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Pelican Technical Article:

Intake Manifold Removal

Steve Vernon

Time:

4 hours4 hrs

Tab:

$10

Talent:

***

Tools:

T30 Torx, E10 Torx, 17mm wrench, small flathead screwdriver

Applicable Models:

Mercedes-Benz C350 (2008-14)
Mercedes-Benz GLK350 (2010-14)

Parts Required:

Gaskets, white lithium grease, O-rings

Hot Tip:

Clean around the runners before removing

Performance Gain:

Fix problems with the manifold

Complementary Modification:

Replace worn out hoses

There are several common problems that need to be eventually fixed with the EGR and swirl flaps on the Mercedes intake manifold. Unfortunately, you need to remove the complete manifold to access the repairs.

While it is possible to remove the intake manifold without removing the injectors and fuel rail it is only a few extra steps to pull the injectors. Doing so will give you a little more room and less things for the wiring to get hung up on when you are removing the manifold. If you want to leave the injectors in place simply skip the step of pulling the rail and injectors.

If you are going to be opening the fuel line on the motor the first step is to prep the car. I like to tell people to pull the fuel pump relay and then try to start the car. The car will turn over and then die. Do this about two to three times. Doing so will help drain excess fuel out of your system. Also open the gas cap to help depressurize the system. Then, make sure that the car has cooled down; you don't want to be working with gasoline when the car is hot.

Have a fire extinguisher handy. There will be some spillage of fuel as it's nearly impossible to prevent. Also, wear chemical resistant gloves if you don't want to get any gasoline on your hands, and make sure that you have plenty of paper towels or rags to help you clean up. Perform the injector removal in a clear, open, and well-ventilated space. It may not hurt to have an assistant around in case there are any problems.

You are going to be pulling the injectors out from the manifold so make sure to clean around the area and blow it out with compressed air so you do not get dirt down into the injector openings.

You will need to remove the front (red arrow) and rear (yellow arrow) engine covers along with the air ducts (green arrows).
Figure 1

You will need to remove the front (red arrow) and rear (yellow arrow) engine covers along with the air ducts (green arrows). Please see our article on engine cover removal for additional assistance.

The fuel rail and injectors are located on both the left and right side of the intake manifold and partially hidden by the wiring loom and EGR hoses (red arrows).
Figure 2

The fuel rail and injectors are located on both the left and right side of the intake manifold and partially hidden by the wiring loom and EGR hoses (red arrows). The fuel rail is a single piece and connected by a piece of pipe that runs along the rear of the ECU unit.

To remove the rail and injector begin by disconnecting the two wiring connections on the left side of the motor (red arrows) and slipping the harness of the fuel rail (yellow arrow).
Figure 3

To remove the rail and injector begin by disconnecting the two wiring connections on the left side of the motor (red arrows) and slipping the harness of the fuel rail (yellow arrow).

Pull back on the wiring bracket on the right side only for the connection to the ECU (red arrow).
Figure 4

Pull back on the wiring bracket on the right side only for the connection to the ECU (red arrow). This will separate the wiring connection.

Tilt the EU back out of the way with the left side wiring connection still attached (red arrow).
Figure 5

Tilt the EU back out of the way with the left side wiring connection still attached (red arrow). Use a T30 Torx and remove the ECU mount on the right side of the intake manifold (yellow arrows).

Use an E10 Torx and remove the fasteners holding the wiring loom in place (red arrows) on the right side valve cover.
Figure 6

Use an E10 Torx and remove the fasteners holding the wiring loom in place (red arrows) on the right side valve cover. Use a T30 Torx and remove the single Torx screw connecting the wiring loom harness to the intake manifold (yellow arrow).

Disconnect the wiring from the coils by using a small screwdriver and pushing the clip back and then gently squeezing the clip and sliding the connections off (red arrow).
Figure 7

Disconnect the wiring from the coils by using a small screwdriver and pushing the clip back and then gently squeezing the clip and sliding the connections off (red arrow).

Use an E10 Torx and remove the bolt holding the ground wire in place (red arrow).
Figure 8

Use an E10 Torx and remove the bolt holding the ground wire in place (red arrow).

Continue to use the T30 Torx and remove the two screws holding the wiring harness bracket from the rear of the motor (red arrows).
Figure 9

Continue to use the T30 Torx and remove the two screws holding the wiring harness bracket from the rear of the motor (red arrows).

Disconnect the wiring from the air pump (red arrow).
Figure 10

Disconnect the wiring from the air pump (red arrow).

Remove all the electrical connections from the front of the right side cylinder head (red arrows), and move the wiring harness off to the side.
Figure 11

Remove all the electrical connections from the front of the right side cylinder head (red arrows), and move the wiring harness off to the side.

