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Pelican Technical Article:

BMW Intake
Manifold Removal

Difficulty Level: 5
Difficulty scale: Adding air to your tires is level one
Rebuilding a BMW Motor is level ten

   

 

This article is one in a series that have been released in conjunction with Wayne's new book, 101 Performance Projects for Your BMW 3 Series.  The book contains 272 pages of full color projects detailing everything from performance mods to timing the camshafts.   With more than 650+ full-color glossy photos accompanying extensive step-by-step procedures, this book is required reading in any 3 Series owner's collection. The book was released in August 2006, and is available for ordering now. See The Official Book Website for more details.

[click to enlarge]

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BMW E36 (1992-2000)

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BMW E30 (1982-1991)

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     Let me start off by congratulating the BMW engineers for squeezing the E36 six-cylinder engine into an almost impossibly tight spot. It is quite a remarkable packaging job, considering they did it in the early 1990s when all they had were computers with 386 processors and rudimentary 2D CAD programs. Yet their success makes it a big pain for mechanics who work on these carsóitís a tight squeeze, and you have to remove a lot of stuff to remove the intake manifold.

     The best way to learn how to remove the intake manifold is to carefully follow along with these pictures. This task includes one of the steps in the head gasket replacement (Project 17), so a number of other items have already been removed (fan, radiator, belts, etc.). If youíre just pulling the intake manifold, you donít need to remove these other items.

     For this project, I strongly recommend that you get a digital camera and take about a hundred photos of the disassembly process. If you have any questions as to how it was put together beforehand, you can easily refer back to the photos. As an additional resource, the companion CD-ROM to this book (available at www.101Projects.com) contains approximately 300 more photos of the manifold removal and installation process.

     Before you begin, let the car sit for about six hours before working on it. The pressure in the fuel lines should have dissipated somewhat, and the car should be stone cold while youíre working on it. Disconnect the battery (see Project 84), as you will be working very close to the starter, which has live current running to it at all times. You will also be disconnecting fuel lines near this connection and donít want to risk any sparks. Additionally, remove the gas cap from the gas tank to relieve any pressure that may have built up inside the tank from expanding fumes.

     Since installation is simply the reverse of removal, just hook everything back upóbut carefully inspect the intake boot for cracks prior to doing so. Consider replacing the intake boot while youíre in there, as it may start to crack and break once youíve disturbed it. Also, watch out for the lower rear manifold mounting bracket, as it can be very difficult to reattach (see Photo 4).

     If you would like to see more technical articles like this one, please continue to support Pelican Parts with all your parts needs.  If you like what you see here, then please visit our online BMW catalog and help support the collection and creating of new and informative technical articles like this one.  Your continued support directly affects the expansion and existence of this site and technical articles like this one.  As always, if you have any questions or comments about this helpful article, please drop us a line.

Figure
Figure 1
The air filter housing. The blue arrow points to the air intake channel that feeds the air filter. Remove the air filter housing and this channel by disconnecting it at the clips (orange arrows).
Figure
Figure 2
The throttle body and mass airflow sensor assembly are shown here. The two hoses located below that assembly need to be disconnected (orange arrow). Disconnect the electrical harness to the airflow sensor so you can move the sensor around easier (blue arrow). Disconnect the rubber boot from the sensor and the throttle body by releasing the clamps (yellow arrows). Check this boot carefully, as it often cracks and can cause erratic idling if it does. Disconnect the throttle body from the intake manifold (top two with the red arrows). At this point, you should be able to pull away the throttle body. Also, disconnect the vacuum hose that supplies the brake booster (green arrow), and detach the oil dip stick guide tube and the vent hose at the base of the dip stick.
Figure
Figure 3
Be careful of the throttle body cables when you detach the throttle body, as you donít want to twist or damage them. Also, do not disconnect the hoses that connect to the throttle body from underneath.
Figure
Figure 4

Disconnect the two fuel lines that circulate fuel through the injector rail. Carefully disconnect the clamps from the pipes that exit out of the bottom of the manifold (blue arrows). For S52/M52 engines, you may need special BMW tool 16-1-050 to release these fuel lines (purple arrows). Thereís also a clamp that holds the two metal lines underneath the manifold. Remove this clamp as well (look down the tunnel under the manifold for access). When reinstalling the manifold, the most frustrating attachment point was the bracket shown by the yellow arrow (remove this bolt after you have disconnected the fuel lines). A single bolt fastens the bottom of the manifold to this bracket, but getting that bolt threaded back into the hole was very difficult, because you canít see if the manifold is aligned with the bracket (misaligned in the photo). Use a small inspection mirror and an assistant to help you guide the bolt back into its proper place in the manifold. Thereís a similar bolt and bracket combination toward the front of the car.

Figure
Figure 5
This photo shows a close-up of the fuel injector plugs after the harness has been removed. The valve cover breather hose (yellow arrows) must be disconnected. The rearmost intake manifold nuts (inset) can be difficult to get to, so I recommend using swivel sockets for this task (see Photo 1 of Project 49).
Figure
Figure 6
To remove the intake manifold, you need to remove the engine wire harness first and slide it out of the way. Start by unscrewing the main plugs (green arrows, lower right). Then, loosen the main wire junction box (blue arrow) by lifting up the rain tray under the wipers and removing the two small screws contained within (red arrow, upper right). Let the harness hang looseóyou will need to push it out of the way when you lift out the manifold. Even more annoying than removing the wire harness, you need to disconnect a hosethat is located underneath the manifold, inside the tunnel below the plastic manifold runners (yellow arrow). Reach in and disconnect the plastic clip on the hose. It was a tight squeeze for my hand, so you may need to ask someone with small hands for help. The purple arrow shows the fuel injector wire harness pushed off to the side.
Figure
Figure 7
With everything disconnected, the manifold should lift up out of the engine compartment but not without a fight. The manifold is tightly squeezed in between the cylinder head and the firewall (near the wipers). You will have to wrestle with it a bit to get it off the studs that attach it to the cylinder head. Double- and triple-check your connections to make sure you didnít forget to disconnect a hose or line.
Figure
Figure 8

While you have the intake manifold apart, you should replace a few important seals. The first is the throttle body seal, shown on the right. It seals the throttle body housing to the intake manifold. A leak in this gasket can cause poor running and an erratic idle. On the left, one of the manifold-to-head gaskets is shown. These gaskets can also cause erratic engine performance if there are leaks around them. If the seal is breached, it will create a vacuum leak, and the engine may suck in additional air on the intake stroke, altering the air/fuel mixture ratio for that particular cylinder.

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