W/S212 bulkhead removal

[Conor]

Hi guys,

I've been puzzled for quite some time on how to access the bolts to replace the crankcase ventilation valve (PCV) on my E350.

Finally I checked WIS and it says that for my particular variant engine 272.983, "Remove bulkhead between wheels wells" is required, but there is no associated document.

Has anybody done this before?

You will see from the pics how tight it is.. The bottom bolt is the problem and also I have tried the offset spanner to no avail.

There are many videos online of people changing this but lucky for them they have a bit more room on their application :'(

 

[Wighty]

What about a 1/4 drive with a torx socket
Is there better access for the lower bolt from below

 

[Oldspanners]

https://forums.mercedesclub.org.uk/index.php?attachments/wp_20190525_009-jpg.50345/
On the my W203 with the M171 engine the brake vacuum booster is right up against the bulkhead as well perhaps not just as tight but hard to say, I used a 1/4" swivel head ratchet and a 8mm socket rather than the torx see the link above. On some jobs I've ground down a socket to the minimum depth as well. Hope this may be of some help.

 

[joderest]

is it accessed via the wheel arch by removing the liner ?

 

[Uncle Benz]

The bulkhead they refer to is the tinware curved plate at the back of the engine. It’s held with a selection of small screws, and the heater hose usually passes through it. It’s a kind of false bulkhead at the back of the engine bay with the wiper motor behind it, and the main firewall between the passenger compartment

 

[Conor]

Thanks for the input guys.

Unfortunately it won't be possible via the underside.

@Uncle Benz is spot on alright.. thanks! From what I can see there are two screws (one either side towards the top) holding it in place, along with a 13mm hex bolt on the offside front.

After removing those 3 fixings + the brake vacuum line the only thing is the coolant pipe for heat. I have removed the pipe on the engine side of the bulkhead. Had to buy a clamp pliers.. The problem now is the pipe on the other side of the bulkhead.. seems a bit tight.

Oh and I'm pretty sure I won't be able to fully remove it unplugging the wiring from the ECU and another controller.

I'll see if I can get that fitting off tomorrow and take a few pics.

Side note, I noticed the housing for the ECU connector was broken today and the various constituent wires expose.. along with there being bits of oil in and around there Some of the loom tape is also unravelling due to oil. I'm wondering about taking some kind of action on this as opposed to just ignoring it

I've been warned about oil creep in loom before, when I infamously took the car for a Post shock Purchase Inspection at MB Guildford. I have been thinking about stripping back the loom tape/covering and trying to purge the oil residue and get it back into a presentable manner. Any tips/warnings?

 

[Jim2]

Did the offset spanner work for the upper bolts? As Uncle Benz said, the firewall is flexible thin metal sheet, and can be bent a bit to make it easier to work sockets and spanners. Very strange that the offset spanner didn't work though... that would have been my "go to" tool for that particular job.. how about from underneath, using a combination of extension's and flexible "knuckle"?

Oops, our posts crossed ..only just now seen your last post Conor....So forget my suggestion.

 

[Conor]

Did the offset spanner work for the upper bolts? As Uncle Benz said, the firewall is flexible thin metal sheet, and can be bent a bit to make it easier to work sockets and spanners. Very strange that the offset spanner didn't work though... that would have been my "go to" tool for that particular job.. how about from underneath, using a combination of extension's and flexible "knuckle"?

Oops, our posts crossed ..only just now seen your last post Conor....So forget my suggestion.

Thanks Jim.

Unfortunately the offset tool didn't work, for the bottom one. Others not an issue.

If you look at the actual PCV part, you will see that the bottom one is right beneath the pipe connector meaning there is a nice bit of an inset to get to.. if the pipe connector wasn't there it would be fine I am sure.

Perhaps the picture doesn't do justice but it is very tight there. I imagine that if there was any reasonable way to access without removing the bulkhead MB wouldn't have included that step in their WIS document. They didn't even include a document on how to remove the bulkhead so it's a pure after thought. Worth noting that it's only applicable for my variant engine (E350 CGI with 292 BHP Code: 272.983) The regular 350, non CGI with 272 BHP isn't affected as it's a different setup.

