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.
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 cars—it’s 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 you’re just pulling the intake manifold, you don’t 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 you’re 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 don’t 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 up—but carefully inspect the intake boot for cracks prior to doing so. Consider replacing the intake boot while you’re in there, as it may start to crack and break once you’ve disturbed it. Also, watch out for the lower rear manifold mounting bracket, as it can be very difficult to reattach (see Photo 4).
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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).
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.
Be careful of the throttle body cables when you detach the throttle body, as you don’t want to twist or damage them. Also, do not disconnect the hoses that connect to the throttle body from underneath.
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). There’s 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 can’t 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. There’s a similar bolt and bracket combination toward the front of the car.
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).
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 loose—you 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.
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 didn’t forget to disconnect a hose or line.
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.
Comments: I had to change the clutch on my sons' 2006, 330cic.
Which I did. After putting it all together, It started and idled, but the drive by wire throttle seems to be inoperative.
I am looking for wiring diagrams and advice.
I thank you in advance.
May 16, 2013
Comments: Are the hoses indicated by the orange arrow in Figure 2. supposed to have coolant in them? I have an aftermarket CAI on my car from the PO, and as I disconnect the hoses that looked like the indicated ones, coolant started to pour out...
May 12, 2013
Comments: any idea where this hose goes? Cant find it in 101 projects book nor in the bentley book
August 12, 2012
Followup from the Pelican Staff: There should be a fitting with two small nipples and one large, if I remember correctly. It connect to one of the small nipples. - Nick at Pelican Parts
Comments: hey wayne, I have a 94 320i, when I am giving it some gas around 800 to 3k sometimes intermittent it feels like its missing. my flugs are ok but here is the thing. I am not sure of my engine...hahaha because the plugs in there and the plugs I got from BMW and from NAPA are different to the ones in now. my question is, if the plug is a little two short and two prong not 4, will this cause issues? I dont want to put the slightly longer plugs in with 4 prongs the ones sugested because I am afraid they might slap. Rob
July 17, 2012
Followup from the Pelican Staff: Yes, you have to use the correct plug in your engine. The electrode and insulator length determine resistance and temp range. Try the correct spark plugs and see how it runs, - Nick at Pelican Parts
Comments: Image #6 does not seem to match my 1998 M3 engine. How do I take off the fuel injector harness? I have taken off the two nuts that hold the fuel injector harness/assembly to the intake manifold, but it does not come off. How do I unplug the fuel injectors?
July 16, 2012
Followup from the Pelican Staff: There are small wire clips at the top of the fuel injectors. I like to use a small pick, working at top of injector electrical connector, and disconnect the wire clips on each side. It can be a pain and sometimes the clip will reconnect when you are lifting harness. - Nick at Pelican Parts
Comments: Causes for faint knocking at 70mph in 5th when going up slight grade even with 93 oct Fuel. Lugging at lower rpms will induce strong knock. Seems to have started after vanos rebuild. Vanos is now quiet and engine responds normally at all ranges, mileage is normal. One annoyance is engine revs to 2-3k at cold start. Knock sensors are original. 1995 325i, 155000 mi. Thanks
March 15, 2012
Followup from the Pelican Staff: I would check for fault codes, then inspect the fuel system and see if the engine is running lean. If everything checks out there, you could have a carboning problem. - Nick at Pelican Parts
Comments: Hi Wayne. After replacing my f shape cooling pipe, i found that the nipple at the front of the engine behind the vanos that i connect too has some rot holes in it.It appears to be steel and i want to know if this nipple is replaceable, or do i pratley steel repair the hole instead?
March 5, 2012
Followup from the Pelican Staff: I believe that nipple is pressed in and not serviceable. A machien shop may be able to replace it for if you cannot repair it yourself. - Nick at Pelican Parts
Comments: Wayne, 2 projects I'm contemplating - 1 replace all the coolant hoses, and 2 replace the rubber fuel lines while I'm in there. Any hints as far as tricks to these? The manifold removal looks like something I only want to do once! Thanks for all your great work here for the DIYer.
