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Pelican Technical Article:

Intake Manifold Removal

Time:

3 hours3 hrs

Tab:

$150

Talent:

****

Tools:

All of them

Applicable Models:

Mercedes-Benz W210 (1996-03)

Parts Required:

Manifold gasket

Hot Tip:

Get a set of bolt extractors.

Performance Gain:

Repaired vacuum leaks equal better performance

Complementary Modification:

Replace fuel pressure regulator

In this article, I will go over the steps involved with removing and/or replacing the intake manifold on your W210 Mercedes with a M104 engine. Removing the manifold is challenging but can be accomplished by the do-it-yourselfer with a few pointers we've learned by doing this job.

The most important step in this job is to disconnect the battery. We are working around GASOLINE. It is flammable. It is very easy to ignite gasoline with only a small short circuit. Be safe and remove the 11mm bolt holding the battery terminals disconnect together in front of the rear right seat.

Begin by removing the MAF sensor assembly and also the intake plenum running across the top the engine. This is held on by three 10mm nuts on top of the valve cover. Release the clips on the MAF sensor to remove it from the airbox. You'll also need to loosen the hose clamp holding the upper intake plenum to the throttle body. The clamp itself is located in a tight space. A 7mm universal joint socket makes this job much easier. Once the hose clamp is loose, pull the whole intake plenum assembly up and off the valve cover.

Once removed, we will need to relieve the pressure in the fuel system. It's best to wait a day or two without running the engine before you do this job. This is for two reasons: You want to have the engine cold and also to help bleed off some of the pressure in the fuel system. To completely bleed off the pressure, you'll need to remove the metal cap over the Schrader valve in the center of the fuel rail and cover it with a disposable shop rag. Use a screwdriver to press the Schrader valve in. The rag will soak up most of the fuel that will spray out of the valve. Use caution when doing this as you will be working around raw gasoline.

You may be able to bleed off the pressure in another manner by waiting until the car is very low on gasoline and simply run the engine until it runs out of gas. Additionally, you may be able to remove the fuel pump relay achieving the same effect the pump will not deliver fuel to the engine, although this may trigger a check engine light. Its easier to just press the Schrader valve in and be ready to soak up any raw fuel that may come out. Be sure to have a fire extinguisher nearby just in case and wear goggles. Be sure to dispose of a gasoline soaked rag in a metal container and work in a well-ventilated area.

The next step is to disconnect the fuel feed and return lines near the center of the line. Use a 17mm wrench and break loose the two connectors on the rubber fuel lines while counter holding the nuts on the metal fuel rail. It's a good idea to have a rag underneath the fuel line connections to catch any fuel that spills out. Don't forget to also remove the vacuum hose going to the fuel pressure regulator. Also, squeeze the tabs on the electrical connectors going to each fuel injector.

Now we will need to remove the fuel rail from the engine. This is where the job gets somewhat difficult as the fuel rail is held on by five of the 6mm Allen head bolts that also hold the intake manifold to the engine. I've found that it is very difficult to reach these bolts head on with an Allen wrench or even a hex bit socket. It should also be noted that in our case, three of the bolts were stripped out internally. This necessitated the use of what is called a bolt extractor. This is a nifty little tool that grips the outside of the bolt head and applies more force the more you turn it counter-clockwise. I'd also recommend you change the bolts to a conventional hex head to make re-assembly easier. I found it much easier to use the bolt extractor on ALL of the bolts holding the manifold to the head.

Cut the zip ties holding the wiring loom to the fuel rail, pull the loom free and pull the fuel rail up and out of the intake manifold. Don't forget to also remove the 5mm Allen screw holding the dipstick tube to the intake manifold. This will make removing the rail a bit easier. Once the rail is removed, you'll have better access to the remaining mm bolts holding the intake manifold to the cylinder head. Also loosen the hose clamp holding the intake boot to the throttle body.

You'll now need to remove the hose clamps around the boots holding the intake manifold tubes to the lower metal plenum piece. This is one of those jobs that is easier said then done as access is not that great. Depending on which way the hose clamps are oriented, you may be able to access the front boot from inside the engine compartment. I found that the easiest way to reach the rear boot is from under the car.

