How to clean your MAF

[Parrot of Doom]

note: The original thread including all replies to this is located here > http://forums.mercedesclub.org.uk/showthread.php?t=18298

Feel free to point out any glaring mistakes I made while doing this

My engine has been playing up a bit, surging when cold in the morning, occasional misfire. Chief suspect (and cheapest to investigate) was the MAF, cleaning it would certainly do no harm. So heres what I did:

First, open the bonnet (duh!). The MAF can be found exiting the air filter box for the engine. On mine (300TD) its on the offside of the engine bay, at the front. You can see a small electrical plug attached to the air intake.

1) Remove the plug

2) Unclip the air filter box

3) Undo the MAF from the hose by unscrewing the Jubilee clip.

4) Remove the MAF from the air filter box, using a philips screwdriver (2 screws, 1 is hidden slightly) Once the screws are undone, you have to tug quite forcibly to pull the MAF away from the filter box. There is a large O-ring between the two, once separated check the O-ring to see if its in good condition. If its a bit knackered, get a replacement.

 

[Parrot of Doom]

This is the O-ring:

5) Once the MAF is separate, you'll be able to see what kind of condition its in. Mine was full of flies and muck. The inside of the MAF was also covered in a thin layer of oily muck. You can see the element at one end of the MAF, its protected by a plastic grid. Don't be tempted to touch the element at any time, its quite delicate.

Oily scum:

6) To clean the element, spray Isopropyl Alcohol onto it. I used just enough to get rid of the most visible contaminents. I also sprayed some around the inside of the MAF to help dissolve the oily muck that was there. I used kitchen roll to wipe this clean, although obviously I could only get to the first 2 inches or so. I sprayed on both the open side of the MAF, and the protected part of the element.

This is what came off the element:

 

[Parrot of Doom]

Now while I was doing this, I thought I might as well clean the pipe to the turbo, and the little pipe that heads off into the engine block. So I undid the jubilee clip holding the hose to the turbo, pulled the pipe from the engine block (it just slides out), and sprayed them both inside with lots of Isopropyl. Then I ran kitchen roll through them both and removed the oily slime from inside. You probably don't need to do this, but it can't do any harm.

This is the exposed turbo intake. Probably not a good idea to touch that

Utterly filthy pipe from the MAF to the turbo:

Once everything is dry, put it all back together in reverse order. Make sure nothing drops into the pipes when you're refitting.

Does it work? No idea. Haven't driven it yet, and its warm so the engine doesn't surge much this time of year. I'll let you know if the car's behaviour changes at all. Remember to give things time to dry, the alcohol should dry very quickly but if you saturate it and then put it all back together, the system will suck it through. Doubt it would do any harm whatsoever, but best to be safe.

 

[Parrot of Doom]

http://www.flickr.com/photos/soundman/

Bigger more detailed pictures can be found there.

 

[Blobcat]

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