'97 BMW 328i, standard with 174k miles
January 21, 2012
Followup from the Pelican Staff: The best advice I can give is to read the procedure before beginning and be sure toy have all the parts you need on hand once you start the repair. Inspect any plastic lines and see if they feel brittle, sometimes something will break just touching it, leaving with you unable to complete the repair while you wait for parts. - Nick at Pelican Parts
Comments: I had a friend witch is a mechanic tear apart my 325i L6 engine to replace the starter. He did put the starter back on but has not been back to finish the job. I have been thankful for this being available to thise in need. And right now I am one of them due to not having all the answers I need to finish. I did put the engine back together but I a problem. When I start the engine it is ok, but when I give it gas, it goes up and down on its own. Then it will just stop on its owm and now I am not sure what it is that is causing this. I was told to check all my vacuum lines which I have and I can not see any thing. Also, is the torque specs for the intake manifold 20.7 ft lbs, and what is the tightening order for the intake manifold nuts. Also, you show great pictures of a lot of parts and thier location but a few I have noticed, like I know that the breather hose goes to the valve cover, but where does the other end connect to. And the canisters on the driver front wheel side, the one has two vacuum hoses connected to it on the top and there is one on the bottom that is not hooked up to anything. I even have two coolant lines that just have bolts in them and clamped. I have seen them hooked up to what looks like a coolant sensor. I did look to see if I had a spot for what I have seen, but I do not. All in all, this site has been very helpful and I hope that my questions will bring you to show pictures on all the hose hookups. Thank you and keep up the grat job you have done so far.
July 30, 2011
Followup from the Pelican Staff: Is the check engine light ON? There may be fault codes that will point you to the cause of the poor running problem. The breather hose connects to the intake manifold, (educated guess not knowing what year your vehicle is).- Nick at Pelican Parts
Comments: I am looking for the torque specs for tightening the intake manifold and is there a sequence??
July 26, 2011
Followup from the Pelican Staff: M6 bolts 10 Nm
M7 bolts 15 NM
M8 bolts 22 Nm
Start in the center of the inake manifold and work your way out in a criss-cross pattern.
- Nick at Pelican Parts
Comments: does anyone have a better photo for the location of the lower bolt to remove the intake manifold, I have been trying to find that damn thing for 3 days. I have the Haynes manual but the picture is too tight for me to figure out where the bolt is, and I think that photo is from the underside of the car.
July 19, 2011
Followup from the Pelican Staff: If you feel around under the intake manifold, you will find a bracket with a fastener. You will have to remove the fastener. I can be more specific if I knew the year of your vehicle. - Nick at Pelican Parts
Comments: at 248,680 miles I blew one of the hose connectors for the heater core. Ordered the flange, just over 10 bucks from Pelican. Was dreading the intake removal, but in all honesty it only took just over an hour the first time. After reassembly, I was missing the rear fuel line clamp, so in fear that it dropped into the intake I took it all apart again, this time in about 40 mins. The rear intake nut was hard to get to at first but then I found that if I spread the wires connectors just wide enough a straight shot with a long extension and once it's loosened my hand could reach it if i squeezed my eyes shut really tight. Heads up though, if you replace your flange the screw that goes down to the heater core may come out along with the nut that holds the flange on, be sure you put that screw back into the heater core first then the flange then the nut, as the flange is plastic and it's easy to overtighten if you put the nut and screw together on the flange and then try to tighten down to the heater core, if that's confusing you'll see what I mean if you have to replace one. Also just as important and lastly, make sure to order the 3 .50 cent rubber orings that go along with it. I want to make a Youtube video of this swap so bad. btw i found my fuel line clamp under the car when I moved it. The hardest part of this job is actually bleeding the coolant system. Next week I'm replacing the water pump simply because it's never been done on this vehicle. Now on to 300,000 miles!
February 3, 2011
Followup from the Pelican Staff: Thanks for the tips here, let us know if you do create that video - post the link here in the forums! thx - Wayne at Pelican Parts
Comments: What is BMW tool 16-1-050? Do i really need this to remove the fuel lines figure 4, purple arrows? Search on Pelican with no result. My is 96 328i.