From underneath the car, you will also see some of the vacuum hoses connected to the underside of the manifold. Pull these off and check the condition of the rubber connection pieces. These little elbows are cheap, so it's a good idea to replace them as needed. Additionally, there are two larger vacuum lines connecting to the underside of the manifold. Remove the crimp fittings on each and pull these hoses off. You'll probably need to replace these altogether, so don't feel bad about breaking them.

Once everything is loose, pull up on the manifold to release it from the lower intake manifold and also the cylinder head. Take your time and stop if you come across any harnesses or anything else still attached or plugged in. The key here is to take your time and make sure you don't damage anything while removing the manifold.

Begin by removing the upper air intake tube that runs along the top of the valve cover.
Figure 1

Begin by removing the upper air intake tube that runs along the top of the valve cover. See our article on replacing spark plugs for more info. Once removed, pull the black plastic cover off the valve cover (green arrow).

Remove the cap covering the fuel pressure test port (green arrow).
Figure 2

Remove the cap covering the fuel pressure test port (green arrow).

Place a rag next to the Schrader valve inside (green arrow) and use a small screwdriver to press the valve down.
Figure 3

Place a rag next to the Schrader valve inside (green arrow) and use a small screwdriver to press the valve down. This will bleed off any residual pressure in the line.

Disconnect the two 17mm fittings hold the feed and return lines to the fuel rail (green arrows).
Figure 4

Disconnect the two 17mm fittings hold the feed and return lines to the fuel rail (green arrows). It's a good idea to have a rag underneath as some fuel will probably spill out. You'll also need to counter hold the nuts built into the rail using another wrench (yellow arrows).

Remove the small 5mm Allen screw holding the dipstick tube to the intake manifold (green arrow) and also disconnect the vacuum line going to the fuel pressure regulator (purple arrow).
Figure 5

Remove the small 5mm Allen screw holding the dipstick tube to the intake manifold (green arrow) and also disconnect the vacuum line going to the fuel pressure regulator (purple arrow). It also helps to pull the dipstick out and set it aside for the time being.

Now disconnect the electrical connectors to each fuel injector by squeezing the two tabs together (green arrows) and pulling the connector off.
Figure 6

Now disconnect the electrical connectors to each fuel injector by squeezing the two tabs together (green arrows) and pulling the connector off.

It's very difficult to show the locations of the 6mm bolts that hold the fuel rail to the intake manifold, So I've included thisPicture to demonstrate with the fuel rail removed (green arrows).
Figure 7

It's very difficult to show the locations of the 6mm bolts that hold the fuel rail to the intake manifold, So I've included this picture to demonstrate with the fuel rail removed (green arrows). Take your time as these bolts can be very difficult to remove.

Now cut the zip ties holding the wiring loom to the fuel rail, pull the loom free and pull the fuel rail up and out of the intake manifold.
Figure 8

Now cut the zip ties holding the wiring loom to the fuel rail, pull the loom free and pull the fuel rail up and out of the intake manifold.

Now remove the remaining four 6mm bolts holding the intake manifold to the cylinder head (green arrows).
Figure 9

Now remove the remaining four 6mm bolts holding the intake manifold to the cylinder head (green arrows).

Here you can see the two hose clamps (green arrows) on the front intake boot that connects the upper and lower parts of the intake manifold.
Figure 10

Here you can see the two hose clamps (green arrows) on the front intake boot that connects the upper and lower parts of the intake manifold. Unscrew the 17mm nut on the vacuum connection on the lower metal manifold to the brake booster to gain a bit more room (purple arrow).

This picture shows the hose clamps on the rear boot looking up from under the car.
Figure 11

This picture shows the hose clamps on the rear boot looking up from under the car. This is about the only way you'll be able to reach these clamps. Once these hoses are loose, you can pull up on the intake manifold enough to disconnect a couple more harnesses that run through the runners.

Once the intake has been elevated, you can disconnect the wiring harness going to the throttle body and feed it back through the runners on the intake manifold.
Figure 12

Once the intake has been elevated, you can disconnect the wiring harness going to the throttle body and feed it back through the runners on the intake manifold. Lift up the locking tab (green arrow) on the harness and pull the connector out of the throttle body.

