Mercedes-Benz Turbo Intake Pipe Replacement

Need to replace your Mercedes-Benz turbo intake pipe? By following the procedures below, learn how to remove and install your turbo intake pipe. This guide provides instructions on how to replace turbo intake pipes on a Mercedes-Benz M278 engine.

How to Replace Mercedes-Benz Turbo Intake Pipe

Symptoms

• Poor acceleration.
• Whistling or hissing from the engine bay under acceleration.
• Check engine light, often with lean codes P0171 and P0174.

Confirm the Leak First

The plastic intake pipes between the air filter and the turbochargers on the M278 can crack with age and heat. Unmetered air gets in after the MAF sensors, which can cause lean codes and poor acceleration. Inspect the pipes and their rubber ends with a flashlight, flexing them gently to reveal cracks. A smoke test confirms a leak quickly. A scan tool such as the YOUCANIC UCAN-II Pro can read engine codes and show fuel trims for each bank on supported models, so you can see whether one side is running lean.

What you will need

Parts

• Mercedes-Benz M278 Upper Intake Turbo Pipe
• Mercedes-Benz M278 Lower Intake Turbo Pipe

Tools

• Screwdriver

Procedure

1. Park the vehicle on level ground and set the parking brake.
2. Allow the engine to cool down.
3. Pull the hood release under the dashboard and open the hood.
4. Remove the top turbo pipe (air filter to turbo) using a screwdriver to loosen the upper clamp retaining screws.
5. Loosen the lower retaining clamp by using a screwdriver. Once lost, you may pull the pipe.
6. Remove the lower turbo pipe (turbo to intake manifold) using a screwdriver to loosen the pipe’s upper retaining screws.
7. Loosen the lower retaining clamp using a screwdriver; pull the pipe forward to remove it once loose.
8. Install the lower turbo pipe by loosening the lower clamp using a screwdriver.
9. Push in the top first, insert the bottom part, and push.
10. Tighten the upper screws. 
11. Tighten the lower clamp screw.
12. To install the Top pipe, insert the pipe bottom first.
13. Line up the Top pipe’s lowest part with the turbo inlet.
14. Position the top turbo pipe bottom first, then the upper part, then push.
15. Fasten the clamp at the bottom using a screwdriver.
16. Fasten the upper part retaining screws.

Applications

Mercedes-Benz vehicles are equipped with M278 engines.

M278 engines

• 2011 to 2017 S 500/S 550
• 2011 to 2014 CL 500/CL 550
• 2015 to 2017 S 500 Coupé/S 550 Coupé
• 2011 to 2018 CLS 500/CLS 550
• 2012 to 2020 SL 500/SL 550
• 2012 to 2014 E 500/E 550
• 2012 to 2014 ML 500/ML 550
• 2013 to 2014 GL 450
• 2013 to 2019 GL 500/GLS 500/GL 550/GLS 550
• 2016 to present BAIC BJ90 (an SUV from Chinese brand BAIC based on the second generation Mercedes-Benz GL-Class)

Check these troubleshooting and repair guides for more help on your Mercedes-Benz.

Frequently Asked Questions

Can you drive a Mercedes with a cracked turbo intake pipe?

It is not recommended. The engine can run lean and lose power, and unfiltered air and dirt can be drawn into the turbochargers and cylinders.

How do I know my turbo intake pipe is bad?

Poor acceleration, worse fuel economy, a whistling or hissing sound under boost, and lean codes P0171 or P0174 are common signs. Look for visible cracks in the plastic pipes.

Which engine does this guide cover?

The Mercedes-Benz M278 4.6L twin turbo V8 used in models such as the S550, E550, CLS550, GL550 and ML550.

Do I need special tools?

No. A screwdriver to loosen the hose clamps is enough for most of the job.

Related Guides

• Mercedes Turbo Supercharger Wastegate Solenoid Replacement
• Mercedes-Benz M274 M270 Spark Plug Replacement | 2.0L Turbo

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