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-   -   Project M54 Engine: Intake manifold (http://forum.e46fanatics.com/showthread.php?t=901967)

jjrichar 02-07-2012 12:09 AM

Project M54 Engine: Intake manifold
9 Attachment(s)
Intake manifold

Link to other parts of the project

You may need to remove the intake manifold for a number of reasons. You may have a problem with the manifold, but most likely you have a problem with something that's underneath it. I've seen some DIYs (eg oil separator repairs) that avoid removing the manifold so that the intake manifold gasket doesn't need to be replaced. As far as gaskets are concerned, it's not a cheap one.

You may have seen some of the photos of the engine I'm pulling apart, and quite rightly concluded that it's had a difficult life. Most of the gaskets etc were completely shot. Interestingly, the intake manifold gasket on this engine was as fresh as a daisy. Flexible and rubbery like I would expect a new one to be. I would have no hesitation in re-using the gasket. I'm not someone who normally skimps on this sort of this, but in this case I would consider replacing the gasket that is on this engine as a waste of money.

One DIY I've seen described online was the replacing of the oil separator system. (Have a look at this engine for an idea of how it leaks). This sort of job is far easier with the manifold removed.

Also, after working on this engine (and my car at home), what is obvious to me is that disconnecting stuff and removing it so that you have room to do the job you want to is going to be more successful than not removing things that are in the way, and not having enough room. You are far more likely to break things by forcing it rather than removing it completely.

For example the large electrical harness that comes from the ECM and goes to all of the sensors/solenoids is designed so that each plug is unique. BMW are smart. They can't afford for their workers to put a plug in the wrong place when the car is assembled. The plugs only go in one place, and the wires are just the right length to go to the correct sensor. Mark them if you want to, but I just prefer to take a bunch of photos as I go. Don't be afraid to disconnect them and get it all out of the way.

As most are aware the engine sits on an angle, and as the intake manifold sits on the top, it collects a whole lot of rubbish around where it connects to the engine. This needs to be removed before you pull off the manifold. If you don't, lots of stuff that you don't want in places like the intake valve chamber will fall in there when you pull the manifold off.
My advice is:
- At the start, and after each step, get your air compressor gun in there and give it a blast to remove anything. A vacuum cleaner won't do the job properly.
- When a hole that you don't want anything to go in is exposed, immediately plug it with a shop rag.

Finally, you will pull off lots of nuts and bolts. When you drop them they can go in places where you won't find them again. Even with an engine that's out of the car, I dropped nuts and had to pull of engine mounting brackets etc to find them again. With the engine in the car, it would be even worse. My solution is this.


Like I said in my first post, I don't have a car to work on, just an engine. If you know of something that I've done here that's incorrect, or there's an omission please let me know.

This isn't for the faint hearted. There's nothing really difficult here, but a lot of stuff is going to get pulled off the engine. I use zip lock bags and immediately store and mark what it is.

In this first photo below the oil filter housing has been removed, but it doesn't need to be.

When you get to the stage in the photo, this is a good time to remove the fuel rail. You can't remove the nuts that hold on the intake manifold with the fuel injection harness in place (The rail can stay there if you want). Refer to the part of my project that is about the fuel injection rail.

You have two choices here:
1. Remove the fuel injection harness but leave the injectors in place. You can remove the manifold leaving the injectors connected to the manifold, but you will have to remove the fuel from the rail, and disconnect the rail from the flexible fuel hose at the rear of the manifold. Advantage: less chance of injector damage as they remain connected to the manifold.
2. Remove the injectors completely from the manifold and move to the side. Advantage: Don't have to
bleed the fuel from the rail.

Me, I would completely remove the injector rail and injectors, cover it up, and move it to the side where it can't get hurt.

To get to the stage below, lots of stuff has to be removed as it says in the photo. Make sure you disconnect the battery before you disconnect the positive terminal onto of the manifold.


I am personally going to remove the idle control valve and DISA valve at this stage. They don't need to be removed to get out the manifold, but it's easy to remove them, and there's less chance of them getting damaged later.