You'll also need to feed the wires back for the throttle body electrical connector, two knock sensor connections, the connection for the air resonance flap and also the oil level sender.
Figure 13

You'll also need to feed the wires back for the throttle body electrical connector, two knock sensor connections, the connection for the air resonance flap and also the oil level sender. Shown here is the rear branch of wires (green arrow) There will be one at the front as well.

Shown here is the front knock sensor (green arrow) with the harness already removed.
Figure 14

Shown here is the front knock sensor (green arrow) with the harness already removed. NOTE: manifold and electrical connector have already been removed for clarity (it's very difficult to photograph this with the manifold in place).

Remove the electrical connector going to the rear knock sensor (green arrow) and feed it up from between the intake runners.
Figure 15

Remove the electrical connector going to the rear knock sensor (green arrow) and feed it up from between the intake runners. NOTE: Harness has already been removed.

Now remove the electrical connector going to the oil level sender (green arrow) on the oil pan and feed it up from between the manifold runners.
Figure 16

Now remove the electrical connector going to the oil level sender (green arrow) on the oil pan and feed it up from between the manifold runners.

In this picture, you can see the two hoses that attach to the underside of the intake manifold.
Figure 17

In this picture, you can see the two hoses that attach to the underside of the intake manifold. In our case, I simply could not get any tool in there with the manifold attached to remove the clamps (green arrows). Instead, the hoses snapped the second I put a small bit of upward force on them. You'll want to remove the clamps and what's left of the hoses. You can see the hose clamp that holds the intake boot to the throttle body (yellow arrow). Also remove all of the old intake manifold gaskets (purple arrow) from the manifold.

Shown here is the engine with the intake manifold removed.
Figure 18

Shown here is the engine with the intake manifold removed. You'll note some of the vacuum hose connections that should be inspected for cracks. It's a good idea to replace ALL the rubber connectors while you're in there. Shown here are the new intake boots (part number 104-141-17-83) fitted to the lower metal portion of the intake manifold (green arrows). Also shown here are the various vacuum hose connections on the lower manifold; the two larger hoses to the underside of the intake manifold (purple arrows) as well as the smaller hose connections that should be replaced (yellow arrows). Don't forget to also re-connect the vacuum line to the brake booster (blue arrow). NOTE: The throttle body has been removed from the manifold in this car for clarity.

Attach the new vacuum hoses to the bottom of the intake manifold (part numbers 104-094-36-82 and 104-094-35-82) (green arrows) with new hose clamps and place the new intake manifold gaskets (part number 104-141-10-80) in the grooves at the end of each intake runner (purple arrow).
Figure 19

Attach the new vacuum hoses to the bottom of the intake manifold (part numbers 104-094-36-82 and 104-094-35-82) (green arrows) with new hose clamps and place the new intake manifold gaskets (part number 104-141-10-80) in the grooves at the end of each intake runner (purple arrow).

Now place the new vacuum connectors in place on the lower manifold (green arrows) along with the vacuum connection to the throttle body (purple arrow).
Figure 20

Now place the new vacuum connectors in place on the lower manifold (green arrows) along with the vacuum connection to the throttle body (purple arrow).

Clean the mating surfaces on the cylinder head and also make sure that the two locating dowels (green arrows) are in place on the cylinder head.
Figure 21

Clean the mating surfaces on the cylinder head and also make sure that the two locating dowels (green arrows) are in place on the cylinder head.

Place the intake manifold back in position next to the engine.
Figure 22

Place the intake manifold back in position next to the engine. Attach the lower ends of the hoses on the upper manifold to the connections on the engine (green arrow) and run the wiring harness through the runners on the intake manifold. Re-connect the harness to the throttle body. Reconnect the harnesses going to both knock sensors (front sensor shown purple arrow) and also the oil level sender. Seat the manifold into the boots on the ends of the lower metal manifold and secure the hose clamps.

Seat the throttle body intake boot back onto the top of the throttle body and tighten the 7mm hose clamp (green arrow).
Figure 23

Seat the throttle body intake boot back onto the top of the throttle body and tighten the 7mm hose clamp (green arrow).

