into the Y-pipe. The third cap screw goes in from the rear of the Y-pipe and threads into the turbo. Its easy to get at but the two on the bottom are invisible and inaccessible until you can tip the turbo up to see them. There's another short 90 degree pipe in there that's relatively easy to get out at that point.

After that its pretty simple. I just left the y-pipe loose in the car. It has to be disconnected from the manifolds so that you can tip the turbo plus y-pipe assembly to get at those hidden cap screws. Putting it all back together is just a slow mo reverse action. I goobered all the gaskets with copper never seize just because that's the way I was taught to do it. Maybe it wasn't necessary but I did it anyway. I forgot about the little 90 degree pipe until I had a lot of the reassembly finished so it was unnecessarily difficult to reinstall. If I was doing the job again WHICH I SINCERELY HOPE NOT TO DO, I would start with a clean cardboard and stick literally every fastener in the cardboard with a label. That's how I used to do Towncar dash removals and it serves two purposes. First it gets all the fasteners back into the right holes but more importantly it gives you a clear process order when it comes time to reassemble so no critical steps get missed. Whatever extra time it takes to stick screws in cardboard is more than made up in efficient reassembly.

The only torque to yield (TTY) bolts in the process are the two holding the turbo to the pedestal. They end up TIGHT. The spec I found said 20 NM followed by 90 degrees. I did the 90 degrees as 2 x 45 and it made this old guy snort using a 3/8 drive - clearly I should have used the 1/2 drive.

Its too soon to say for sure whether I fixed my smoke show but I'm optimistic. I took the car for an hour drive this morning with a stop halfway and didn't see any smoke then or when I got home. Didn't have any codes when I got home so gotta love that. I was worried because I couldn't find a procedure in Xentry to learn in the turbo variable controller. I asked Peter (BenzNinja) and he said it wasn't always necessary. Both ChatGPT and Grok concurred that it wasn't always necessary. One of the AI agents - can't remember which, but completely unprompted - specifically called out my GPD turbo as an example of a brand that often comes pre-calibrated. I thought for sure there should be an option in Xentry to do the learn in but there was nothing visible so I have to assume that option must only appear when it is in fact possible. I got on the throttle enough this morning that I should have seen some under or over boost codes if there was going to be a problem. Those of you who have read this far will have noted that I glossed over the fact that I cheaped out on the turbo purchase. I just couldn't stomach well north of $3500 Canuck bux for a genuine MB. The GPD variant was about $700 delivered from Rock Auto. I told myself if Rock was selling then it couldn't be absolute crap. I'm still not 100% in love with this car. I absolutely love driving it - we just got home from a 2,500 km trip carrying 2 kayaks on the roof, running with the big dogs on the Transcanada Highway, climbing mountains with ease and returning fuel economy into the high 8 litres per 100 km. When its on the road its a dream to drive but its spent all too much time being a shop nightmare for me to completely love it.