**UPDATE** Had to do the job again, but this time I replaced the $12 hose and 2 lower hoses and check valve. See link.

So after reading about the many many people suffering this nasty problem, I decided to do my bit for this wonderful forum.

Not sure exactly what this hose does (it connects a metal part to a plastic part), but word on the street has it that if it springs a leak/tear, then the CEL will turn on and throw a crapload of codes (which is a bad thing :p).

The problem is caused by factory clamps that are too tight, on top of the original hoses being made of a not-so-durable grade of rubber. Left unchecked, the clamps will cut through the hose at around 70-100k km and cause problems.

All vehicles with the M271 engine (2003-2005 C230k), especially the earlier runs, will have this problem. Mercedes-Benz has released 4 (yes, FOUR) versions of this rubber hose. On my 2003, I had the 1st (ie oldest) version.

MB wants some 7h labour(!) to change this hose. Save yourself a few bills and do this yourself!

Parts needed:
A271-018-12-82-64 Hose (anything lower than 12 for the 3rd number is old)
2 hose clamps (buy from dealer or auto parts store)

Tools:

Torx T15 bit
Torx T25 bit - the shorter the shaft, the better
E10 Inverted Torx bit, ratchet set, extension (at least 3")
Hacksaw if your E10 bit is 3/8" drive instead of 1/4" drive (I hate MB )
Pliers or hose clamp remover (I recommend the latter if you already have one, but don't go out to buy one just for this one piece)
Slot screwdriver (as narrow and long as possible, this is to disengage a hose clamp)
Whatever bit you need to secure your new hose clamps
A crapload of patience and self-restraint, to prevent oneself from exploding into murderous rage while attempting this fix
A 6-pack of beer (most important tool for this upgrade, gawd was it painful)
Ice or mini-fridge for the beer
A friend/relative with functional arms

 

Step 1: Open the hood. You can raise it to vertical if you want, though this is unnecessary.

Step 2: Remove intake hose. This one is pretty straightforward. Standing in front of the car (so you're facing the rear), push down (ie towards the ground) where the red lines are, then pull towards you. There's still a hook on the other side (ie the bottom), so after you disengage those 2 hooks and free them completely, you need to tilt the piece towards you, then lift up. I moved mine towards the front of the car, and left it there.

 

Step 3: Unbolt rear of airbox. This is where one learns to love MB.

You'll need your E10 inverted Torx bit.

One bit is nice and easy if your drive shaft is long enough. The other one is only doable if your bit is 1/4" drive. No idea what kind of genius decided to put a plastic tube (shown in purple) leading to that bolt. That thing stops anything bigger (like my 3/8" drive E10 bit) from reaching the bolt! I got pissed and took a hacksaw to the damn tube. 10 minutes later, half the tube was sliced off. Another 30s and the bolt was off.

The bolts do not pull out per se, so if they're loosened enough for you to lift up, then that's good enough.

 

good fix bro!

now i have to fix my hose again lol........

 

Step 4: Remove excess stuff

Undo the Torx screw (T-20 in red), and also the 2 MAF sensor screws (purple). Yes there are 3 MAF screws in total (the 3rd one is on the bottom side of the thing) but I didn't bother; having 2 loose gave me the flex I needed.

Unclip the ECU cable (2 in total, circled at bottom of pic) by pulling the handle-latch thingies and lifting the connectors upward. Also unclip the 2 other connectors (green arrows), and the vacuum hose (green circle, squeeze the opposite ends and lift upwards).

 

Step 5: Remove/dislodge airbox

One person needs to lift the "back" of the box (where the inverted Torx bolts were) while the other person pushes the airbox towards the rear of the car. There's a shaft-thing that fits into a rubber plug on the left and right sides of the airbox; you want to slide the shafts completely out of the rubber plugs. It's tight and you might think you'll break something, but the MAF has just enough "give" to let the airbox slide without breaking that 3rd screw you didn't remove (from Step 4).

Half the battle!

 

Step 6: Remove old crappy $12 hose

Lift the airbox (some people were able to remove the whole thing but I couldn't figure out how to do that for the life of me ) and look underneath. Behold our favourite hose. It's very obvious where the "near" end goes (red arrow) but the "far" end seems to disappear into oblivion. Stick your right hand and follow it to the end. (helps to have nice slim girly/Asian hands here )

The "closer" clip is a regular hose clamp that can be undone with a pair of pliers (hose clamp or regular variety). 1 down. The other is a Click-r type which has no tabs. Rotate it around until you see the ends (instead of 2 tabs, you'll see 1 bump). Take your narrow + long slot screwdriver and jam it into the middle of that thing and push downwards. Twisting the screwdriver shaft while doing it may help. Eventually it'll pop off. Pull that end of the hose upwards and it's free.

My old hose (2003 C230k) was part A 203-018-04-82. According to the Parts department, MB superceded this hose not once, not twice, but THRICE. See pic. Old hose + clamps is at the top. The newer hose is made of a different type of rubber, and is molded in 2 halves along the length.

Upon closer inspection, sure enough, my hose had a tear in it. Thanks to those of you who brought this problem to light in the W203 forum! See pic.

 

Step 7: Attach new hose

Wipe the parts of the engine where the hose goes if you so desire. I found the brass piece where the "farther" end goes (orange circle) was covered in motor oil/grease. Wiped it clean with a paper towel.

Stick the "far" end back onto the brass piece (on the new 12-18 hose, it's the end that's slightly thicker; push downwards until it goes all the way in), then slip one of the pipe connectors down and slide it into place. Because of the angle it's a real biotch to tighten. I used my long narrow slow screwdriver (held in right hand) to keep the clamp in place while I tightened it with my left hand. Patience, my friends, it's all downhill from here.

The "closer" end (yellow arrow) is much easier to reattach.

Step 8: Reassemble airbox

Reverse all steps and you're done!

Step 9: Enjoy beer Pull out that bottle opener and enjoy your 6-pack.

 

Great Work! Good to see some tech instead of .... Ohh, I'll just stop there.

E

 

Great job. Adding to the DIY sticky now. Thanks for doing this.

 

So what's the hose for?

 

...and how do you know if it needs to be replaced?

 

And for your reading pleasure, the PDF version of this DIY, linked here.

I am really bored at work

 

lol! Excellent DIY. Thanks for taking the time to put this together.

I’ll never get messed up by that hose, but you’ve saved your DIY bros some aggravation.

 

Many threads on that.
Throws misfire codes on all cylinders I believe.
Please search.

 

No, It does not. It sets a check engine light with a partial load code.

 

I will be doing mine this weekend. I will also clean my MAF

 

Hey Jim,

where in Garden you located? You drive a Coupe?

My business is in Gardena. If you need help, let me know.

E

 

Great DIY!
One question - do you have to get the hose from the dealer?

 

Thanks for the offer E., I'll probabbly be doing this at my Bnlaw's house In OC
he's garage is nicely setup to do any type of work.

J.

 

Unless you know someone at a MB parts warehouse, dealer is the only place. Just pay the $12 (okay, technically it was $13.57CAD + $5 for clamps) already

 

I just finished replacing my $13.69 hose, you guys won't believe what I found while removing the old hose. Well, it turns out that someone at the factory in Germany, forgot to put one of the clamps, mine had only one, the one attached to the engine block was missing. I went ahead and replaced the hose anyway, since I had everything taken apart, but the old hose was still in good shape no cracks.

My leaks were coming fron the missing hose clamp. not from a cracked hose.

 

SUE MB!

 

MB just sent out a recall on these hoses..

 

seriously?