A BMW N52 intake manifold removal is necessary for performing many repairs including vacuum leaks and starter motor replacement.
- Intake manifold gaskets - Always replace the six gaskets after removing the BMW N52 intake manifold. Reusing the old gaskets may cause a vacuum leak requiring the manifold to be removed from the vehicle again.
- Crankcase vent hose - The crankcase vent hose is actually a hard plastic pipe that runs from the oil separation valve on the bottom of the intake manifold to the valve cover. It is infamous for breaking during intake manifold removal causing a nasty vacuum leak and a rough idling engine. It should be considered an expendable part like the manifold gaskets and be replaced every time the manifold is removed. Please see our parts list below for ordering.
- Return pipe - Like the crankcase vent hose, the return pipe is connected to the oil separation valve and is prone to breaking during intake manifold removal. We strongly recommend having a replacement ready when doing this repair. Please see our parts list below for more information.
The following steps were performed using a 2006 530xi. There were many different models produced with the N52 engine. Some of these steps may vary depending on the model.
- ALWAYS disconnect the negative terminal from the battery before starting this repair. Since you will be using tools around the engine compartment battery terminals, it is very easy to create a short circuit and destroy sensitive electronics. Play it safe - take a couple of minutes to disconnect the power!
- Begin by removing the cabin filter cover by pressing the side tab and sliding the cover off.
- Use a flat blade screwdriver and an 13mm socket to remove the cabin filter containers.
- Next, remove the right air inlet.
- Repeat above steps with right cabin filter container and air inlet. Note that most models will need to have the hood switch removed from the right cabin filter container.
- Remove the engine cover(s) from vehicle.
- Remove the lid from the intake muffler (air filter housing) . In most models, the lid is held in place with plastic latches.
- Using a metal pick, GENTLY lift the plastic retaining tab on the mass air flow sensor plug. Unplug the mass air flow sensor.
- Use a flat blade screwdriver to loosen the hose clamp securing the intake pipe to the intake muffler lid.
- Remove the lid and the mass air flow sensor from the vehicle.
- Next, the intake pipe needs to be removed from the throttle body. Begin by loosening the hose clamp where the intake pipe is attached to the throttle body. Pull the intake pipe loose and remove any vacuum lines attached to it. We strongly recommend marking any loose connections like vacuum lines with a high visibility tape - this helps avoid missing any connections during reassembly.
- Remove the wiring harness and its plastic mounting bracket from the strut brace. It is usually attached with two plastic rivets as shown below.
- The strut brace is held in place with four torx bolts. These bolts strip very easily and can be expensive to replace! If you do strip one, please click here for an affordable alternative to the expensive factory replacements.
- Use a couple of bungee cords to secure the wiring harnesses out of the work area.
- Begin by unplugging the differential pressure sensor from the rear of the intake manifold.
- Unplug the outer DISA valve (adjuster unit).
- Remove the cap from the fuel rail Schrader valve. Using a small screwdriver, depress the Schrader valve to release the fuel pressure in the fuel rail. We suggest putting a rag under the valve to catch the small amount of fuel that may leak out.
- Disconnect the fuel line from the fuel rail by releasing the plastic locking collar and pulling the line free from the rail. Remove the fuel line from the back of the intake manifold and store it safely out of the work area.
- Using an 11mm socket, remove the three intake manifold mounting bolts that also anchor the fuel rail bracket. Use a 10mm socket to remove the two inner fuel rail bracket bolts. Remove the bracket from the vehicle.
- Unplug the throttle body.
- Disconnect the fuel tank vent valve.
- Unplug the oil pressure switch.
- Using an 11mm socket, remove the last four intake manifold fasteners.
- The next step requires disconnecting the crankcase return pipe from the oil pan. It requires reaching down behind the intake manifold, squeezing the return pipe connection, and pulling it loose. If you are planning on replacing the return pipe, do not waste time trying to remove it....just reach down and break it off with your hand.
- Disconnect the crankcase breather hose from the valve cover. Like the return pipe above, if you are planning on replacing the breather hose don't waste time trying to disconnect it...just break it off.
- Grasp the intake manifold and pull it loose from the cylinder head.
- Carefully rotate the intake manifold so the back can be accessed. Disconnect the PVC heating element.
- Locate the wiring harness on the bottom of the intake manifold. Using a 10mm socket, remove the two wiring harness mounting bolts.
- Unplug the inner DISA valve.
- Unplug the fuel tank vent valve sensor.
- Remove the fuel tank vent valve from the wiring harness bracket.
- Disconnect the wiring harness from the back of the intake manifold.
- Remove the intake manifold from the vehicle.
BMW N52 Intake Manifold Reassembly Checklist
***The following steps were performed on a 2006 530...other models may vary.- Plug the wiring harness back into the rear of the intake manifold.
- Install the fuel tank vent valve back onto the wiring harness and plug it back in.
- Plug the inner DISA valve back in.
- Reinstall the wiring harness. Torque the wiring harness mounting bolts to 10.5 Nm (8 ft-lb).
- Plug the PVC heating element back in.
- Carefully position the intake manifold back onto the cylinder head. Make sure not to pinch any of the gaskets.
- Attach the crankcase breather hose back onto the valve cover. Make sure to apply enough pressure until you hear it click into place on the fitting.
- Reach down behind the intake manifold and attach the return pipe back onto the oil pan. Once again, make sure to press on it until it clicks into place.
- Install the intake manifold fasteners and hand tighten them. DO NOT torque until the fuel rail bracket mounting bolts are installed below.
- Plug the oil pressure switch back in.
- Attach the fuel tank vent hose back together.
- Plug the throttle body back in.
- Reinstall the fuel rail bracket and hand tighten the mounting bolts.
- Starting from the middle and working your way out, torque the intake manifold bolts to 17 Nm (12 ft-lb).
- Plug the fuel line back in.
- Plug the outer DISA valve back in.
- Plug the differential pressure sensor back in.
- Reinstall the strut braces and torque the mounting bolts to 25 Nm (18 ft-lb).
- Reinstall the wiring harness bracket.
- Reinstall the intake boot and intake muffler lid.
- Reinstall the engine covers.
- Reinstall the cabin filter assembly.
- Reconnect the battery.