Now some things need to be disconnected at the front and rear.
At the rear is a vacuum outlet. It goes to two places (from the Y junction in the photo). One is the brake booster, and I don't know the other. I found removing the single OEM crimp clamp and removing both the hoses from the Y junction to be easiest.




Once this is done, remove the large bolt on the bracket underneath that supports the manifold. Also unclip and disconnect the knock sensors plug.



Now remove the 9 nuts that hold on the manifold at the top. In this picture you can see the fuel rail is still connected. However, if the fuel rail harness was still connected, you wouldn't have access to the manifold nuts.


This is what it looks like when it's off.


vimal32 02-07-2012 04:16 AM

Awesome write up.


flashmeow 02-07-2012 11:53 AM

you need to write for some BMW repair journals because you writting is that good!

SeanC 04-16-2012 01:22 PM

Do you have to remove alternator and/or oil filter housing for this job? Looks like they're already out of the way...

TurnersInOz 04-16-2012 04:18 PM

I read every one of your DIY's, just to learn. Your pictures and explanations are excellent, and I really appreciate you posting them for all to benefit from.


jjrichar 04-17-2012 06:46 AM

Regards the OFH and alternator question, the OFH can stay in place, but I don't know about the alternator. I suspect it also can stay in place. You should have sufficient access once all of the air ducting/mass air flow sensor/throttle etc are all removed.

phamine 04-29-2012 06:59 AM

Very nice diy

Infinitasbeemer 09-09-2012 12:17 PM


Originally Posted by SeanC (Post 14297848)
Do you have to remove alternator and/or oil filter housing for this job? Looks like they're already out of the way...

No.. I didnt have to remove those..

Imola.ZHP 10-05-2012 04:39 AM

Thanks for posting this!

Looks like I was only 10 bolts and a few extra hose clamps away from removing the manifold when I did my 100k maintenance at the end of last year. I bet replacing all of the hoses underneath it would have been much easier with it out of the way, especially that oil separator BS!

I am about to do my clutch and I've read that it is easier to get to the top transmission bolts by pulling the intake manifold first. Since I have pulled everything except the manifold itself, I wanted to check out a DIY to see how bad it would be...

I am confused though, you say to replace the manifold gaskets, then you say yours were ok. Maybe you just got lucky on this engine? Unfortunately, I failed to order an intake manifold gasket set from my parts supplier. Would a local (autozone, etc) supplier have this set? I am in Memphis, so we have both a BMW stealership and aftermarket parts suppliers, but I try to avoid the stealership at all costs...

Thanks again! I believe I will go ahead and pull the manifold to make the clutch job more easy, like I said, I've already removed everything you listed except for the actual manifold itself. 10 bolts and a few more hose clamps. I should be able to handle that...

jjrichar 10-05-2012 10:53 PM

With regard to the gaskets, I had assumed beforehand that I would need to replace them, as this is what all the literature says to do. However when the manifold came off, it was obvious that the gaskets were in very good condition, and could easily be re-used. I would suggest removing the manifold and see what condition your gaskets are in. If they are still soft and rubbery you should be able to use them again. If not (I don't live in the US), but I suspect your local generic auto parts shop won't have them. I hope this helps

eman1111 05-15-2013 03:03 PM

Great DIY write up, thank you. I'll be doing this work on my 2001 330i in the next couple of weeks to replace leaky heater/coolant lines. I've been working on cars as a shade-tree mechanic for about 30 years and I'm not afraid to dig-in to even complicated jobs. How much time should I expect to spend on this? Again, the reason I'm doing it is primarily to replace leaky coolant lines. While I'm in there I will replace the manifold gasket, temp sensor and any small vacuum lines that are worn out. I replaced all of the components of the oil separator system last year, but did it without removing the manifold. Incidentally, if I had to do it again I would probably remove the manifold. It's extremely difficult to get at some of those tubes and connections from the bottom. Especially with large hands.

jjrichar 05-15-2013 05:16 PM

I would give yourself 5-6 hours for the whole job. This is just a guess, as I did it in stages over a long period rather than starting from scratch and doing just this job. If you are going to be replacing stuff on spec just because it is accessible, you may want to consider changing the crank position sensor as well.