I know nobody asked about the finer detail but perhaps a future me might appreciate it as information on this configuration is spare online.. ask me how I know.. (I google search and only get back my posts )

 

[Oldspanners]

Thanks for the input guys.

Unfortunately it won't be possible via the underside.

@Uncle Benz is spot on alright.. thanks! From what I can see there are two screws (one either side towards the top) holding it in place, along with a 13mm hex bolt on the offside front.

After removing those 3 fixings + the brake vacuum line the only thing is the coolant pipe for heat. I have removed the pipe on the engine side of the bulkhead. Had to buy a clamp pliers.. The problem now is the pipe on the other side of the bulkhead.. seems a bit tight.

Oh and I'm pretty sure I won't be able to fully remove it unplugging the wiring from the ECU and another controller.

I'll see if I can get that fitting off tomorrow and take a few pics.

Side note, I noticed the housing for the ECU connector was broken today and the various constituent wires expose.. along with there being bits of oil in and around there Some of the loom tape is also unravelling due to oil. I'm wondering about taking some kind of action on this as opposed to just ignoring it

I've been warned about oil creep in loom before, when I infamously took the car for a Post shock Purchase Inspection at MB Guildford. I have been thinking about stripping back the loom tape/covering and trying to purge the oil residue and get it back into a presentable manner. Any tips/warnings?

If it's oil wicking up the wiring as on the M271 it's in the copper strands of the wire and not between the loom tape and the wires. You need to find where the oil is entering and block it. I cleaned the connectors with electrical contact spray and compressed air several times until clear after fitting the blockers.
I've no experience of where the oil gets into the loom on your engine but unsurprisingly it will find its way to the lowest point first.

 

[Conor]

If it's oil wicking up the wiring as on the M271 it's in the copper strands of the wire and not between the loom tape and the wires. You need to find where the oil is entering and block it. I cleaned the connectors with electrical contact spray and compressed air several times until clear after fitting the blockers.
I've no experience of where the oil gets into the loom on your engine but unsurprisingly it will find its way to the lowest point first.

Ok thanks. Well.. historically the engine has had a fairly significant leak and i'm still trying to clean it down in places.

How does it get into the copper/inside the insulation. I would assume the connector would have to be exposed to the oil. I've not focused on this yet but i'll have to investigate.

I remember reading about some engines that had the problem you describe and there were blockers. I'm not sure mine is affected but will check.

Interested in opinions on whether I should leave "well enough" along or if I should act now as only bad can come from this in future.

Thanks.

 

[Oldspanners]

Ok thanks. Well.. historically the engine has had a fairly significant leak and i'm still trying to clean it down in places.

How does it get into the copper/inside the insulation. I would assume the connector would have to be exposed to the oil. I've not focused on this yet but i'll have to investigate.

I remember reading about some engines that had the problem you describe and there were blockers. I'm not sure mine is affected but will check.

Interested in opinions on whether I should leave "well enough" along or if I should act now as only bad can come from this in future.

Thanks.

On the M271 the oil gets in through the "cam magnets" that adjust the cam timing and wicks through the harness to notably the ECU and down to the 02 sensors. If yours is just an external spill it would certainly be better to do it earlier to prevent oil getting into connectors, it doesn't take much to start throwing up all sorts of codes.
I had a cam position sensor fault because of oil in the connector, a first I thought it was a continuation of the oil in the harness, it was just about noticeable and I cleaned it three times. The actual fault was the oil was coming through the sensor itself as the internal seal broke down, replacing it cured it.
I would take time and do a good clean up, as they say the dark nights are coming

 

[Jim2]

Thanks Jim.

Unfortunately the offset tool didn't work, for the bottom one. Others not an issue.

If you look at the actual PCV part, you will see that the bottom one is right beneath the pipe connector meaning there is a nice bit of an inset to get to.. if the pipe connector wasn't there it would be fine I am sure.

Perhaps the picture doesn't do justice but it is very tight there. I imagine that if there was any reasonable way to access without removing the bulkhead MB wouldn't have included that step in their WIS document. They didn't even include a document on how to remove the bulkhead so it's a pure after thought. Worth noting that it's only applicable for my variant engine (E350 CGI with 292 BHP Code: 272.983) The regular 350, non CGI with 272 BHP isn't affected as it's a different setup.

