Hello Forum:

I have a 2009 GL320 with the BlueTec OM642. Yes, I have read many posts on this motor. I believe that I have a turbo leak, but before digging into the motor, I was hoping that someone with a similar experience could provide some guidance.

The motor starts instantly and idles smoothly without any vibration or unusual noises. There is no significant oil consumption. The motor has rebuilt fuel injectors (including new coding) and both the PCV valve (back of engine), and batwing (cracked at turbo entry) were replaced. When the motor starts, there is blue smoke in the engine compartment. There are wisps of blue smoke in the rear of the motor, but stronger plumes in the front of the motor ... from the valley area. The seals on the turbo pipe and resonator were replaced and a borescope used to ensure that the turbo pipe seal at the turbo outlet was correctly placed. The seals were also replaced at the EGR cooler exit.

I believe that the turbo is the source of the leak because there is a hissing sound when I accelerate. Since it is blue smoke in the engine compartment, I am assuming that the turbo leak is on the exhaust side. I am not familiar enough with turbos to know where exhaust leaks may exist. Well, I suppose it could be at the up-pipe connection, but would that send most of the blue smoke to the front of the motor? There is also the diesel smell.

I tried to use the borescope around the turbo, but it is too tight in that area for a thorough inspection.

My question to the forum is where do you believe that the leak may be based on your experiences? Would a cracked or damaged EGR cooler also cause a hissing sound and blue smoke?

Thanks!

 

So the blue smoke is burning oil and what it seems is you have a leak in your exhaust. Two lovely issues.
I’ve torn down my om642 intake and exhaust apart a few times and you will have to buy some new parts when inspecting your system. Exhaust bolts, gaskets but on the intake charge side you can reuse it all unless worn or damaged.
To find your first issue the oil being burned.
- Oil before turbo would be your pcv valve - I put a new one in and an oil catch can in-line to stop that issue.
- Oil after turbo on the charged side would be failed seals in turbo.
- Exhaust side have fun taking the back three bolts off the turbo and the clamp a little lower down to see if there’s oil at the back of the turbo so see if the seal on that side of the turbo is leaking.
- If all that is clean you have either bad stem seals or bad oil rings on the pistons.

Find out why you’re burning oil because you might have to change the turbo and a bunch of other gaskets that might fix what sounds like an exhaust leak. If you can jack up the vehicle and look underneath near your headers you might have a leak around there but it would sound like a tick not a hiss and while your under there look around the egr system for exhaust leaks to.

I personally been chasing white smoke which turned out to be two bad injectors the dealer couldn’t find and now I’m chasing the blue smoke which made me replace my turbo and add the oil catch in-line to the pcv. I’ve come to a conclusion that it either my stem seals or oil rings are gone (washed out by bad injectors) or carboned up. Best of luck

 

Were you able to chase down the problem? I'm thinking my problem is an oil leak in the turbo. I have a white-bluish colored smoke that comes out the exhaust. Also intermittent misfire on cylinder 6. A bit of smoke does come from what appears to be the middle of the turbo. I was reading that you might be able to get the repair covered under the Mercedes emissions warranty, but not sure I want to give the dealership my trust.

 

I have the same issue, and I am really interested in seeing how you resolve this. The only difference I have is that my sound on acceleration is more of a whine/whistle on acceleration and deceleration. Also, my smoke only appears visible soon after a start, but I can smell it all
the time.

 

@pjhiggins I think a little amount of oil is collecting somewhere in your intake. When you start the vehicle, it's burning it off.

I decided to take off the intercooler and found about a quart of oil. Does that sound normal? I'm thinking this may be causing the smoke problem once the vehicle gets warm. Probably oil from the PCV valve or possibly the turbo seal. Guess I'll need to put it all back together and test to see if the smoke has gone away.