2003silver330i 05-25-2013 10:13 AM

I'm removing the intake on my 2003 330i as we speak and I do not see that bracket underneath the throttle body housing on my car. It is just a big empty area right there. Is it possible a previous owner removed it or was it phased out of the design on later models?

jjrichar 05-26-2013 05:52 PM

I suspect someone has removed it. I had a quick look on realoem.com and the 2003 engine had the bracket. All M54 engines that I looked at had the bracket.

If you have the intake manifold out, I would get the bracket and put it on. It's not expensive. There's a lot of weight on the manifold with the throttle, ICV, etc all attached, and when only connected at the top, I suspect the manifold might crack after a while.

jjrichar 06-30-2013 07:45 PM

Update: I did this job this weekend to change the oil separator. Some of the stuff I had written above was a little off the mark.

1. You don't have to remove the fan or alternator. Unbolt the power steering reservoir and lie it to the side. All of the air box, MAF sensor, etc obviously needs to come out.
2. There are a number of cables etc that are zip tied to the back of the manifold. You will need to release these.
3. The knock sensor clip is difficult to get to. Initially pull the manifold off about 2 inches and then get your hand down there and release it. You don't have to unplug it. When installing, put the intake manifold in the engine bay about 2 inches short of installing, connect the plug to the clip, then install the manifold.
4. I removed the cables that go over the top of the engine to make it easier. I disconnected the ignition harness and moved it all the way to the other side of the engine bay, as well as the positive jump start cable.

dgknight 07-11-2013 09:02 PM

Great write up - thanks!

If you were going to do the oil separator again would you go the route of pulling the intake manifold, or fighting the various hoses with the manifold in place?

This will be one of my winter projects and I've watched videos of doing it with the manifold in place - looks like a royal PITA, but requires much less taking stuff off - obviously.


jjrichar 07-12-2013 03:23 AM

I would still personally go down the path of taking the manifold off. I personally think the chances of not fitting something correctly or breaking components are minimised by doing it this way. The downside is it will take you longer. Also, you have the chance to have a good look under here and check for other issues. I found stuff that I wouldn't have otherwise. Some people are concerned about pulling stuff apart and then having issues when it all goes back together again. I've never had problems with this, and I like that I have the chance to inspect components to fix problems early, rather than have a larger problem later.

dgknight 07-12-2013 11:57 AM


I will study your DIY again more carefully before I take this on.


intubater 05-25-2014 09:37 PM

3 Attachment(s)
Just removed my intake manifold on a 2000 323i. It took a total of 8 hours, but that was due to problems I encountered removing hoses. Especially the hoses at the firewall because of the small space. I pulled it off to replace the two coolant pipes that sit just under the intake manifold. Now that it's off, I am able to replace several small hoses that were falling apart and brittle. Here are some pics of the two pipes and how badly brittle they were. Attachment 559699Attachment 559700Attachment 559701

Now I just have to buy the pipes and put this thing back together without having extra parts.

A word to the wise, take a ton of pictures every step of the way so you don't forget anything when reinstalling.

The only problem I really encountered was when I thought all the bolts and hoses and wires were unplugged. The two fuel lined by the firewall are hell to remove (only by feel). Once off there is so much room to replace all the hoses and potential issues underneath.. It's not an impossible job (I'm not a mechanic, I'm a nurse) and I was able to do it. But I will say it is tedious and definitely requires patience. Good luck and let me know if anyone has questions as I wish I had help when I needed it.

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intubater 05-25-2014 09:42 PM


This was a good how to from pelicanparts.com those guys are awesome. There were a couple of steps missing. It didn't show how to remove the part where the air intake meets the intake manifold. You have to remove this to remove the bottom bolt that is holding the manifold in.

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