November 2, 2010
Followup from the Pelican Staff: I'm actually not sure - that was a reference that was printed in the factory documentation. The tool is available from Pelican via special order (we would get it direct from BMW). - Wayne at Pelican Parts
Comments: I understand I have to remove the intake manifold to replace my knock sensors. I read the code from my check engine light and it was 1286, which is telling me my knock sensors are bad. There is no DIY for an E36 pre 95 and I drive a 93 318i how major of a job would it be to replace the knock sensors and will it be different from the DIY post from someone who drove a 95 M3?
August 11, 2010
Followup from the Pelican Staff: See the article on the replacement of the head gasket. The knock sensors are shown on there. For the four-cylinder cars, I believe the procedure is similar - it's indeed a pain to reach them. - Wayne at Pelican Parts
Comments: You got me interested, You said not to disconnect the hoses beneath the Throttle body why is that?
May 25, 2010
Followup from the Pelican Staff: They are full of coolant, and you don't need to disconnect them unless you're taking the throttle body out of the car. The throttle body is connected with the cruise control and throttle cable too, and disconnecting those are a pain as well. - Wayne at Pelican Parts
Comments: There are tons of DIY's for 3 and 5 series. Step up to the plate and take a swing at a 7 series, e65 or e66.
May 4, 2010
Followup from the Pelican Staff: We're working on it soon! - Wayne at Pelican Parts
Comments: Wayne: You have some great photos of the E36 intake manifold removal project. I have the alternator off of a 1996 328is and can see that I can also get to the vanos oil line pretty easily now and also have to replace the cam position sensor. I think I can get to the CPS connector without taking the intake manifold off but a photo of where the connector is and what it looks like with the manifold off would be very helpful in guiding my hands. Does it appear in any of the bonus photos?
January 23, 2010
Followup from the Pelican Staff: You can see the coolant temperature sensor here: http://www.101projects.com/BMW/Projects/012/images/DSC05478.JPG it is below the second intake manifold port. - Nick at Pelican Parts
Comments: Wayne, do you have any directions or information on replacing the intake manifold non-return valve cyclone valve? I have a 97 528i and a 2003 325cic. Thank you, Dave
Comments: Just done a cooling system overhaul on my E36,which intailed removing inlet manifold,sence reassemble I have rough idle,hard to start,once driving its ok.Do I need to bleed the fuel system.
November 24, 2009
Followup from the Pelican Staff: The fuel system is self-bleeding, you do not have to bleed it. I would check for vacuum leaks, a disconnected vaccum hose or cracked or damaged line. It's also a good ide to check the vehicle for fault codes. - Nick at Pelican Parts
Comments: I had to replace my 'F' shaped heater hose $83 mind you and I had to remove the intake manifold. After replacing everything, the vehicle runs very rough for a few seconds then shoots up to about 4k RPM. What could be causing that? I had to remove a hose from the throttle body because it is on the 'F' shaped heater hose.
October 8, 2009
Followup from the Pelican Staff: I would check all the hoses to make sure they are attached securely. Check the system for vacuum leaks, as what you are describing is a classic symptom of a big vacuum leak. - Wayne at Pelican Parts
Comments: I was really struggling with moving the wire harness out of the way until I realized you need to remove the "rain tray" that the black junction box was screwed into. Remove 2 screws on each side, and it basically just lifts out after a little gentle persuasion. Then you get much better access to the back of the manifold, especially that last nut. A swivel socket and a simple 6" extension did the trick to get that nut out.
Now, I need to figure out how to disconnect the fuel lines using that special tool. It appears that the fuel line from the injector rail disconnects at the back of the manifold using those quick connectors. It's hard to see back there, so any advise is welcome.