It's advisable to replace the seals that hold the fuel injectors to both the fuel rail and also the intake manifold (green arrows).
Figure 24

It's advisable to replace the seals that hold the fuel injectors to both the fuel rail and also the intake manifold (green arrows). Please see our article on fuel injector replacement for more info.

I chose to replace the internal hex head bolts used on the M104 engine with conventional hex head bolts (green arrows), should I ever need to remove it again.
Figure 25

I chose to replace the internal hex head bolts used on the M104 engine with conventional hex head bolts (green arrows), should I ever need to remove it again. This will make it much easier. The bolt size you'll need is M8 x 50.

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Comments and Suggestions:
hussain Comments: this attachment is connected to throttle body boot. what is its function.
September 10, 2016
  Followup from the Pelican Staff: Can you share a photo? Possible you are referring to the variable intake control. - Nick at Pelican Parts  
hussain Comments: what is the attachment to the underside of intake manifold in e320 96 or 97 model of mercedes m104 engines
September 10, 2016
  Followup from the Pelican Staff: Can you share a photo? Possible you are referring to the variable intake control. - Nick at Pelican Parts  
ecw121 Comments: 2000 MB E430, getting a low coolant indicator, can't find anywhere there is a leak, replaced overflow cap, have refilled 3 times, took to shop and was told that 3 different issues, pressure test system and head gasket leak test, was told fan clutch need replacedantifreeze evaporating 2nd shopradiator leaking internally and going back thru trans lines is why we are not seeing leak spot finally changed oil and WOW, oil looks like milky milkshake and after all previous finds where repaired to include radiator flush new belts and hoses, new thermostat, and oil change is when we find this, previous head gasket test indicated no headgasket leak, would this be the intake manifold or something else.....
August 31, 2016
  Followup from the Pelican Staff: Could be an a heat exchanger or the head gasket. Not much else can do it. - Nick at Pelican Parts  
Lisa Comments: on a clk500 intake, there is a vacuum hose coming from the bottom front of the manifold. That has broken off. It is part of the secondary air system. There seems to be now easy way to put a new hose on as the work area is very limited. Does that hose run thru the manifold or is there an "end" to attach a new hose. That hose runs up to what looks like a check valve on the drivers side of the engine. 2005 CLK500 w209. I have heard that I may have to replace my intake manifold to fix this hose. Really?
March 26, 2016
  Followup from the Pelican Staff: Use a small piece of vacuum hose and a vacuum butt connector to join them. Then you don't have to remove the intake.

Give our parts specialists a call at 1-888-280-7799. They can figure out what part or repair kit you need.
- Nick at Pelican Parts
 
Merctech36 Comments: Hi I have a 1996 C280, it idles rough and jumps some time, I have done the wiring, replaced maf and coils +wires. I have done the intake manifold seals and injectors, my mechanic didn't put the 2 dowels back, will this cause my idle problems
November 26, 2015
  Followup from the Pelican Staff: Is the check engine light on? Sounds like an engine misfire. I would check spark, fuel and compression on all cylinders.
- Nick at Pelican Parts
 
Paul Comments: Nick, so I'm about to do this project and I'm ordering 104-17-83; 104-094-36-82; and 104-094-35-82. Could you also help me with part numbers and required quantities for all the other vacuum connectors? I'm trying to get it done once. Thanks a million
September 15, 2015
  Followup from the Pelican Staff:
I’m not the best with part numbers.

Give our parts specialists a call at 1-888-280-7799. They can figure out what part or repair kit you need.
- Nick at Pelican Parts
 
techhh Comments: great info, but we have a tech that wants to op\n the c320, and as the dealer said not too, the issue is that they cnnot get the code to reset, and since they already messed with it, and made a large ding on the motor side I feel the issue is not in the intake, but in the hed where the ing is there due to removing the intake wrong
April 20, 2015
  Followup from the Pelican Staff: What code? What are you trying to fix? - Nick at Pelican Parts  
RE Comments: This some very helpful info a DIY. Your color coded arrows was great idea, thanks. My cousin and I have twice due to oil leaks, replaced the upper timing chain cover gasket & the value cover gasket.However, I don't think that we slightly oiled the upper face and coat the cover gasket with a sealing compound to resist oil leakage. Is this the proper procedure. Thanks
April 2, 2015
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts
 
oldtrucker Comments: act1292 is asking for torque specs.
Since this is a 104 and I was working on a similar project, I found the bolts should be torqued at 25Nm which converts into approx. 18 ft/lbs.
October 12, 2014
  Followup from the Pelican Staff: Thanks for the input on this one. We appreciate the help.
- Nick at Pelican Parts
 