Use an E10 Torx and remove the wiring harness connectors from the left side bank (red arrows), including the one on the lift eye on the rear.
Figure 12

Use an E10 Torx and remove the wiring harness connectors from the left side bank (red arrows), including the one on the lift eye on the rear.

Next, remove the two T30 Torx screws (red arrows) holding the left side ECU bracket and release the EGR hose from underneath it (yellow arrow).
Figure 13

Next, remove the two T30 Torx screws (red arrows) holding the left side ECU bracket and release the EGR hose from underneath it (yellow arrow).

Pull the EGR hose from the top of the throttle body (red arrow) and move the hose out of the way.
Figure 14

Pull the EGR hose from the top of the throttle body (red arrow) and move the hose out of the way.

The connections for the injectors are small, can be brittle and in a tight spot.
Figure 15

The connections for the injectors are small, can be brittle and in a tight spot. Use a small flathead screwdriver and pop up the gray clips (red arrow) and then gently squeeze the clips and pull the connections off each injector.

Even though the engine should have been sitting overnight and you have removed the fuel pump relay to try and get the fuel out of the rail there will still be some.
Figure 16

Even though the engine should have been sitting overnight and you have removed the fuel pump relay to try and get the fuel out of the rail there will still be some. Unscrew the Schrader valve cap and wrap a screwdriver in a rag and press in the end of the Schrader valve (red arrow). This will release the remaining pressure in the system. Gas will come out so be prepared to catch and dispose of it according to the regulations in your area.

Use a 17mm wrench and separate the fuel line from the distribution rail (red arrow).
Figure 17

Use a 17mm wrench and separate the fuel line from the distribution rail (red arrow). Some fuel will come out so be prepared to catch and dispose of it according to the regulations in your area.

Remove the four E10 Torx bolts holding the fuel rail to the intake manifold (red arrows).
Figure 18

Remove the four E10 Torx bolts holding the fuel rail to the intake manifold (red arrows).

You can now pull the fuel distribution rail out from the manifold.
Figure 19

You can now pull the fuel distribution rail out from the manifold. The rail is just held in place by the six O-rings between the injectors and manifold so you should just be able to wiggle and pull it straight up.

Immediately plug the injector openings with a clean rag or paper towel.
Figure 20

Immediately plug the injector openings with a clean rag or paper towel. The opening leads directly to the combustion chamber, and you do not want anything falling in there (red arrows).

If you do pull the injectors you must replace the O-ring on the lower part of the injectors (red arrow).
Figure 21

If you do pull the injectors you must replace the O-ring on the lower part of the injectors (red arrow). If you do not separate the injectors from the rail you do not need to replace the upper O-ring. Apply a little white lithium grease when reinstalling the injectors back into the manifold.

Disconnect the wiring connection (red arrow) from the tumble flap sensor (yellow arrow).
Figure 22

Disconnect the wiring connection (red arrow) from the tumble flap sensor (yellow arrow). There is a small gray tab that faces the rear of the vehicle. Use a small flathead screwdriver and lift the tab up and then gently squeeze the tab and separate the connection.

Separate the wiring connection on the tumble flap sensor on the left rear section of the manifold (red arrow).
Figure 23

Separate the wiring connection on the tumble flap sensor on the left rear section of the manifold (red arrow).

Reach down under the throttle body and separate the wiring connection (red arrow) for the throttle.
Figure 24

Reach down under the throttle body and separate the wiring connection (red arrow) for the throttle.

Make sure to clean the area around the intake runners as best you can.
Figure 25

Make sure to clean the area around the intake runners as best you can. Over time a lot of dirt and debris can accumulate there, and you do not want it falling into the intake ports.

Use an E10 socket and remove the eight bolts holding the manifold to the motor (red arrows).
Figure 26

Use an E10 socket and remove the eight bolts holding the manifold to the motor (red arrows).

Lift up the front of the intake and separate the two lines going into the manifold (red arrows).
Figure 27

Lift up the front of the intake and separate the two lines going into the manifold (red arrows). Use a small flathead screwdriver and gently pry the hoses back out from the clips.

With the hoses free you can lift the manifold up and out from the engine.
Figure 28

With the hoses free you can lift the manifold up and out from the engine. Immediately place some rags or paper towels into the intake ports to prevent anything from falling into the ports (red arrows).

You can now address the issues with your intake manifold as well as replace the knock sensors.
Figure 29

You can now address the issues with your intake manifold as well as replace the knock sensors. Installation is the reverse of removal. Do not forget to install new gaskets.


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Page last updated: Wed 12/7/2016 02:56:54 AM