September 19, 2009
Followup from the Pelican Staff: See this article here: http://www.pelicanparts.com/bmw/techarticles/E36-Injector-Replacement/E36-Injector-Replacement.htm ">http://www.pelicanparts.com/bmw/techarticles/E36-Injector-Replacement/E36-Injector-Replacement.htm">http://www.pelicanparts.com/bmw/techarticles/E36-Injector-Replacement/E36-Injector-Replacement.htm You don't need any special tools, the fuel lines come off with the manifold. In particular, see Figure 15 of that article. - Wayne at Pelican Parts
Comments: One other comment be careful when removing the manifold because it's easy to break the skinny vacume lines especially the ridgid one the runs from the fuel pressure regulator the soft part on the end where it connects to the intake manifold gets brittle and sometimes breaks when you try to pull it off. I fixed mine by slidding 3/16 flexible vacume line over the ridgid line about two inches down, after I coated the id lightly with sealant goop then I wrapped about three tiny zip ties around it. Before I hooked it back up, I tested it with a hand held vacume pump to make sure it pulled vacume.
August 21, 2009
Followup from the Pelican Staff: Thanks for the additional info. Working with older plastic parts you have to be delicate. Heat and oil contamination cause them to become brittle, just as you noted.- Nick at Pelican Parts
Comments: Hey Wayne,
I just switched my manifold to an OBD1 model and it's the best thing I ever did for my 97 328i, it really zooms past 3000 rpms now.
When removing the manifold I would recommend replacing all the vacuum lines you can especially if the car is over ten years old. Just buy a few feet of 3/16 bulk line and replace it one section at a time so you don't get disorientated. I also used dabs of different colored paints to color code the electrical connectors because tape gets smeared and dirty.
August 21, 2009
Followup from the Pelican Staff: - Wayne at Pelican Parts
Comments: Wayne, I have every tool imaginable including swivel sockets and I cannot get a socket on it. I have 92 e36 birth year of e36 and I am telling you I have tried everything to get to it except for pulling the engine. I have owned 1986 320i, 2000 M5, 92 325i, and 2001 740il and I have always relied on my mechanical ability on all these cars. through the years and have never had a problem like this. I must admit this is a first for me seeing poor engineering on a German car. Ooops, I take that back. Try replacing the Blower fan motor in the e36....totally sucks!
Was there a change in the position of the motor in later e36 models? Any other ideas????
August 11, 2009
Followup from the Pelican Staff: Send me some pictures, email@example.com and I'll take a look. - Wayne at Pelican Parts
Comments: I need to replace Idle Control Valve which is located under intake manifold but I have run into a problem. The last or first of the seven bolts which is located up next to the firewall. I cannot get a socket on the bolt. Any ideas tips or tricks to get to it? I also want to replace all the hoses under the intake manifold while I am in there as well as power wash. Love Pelican Parts articles and support, Thanks
August 10, 2009
Followup from the Pelican Staff: All of the bolts are indeed accessible - if you have the right tools. I think that you might need a 1/4" set of swivel sockets to reach in there. In the first section of my book, I review the "essentials" which I think everyone should have in their toolbox. The swivels are in there, just for jobs like these. Hope this helps... - Wayne at Pelican Parts
Comments: where can i connect my breather hose and the small hose that coming from the cylinder head? somehow its been disconnected and i had no clue where should i put them back...thanks for the help.
August 5, 2009
Followup from the Pelican Staff: You'll have to post a picture for me to be able to adequately help you. Thx. - Wayne at Pelican Parts
Comments: Can the camshaft position sensor on the 318ti be removed more easily than the 6 cylinder without dis-assembly of the intake?
June 19, 2009
Followup from the Pelican Staff: Yes, the cam position sensor is relatively easy to access on the front of the 318 engine. I think the plug for it might be hidden underneath the manifold though. - Wayne at Pelican Parts
Comments: Figure 6 shows the hose that is located underneath the manifold indicated by yellow arrow. There is another rubber hose underneath the manifold as well as another sensor. Can you tell me what they are for? Thanks
April 25, 2009
Followup from the Pelican Staff: If you look at the next photo (#7), you can see hoses running underneath there. Two small coolant hoses connect to the throttle body. The fuel lines run underneath there too. There's also a breather hose with a check valve on it that runs under there too.