Hans Comments: Please tell me where the IAT sensor is located on 1997 C 280, cant find it in 2 hours....thanks
September 17, 2014
  Followup from the Pelican Staff: If I remember correctly, It is located towards the fire wall on the air tube just before the throttle body. - Nick at Pelican Parts  
ebontrager93 Comments: I bought a 1994 C280 at an auction and I can't get it to start. There's a small hose going into the intake manifold and the hose is broken. I'm not exactly sure what the hose does and the hose appears to be permanently attached to the intake manifold. I feel like that broken hose is why the engine won't start. Could you confirm or deny? Also it appears as though I would have to replace the intake manifold in order to fix the problem. again, can you confirm or deny?
thanks
August 30, 2014
  Followup from the Pelican Staff: I can't help without knowing what is missing from the system when you are trying to start it. When your engine doesn’t start you’ll want to check the basics. Check spark, fuel injector pulse and pressure fuel, volume and quality. Are there any fault codes? Once you figure out what is missing, it will be easier to diagnose.
- Nick at Pelican Parts
 
act1292 Comments: Very nice write-up. I used this to guide me on fixing a clogged EGR tube. Really the only thing missing are torque specs for the intake manifold/fuel rail bolts.
May 13, 2014
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts
 
Deric31 Comments: When you mentioned a faulty crankcase ventilation system the charcoal canister is all that pulls up, what exactly would I need to replace to fix the crankcase ventilation system?

Thank you
February 19, 2014
  Followup from the Pelican Staff: There are hoses that run to the throttle housing intake duct that fail, they are part of the crankcase vent system. I would start by checking there. Give our parts specialists a call at 1-888-280-7799. They can help put together a parts list. - Nick at Pelican Parts  
Deric31 Comments: Or the regeneration purge valve, there are so many different names for it that I've seen, I'll try to upload a pic. I was wondering if this is what you are talking about, when you mentioned the crankcase ventilation system.
February 14, 2014
  Followup from the Pelican Staff: That looks like a charcoal canister purge valve. - Nick at Pelican Parts  
Deric31 Comments: The crank case vent valve I believe it's called, they are all marked with MOT on the top.
February 13, 2014
  Followup from the Pelican Staff: Ok got it. I replied to you in the thread of your other request. - Nick at Pelican Parts  
Deric31 Comments: Thanks for your help, I'm going to check that and if it needs replaced I will call and order from you guys if you have it in stock. Also I did check the crank case ventilation if that's the part that says MOT on it. I cleaned it out with MAF cleaner and it started ticking and pumping but I dont notice it doing that all the time so I don't know if that's normal, I don't get a check engine code for it either.
February 11, 2014
  Followup from the Pelican Staff: I am not sure what you mean by MOT. - Nick at Pelican Parts  
Deric31 Comments: I'm getting 2 codes P0410 and the other is for the 02 sensor, and I noticed oil out of the boots. The first code is for the secondary air injection pump which seems to kick on normal. Could that be the cause of my code and is the crankcase breather system normally a valve that needs replacing ? I looked it up and it's showing a pcv valve but as far as I know the 97 mercedes e320 doesn't have a pcv valve.
February 8, 2014
  Followup from the Pelican Staff: The air pump may be turning on, but the air from the pump may not be making it into the exhaust. I would address that issue, inspect the secondary air check valve and vacuum hoses. There will be a crankcase ventilation system, it may be faulty if there is excessive oil in the intake air boots. - Nick at Pelican Parts  
Deric31 Comments: On figure 10, the intake boot mine is leaking oil from both boots where they clamp. Is that normal? I know it leaking isn't but as far as oil going through it? I'm trying to find out if I have to replace boots or something else. Any help would be appreciated.
February 6, 2014
  Followup from the Pelican Staff: You could have a faulty crankcase breather system. Allowing excess oil in the intake manifold. - Nick at Pelican Parts  

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