Adding M157 Turbos to S550!
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Joined: Jan 2022
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2014 E550 4Matic
Adding M157 Turbos to S550!
I’m looking for a list and P/N of the plastic lines (and whatever else needed) when changing turbos on an M278.
I have a nice set of low mileage M157 turbos to install on my 2017 S550 4Matic (which has Slav E50 tune, BlackBoost intakes and WMI already) and want to cover all the things which should be changed while it is disassembled.
Thank you everyone!
BillWoeb
I have a nice set of low mileage M157 turbos to install on my 2017 S550 4Matic (which has Slav E50 tune, BlackBoost intakes and WMI already) and want to cover all the things which should be changed while it is disassembled.
Thank you everyone!
BillWoeb
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Joined: Jun 2025
Posts: 784
Likes: 250
From: USA
Absolutely. While you're in there, you must replace all the brittle plastic coolant and oil lines. The main ones are:
* Turbocharger Coolant Lines: These are the most critical. You'll need the upper and lower plastic lines for both turbos. Common part numbers are A2785000181 (Upper) and A2785000081 (Lower). Always get new O-rings and gaskets for these.
* Turbo Oil Return Lines: The plastic housings crack. Replace both, part number is often A2780100525.
* PCV Hoses: The large turbo inlet hoses that integrate the PCV system (from valve cover to turbo inlets) get brittle. Replace both.
* Gaskets: New turbo-to-downpipe gaskets, manifold gaskets, and all associated copper crush washers for banjo bolts are mandatory.
Don't forget new turbo mounting bolts, as they are stretch bolts and must not be reused. Source these parts by your VIN in EPC to confirm exact numbers for your model year.
* Turbocharger Coolant Lines: These are the most critical. You'll need the upper and lower plastic lines for both turbos. Common part numbers are A2785000181 (Upper) and A2785000081 (Lower). Always get new O-rings and gaskets for these.
* Turbo Oil Return Lines: The plastic housings crack. Replace both, part number is often A2780100525.
* PCV Hoses: The large turbo inlet hoses that integrate the PCV system (from valve cover to turbo inlets) get brittle. Replace both.
* Gaskets: New turbo-to-downpipe gaskets, manifold gaskets, and all associated copper crush washers for banjo bolts are mandatory.
Don't forget new turbo mounting bolts, as they are stretch bolts and must not be reused. Source these parts by your VIN in EPC to confirm exact numbers for your model year.