I know nobody asked about the finer detail but perhaps a future me might appreciate it as information on this configuration is spare online.. ask me how I know.. (I google search and only get back my posts )

Yes Conor, I saw that.....awkward does not even begin to describe it..One problem is that these engines / transmission's/ axles etc...are all fully assembled before being installed on the production line...so what was the simplest of jobs at that stage, becomes a nightmare after assembly. Its a very good idea to document it, for future reference....I don't think that you will be the last one to experience this problem. BTW, You mention WIS..how do you access it? I downloaded the whole program ( about 20 GB) but can't figure out how to Assemble it into a working program....way beyond my IT capabilities

 

[Conor]

On the M271 the oil gets in through the "cam magnets" that adjust the cam timing and wicks through the harness to notably the ECU and down to the 02 sensors. If yours is just an external spill it would certainly be better to do it earlier to prevent oil getting into connectors, it doesn't take much to start throwing up all sorts of codes.
I had a cam position sensor fault because of oil in the connector, a first I thought it was a continuation of the oil in the harness, it was just about noticeable and I cleaned it three times. The actual fault was the oil was coming through the sensor itself as the internal seal broke down, replacing it cured it.
I would take time and do a good clean up, as they say the dark nights are coming

The dark evenings sure are coming.. and the days getting cold too. Pity I didn't get around to this in summer. I was pre-occupied.

I have been doing some reading and it would appear the M272 isn't affected in the same way as the M271. I still do have an issue though.. the oil is from a previous leak I am guessing.

I bought some contact cleaner today and will be using that. Shall I use that on the wires or just the block? What to use on the wires.

Yes Conor, I saw that.....awkward does not even begin to describe it..One problem is that these engines / transmission's/ axles etc...are all fully assembled before being installed on the production line...so what was the simplest of jobs at that stage, becomes a nightmare after assembly. Its a very good idea to document it, for future reference....I don't think that you will be the last one to experience this problem. BTW, You mention WIS..how do you access it? I downloaded the whole program ( about 20 GB) but can't figure out how to Assemble it into a working program....way beyond my IT capabilities

Yes, a big pain. So.. the final piece of the puzzle is where the coolant hose passes through the partition by means of a 3 way connector. I have removed the engine side (tough enough). But the cabin side is very challenging.. I can't get the clip pliers into the space to catch it. I wonder can I spray some silicone spray on the clip and then try and rotate it with flat screwdriver or something?

Hopefully you will see what I mean.

Some pics of damaged connectors/oily wiring too.

Also, you will see in the final photo that the sound proofing in the bulkhead has started to disintegrate and breaks away easily if touched. Annoying and risky as stuff could fall into the MAF. Any suggestions on how I could tidy that up when I finally get it out? I am thinking about some kind of compound that I can apply to just seal up the foam and prevent further debris. Would also need to be relatively tolerate to heat. Thanks.

 

[Oldspanners]

The dark evenings sure are coming.. and the days getting cold too. Pity I didn't get around to this in summer. I was pre-occupied.

I have been doing some reading and it would appear the M272 isn't affected in the same way as the M271. I still do have an issue though.. the oil is from a previous leak I am guessing.

I bought some contact cleaner today and will be using that. Shall I use that on the wires or just the block? What to use on the wires.



Yes, a big pain. So.. the final piece of the puzzle is where the coolant hose passes through the partition by means of a 3 way connector. I have removed the engine side (tough enough). But the cabin side is very challenging.. I can't get the clip pliers into the space to catch it. I wonder can I spray some silicone spray on the clip and then try and rotate it with flat screwdriver or something?

Hopefully you will see what I mean.

Some pics of damaged connectors/oily wiring too.

Also, you will see in the final photo that the sound proofing in the bulkhead has started to disintegrate and breaks away easily if touched. Annoying and risky as stuff could fall into the MAF. Any suggestions on how I could tidy that up when I finally get it out? I am thinking about some kind of compound that I can apply to just seal up the foam and prevent further debris. Would also need to be relatively tolerate to heat. Thanks.

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Release the plug and check it and the socket for any oil intrusion, give it a good squirt of cleaner if it's oily and a blast of compressed air towards the outside of the plug if there is. Otherwise it's just dirty on the outside wipe it and put the cover back on.

