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Went into the dealership for B service today at about 77,800 miles. They said the turbos have supply and return oil lines, and the driver's side return line is weeping/leaking at the connection to the engine. Repair was quoted at $1,900 and at that price, I imagine it's 95% labor and 5% parts. Before I bite the bullet, maybe someone here has done that repair and can generally describe all the things that need to come out to access that, and if any special tools are needed. I imagine it's probably a 4 or 6 hour job on the book, I would hope I could get it done in a weekend??
Mind you the above is for a 2020 c43... but FCPEuro shows fitment for 2017 as well.
These lines have o-rings which might be all you need? If it was me, id just get a new part.
Seems straight forward. I'd take on the challenge if it was me.
Thanks for the info an link! FCP Euro is great. Any idea what all has to come out of the engine bay to access this? For a $1900 dealership quote, I'm sure a few items need removed for access. Also, that document you shared shows a tool I've never seen - Hose Clamp Pliers. I'll have to look into that!
2023 E 450 Sedan. 2018 GLC 300. 2013 E 350 Coupe (retired)
AI says:
Replacing the turbo oil feed line on a Mercedes C450 (typically equipped with a 3.0L twin-turbo M276 engine) involves removing the heat shields and accessing the oil line, which is often done from the top or underneath to replace the line,, and its O-rings, which frequently leak due to heat hardening. The process requires removing the engine cover, heat shields (often using E10/E12 bolts), and using specialized tools for tight spaces.
This video shows the process of replacing the turbo oil line, which involves removing the heat shields and the oil line itself:
Replacing the turbo oil feed line on a Mercedes C450 (typically equipped with a 3.0L twin-turbo M276 engine) involves removing the heat shields and accessing the oil line, which is often done from the top or underneath to replace the line,, and its O-rings, which frequently leak due to heat hardening. The process requires removing the engine cover, heat shields (often using E10/E12 bolts), and using specialized tools for tight spaces. This video shows the process of replacing the turbo oil line, which involves removing the heat shields and the oil line itself: Key Steps for Replacement:
Preparation: Allow the engine to cool completely and place a drain pan underneath to catch oil.
Accessing the Line: Remove the plastic engine covers and the heat shielding surrounding the turbo to expose the oil supply line.
Removing the Line: Locate the bolts securing the line to the engine block/head (often 8mm or E10 bolts). Using a long extension with a swivel/wobble socket is necessary for accessing the lower, tight-fitting bolt.
Replacing Seals: The leak is often caused by hardened rubber O-rings. Remove the old line and install the new line with new seals. Using a lubricant (like plumber's grease) on new O-rings is recommended to prevent them from snagging upon installation.
Reinstallation: Reconnect the new line, ensuring it clicks into place on the lower connection, and torque bolts properly.
Priming: Lubricate the turbo bearings by pouring new motor oil into the oil feed hole at the top of the bearing housing while rotating the compressor wheel to prevent dry start.
Required Tools:
E10/E12 Torx socket
8mm socket
Long 3/8-inch extension with a swivel/flex head
Long pick or flathead screwdriver
Torque wrench
If the leak persists, it may be necessary to check the oil cooler seals or other gaskets.
Looks like there are many YouTube videos
Mercedes turbo oil line replacement cost varies widely, from a few hundred dollars for just lines on simpler models (like $200-$300 for a CLA250) to over $1,000 for complex jobs or full turbo/line kits, with labor (often 4+ hours) being a big factor, potentially adding $700-$1000+ for labor alone on top of $100-$500+ for parts, so expect a range from $300 to over $1,500+ depending on the model, parts quality, and shop rates.
Last edited by smiles201; Jan 25, 2026 at 06:52 AM.
Replacing Seals: The leak is often caused by hardened rubber O-rings. Remove the old line and install the new line with new seals. Using a lubricant (like plumber's grease) on new O-rings is recommended to prevent them from snagging upon installation.
@smiles201 Thanks for the AI details. Wouldn't engine oil be a good lubricant? That's what I use on new seals on engine oil filters, cannisters. I'll be looking for and studying videos. I have all the tools mentioned on your list. I wonder why the document shared by @atomek shows the special clamp pliers? I guess watching videos will explain if that is a necessary tool or not. I'm looking forward to doing this repair, getting to know my car better, and saving some cash! Love mbworld.org!
I wouldn't be to hung up on the specialty tools. I think its a tool designed to unclip things in hard to reach areas. These things are designed for mechanics get things done quick.
I'm sure you'll be able to reach whatever needs unclipping with some pliers. If it becomes hard to reach, then you might need to make a trip to a hardware store and pickup some long reach pliers.
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