Join Date: Sep 2009
My Ride: 330 Ci convertible
Project M54 Engine: 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.
Last edited by jjrichar; 02-08-2012 at 11:48 PM.