 

[Conor]

Release the plug and check it and the socket for any oil intrusion, give it a good squirt of cleaner if it's oily and a blast of compressed air towards the outside of the plug if there is. Otherwise it's just dirty on the outside wipe it and put the cover back on.

Will do thanks.. I have no air and the plug connector is actually broken off and won't go back on. It seems as thought the air box damaged but unsure as to how.

 

[Uncle Benz]

You don’t need to remove the hoses from the plastic connector. It unclips from the bulkhead panel and can stay there with the back side hoses still on. The engine bay side, lift the wire spring clip and seperate the plastic sections

 

[Conor]

You don’t need to remove the hoses from the plastic connector. It unclips from the bulkhead panel and can stay there with the back side hoses still on. The engine bay side, lift the wire spring clip and seperate the plastic sections

Oh ok, interesting, thanks. I felt like that was an avenue to explore alright.. it's just that the plastic springy type notches on the panel are quite tight.. i'll probably end up braking them.

When you talk about wire spring clip, what do you mean? The clip around the coolant hose on the engine side, or something else?

What plastic sections are you referring to? Does the piece that sits in the bulkhead come apart as two pieces?

Okay.... just had a quick google.. Is this what you mean? This kind of thing? Oops, I already removed that pipe by removing the hose with a coolant clip pliers which I bought. Damn lol.

P.S. That photo below makes it look so easy, so much room there but not for me.

 

[Uncle Benz]

I think you’ve answered your own question there!

you won’t break the two little clips that hold it into the bulkhead if you are careful. You don’t need to lean on them much to pop the unit out

 

[Conor]

Right guys...

Today was a challenging one and this job nearly has me beat but I am so close i'm not going to give up.

I managed to unclip (And lose) the wire clip from the coolant connector and got things apart, might (I did!) have lost a tab also.. but hey ho.. these plastics are pretty brittle in later life so I don't get too het up about it.

I will admit that it was brute force and ignorance that got the bulkhead out.. and in hindsight (zoom in) you will see at the bottom that there may have been a couple screws retaining things on the under side but I will check that in morning. It was difficult to get a good grip and leverage on the piece so I ended up standing up on the engine bay and pulling it out by grabbing the centre with a pliers!

You can also get a better view of the broken down sound proofing also.. I think i'm going to find some kind of compound / sealant to tidy that up a bit.

At this point I thought I was away scot-free and could access the screw on PCV. It turns out there are 4 bolts, and the fourth is impossible, I can hardly touch it. It's the one that is the closest to the passenger side under and very close to what looks the PTO for the compressor for the high pressure injection, which is unique to this engine 272.983

I think the get at the final bolt, I need to remove the heat shielding which in theory isn't a problem. I removed the screws from accessing at top + bottom. But from viewing below it looks like the heat shielding goes around this big strut like thing that is pointing from the firewall towards the front. Like it's a support component.. and I really don't know about removing that. But that said.. if I don't, I can't remove the shielding.

I'm bummed out at this point and couldn't take pics from under as it was too dirty and I forgot to bring my phone.

At this stage it's worth pointing out that I don't feel too good about hammering the heat shielding for more space as it will probably make re-installing the "bulkhead" a lot more difficult that it will already be.

Any ideas? I couldn't have gotten this far without your help and I am very grateful!



Here I could use both my sockets and offset spanner to access 4 of the 5 bolts. The 5th is still a problem and requires that heat shielding to come off.

 

[Conor]

..Ok. So I have identified the part I can't remove, the heat shielding for the exhaust.

It's part number A2126800822 and looks like this. See the hole in the middle. There is a fairly significant strut or something going through it that I really don't know about removing. What is it? Can I remove it?

I'm just going to leave this here: I don't generally worry about putting stuff back together but I fear this will be less fun that getting them all out.

.. On the up side. Since purchase the car has received new air springs rear, new discs + pads, alternator and hopefully soon it will have oil consumption issue fixed. I'm sure there are plenty more things to go but it should be in good stead for a while, touch wood. (Don't worry, i'm not superstitious )

Ok... found it. It's the "Steering coupling" part, Anything I need to know about removing this.

Why stop now.. right? I've already torn the car apart...