This is the 3-liter V6 OM642 diesel engine from Mercedes. Today, we’ll examine the motor’s number one problem. If you fix this, you’ll avoid the frustration of a failed turbocharger.

The issue with this engine’s design is where the turbo meets the air intake pipe. The intake pipe connects the air filters to the turbo, and the turbocharger inlet gasket with a clamp connects the intake to the turbo.

Every time this pipe is removed, the turbocharger inlet gasket needs to be replaced. Once the gasket comes off, it will not reseal correctly, and you will develop air intake leaks all around the turbo. This will result in the mass airflow sensors not having the proper amount of air and this will cause reduced fuel efficiency, lower power, and maybe even limp mode or a check engine light.

The second thing to worry about is where the CCV connects. The problem with this location is that the CCV tube isn’t held in place very well, and if the gasket isn’t sealed properly, the CCV tube can start to shift out of place. That gasket can wear down and eventually need to be replaced. A failing gasket will let more outside air directly into the turbocharger and cause the MAF sensors to read improperly. If the plastic is broken, it’s likely because the pipe was removed or installed sloppily and the pipe can not seal if it’s broken.

This is where you can replace the gasket connecting to the turbo. IDParts sells a repair kit complete with all of the gaskets for this job and is available now.

You’ll have to disconnect the MAF sensors and then remove the Y-pipe. Inspect the area where the gasket connects the intake to the turbo for any damage. The plastic pipe right by the gasket is known to snap if installed incorrectly.

Another indicator that the turbo inlet gasket is failing is oil collecting on the harness right below the turbo and intake. A failing gasket will allow oil to escape the intake and drip down on the servo motor. This could cause that motor to fail.

Next, take a look at the CCV gasket and if you notice the ridges on the gasket are worn down, you should replace the gasket.

Another major source of leaks is the turbocharger outlet pipe. This metal pipe has an O-ring where it connects to the turbo outlet.

It is very common that this O-ring is sliced in half, allowing oil to spray out when compressed air moves through the pipe. This happens because if the O-ring isn’t flush or moves a little bit out of place when the pipe is installed to the turbo outlet, the O-ring is in the way of the pipe and it gets cut. Another potential symptom of this is noticing an oil smell in the cabin because the leak allows compressed air to force oil out of the pipe.

You’ll have to disconnect the turbo outlet pipe from the black plastic intake silencer before removing the pipe (you shouldn’t have to take the serpentine belt off for this). There is another O-ring between the turbo outlet pipe and the silencer that you can replace while you’re doing this (pictured below). It’s a black O-ring that may lose elasticity over time so it should be replaced.

Back to the turbo outlet pipe O-ring, we suggest that you put the O-ring on the turbo when you are putting the outlet pipe back on rather than the other way around. When you push the pipe on, it will pop and you should feel the O-ring slide into place. Then you should start to put the bolts back on for the turbo outlet pipe before re-installing the silencer.

After the silencer and outlet pipe have been installed, you can replace the turbocharger inlet gasket that started this whole project. Remove the old gasket and clean the inside of the intake pipe to remove any oil from where the gasket will go. Then, take the new gasket and install it into the pipe inlet. Be sure you push the gasket all the way in and that the round and square pegs are in the correct positions.

And finally, the new CCV gasket that we determined should be replaced should be installed. One side of the CCV gasket has a little slot that you should make sure is lined up.

Now you’ll re-install the Y-pipe by reconnecting it to the air filters and the turbo. We recommend you do this by installing the CCV connection first with the new gasket, slotting the left side of the Y-pipe into the left air filter, and then focusing on lining up the turbo inlet seal with the turbo. This allows you to properly slot the turbo inlet without the air filters getting in the way. Make sure the turbo inlet on the intake pipe is completely flush with the turbo so it doesn’t have room to leak. Once the pipe is in place on the turbo inlet, you can tighten the clamp and then re-attach the air filters.

This is the #1 cause of performance issues on the OM642 motor. So if you were thinking about spending money on new turbos, or new actuators, or new anything, give this a try first. You’ll be surprised how replacing these 4 seals will help your engine perform better.

Included in this job:

Turbocharger & Intake Seal Kit (OM642 Mercedes)

In stock now and ready to ship, this is the only set of components needed for this repair.

To view this repair as a video tutorial, check out our YouTube page below!