How to clean your MAF

[Parrot of Doom]

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.

 

[Sprint'n'Go]

Oily scum:

Are you refering to the contents of the air pipe or the owner of the finger?

 

[malcolm E53 AMG]

Ever thought of producing car manuals, 10 out of 10 again. I hope your efforts solve the problem.

 

[television]

Very good, would there be any advantage in taking it out of the plastic housing to clean, when you buy a new one from bosch, it comes without the casing.

Malcolm

 

[Parrot of Doom]

I may just do that Malcolm, trouble is I don't have a decent set of torque drivers. The heads on the socket are quite badly corroded as well, looks like aluminium bolts, so I didn't want to try until I had the correct tool. No doubt when I get a proper torque driver I'll be able to take the MAF out of the case completely and give it a proper going over

 

[Flying Scot]

I may just do that Malcolm, trouble is I don't have a decent set of torque drivers. The heads on the socket are quite badly corroded as well, looks like aluminium bolts, so I didn't want to try until I had the correct tool. No doubt when I get a proper torque driver I'll be able to take the MAF out of the case completely and give it a proper going over

assuming you mean TORX not torque he he

 

[Parrot of Doom]

heh I always get that wrong

 

[television]

I found it interesting that Parrot cleaned all of the piping around the intakes, it was only a few days ago that I worked out the these things go down quicker on deisel on a post posted elsewhere. deisel is an oily fuel, where as petrol evaporates, whilst there is no direct contact with the fuel,there are the fumes when the engines is off that leave deposits, enabling the dust to stick on the sensitive sensor.
There is no mention of cleaning the pipes and duct work on the MB program, so I doubt that this ever gets done. Parrots info here is a good example of how you can do a much better job yourself than that of the MB service workshop.

Malcolm

 

[Ron Palfrey]

Who needs a manual when Parrot produces such excellent easy to follow procedures. 10/10 once again, and I've saved a copy on my PC for future reference.

Many thanks,

Ron

 

[Parrot of Doom]

Well its definitely improved the engine, no misfiring, no grumbling when idling, no hesitation, no surging.

Basically the engine acted like it was warmed up, whereas before when cold it could be a right grouchy bugger.

Worth doing, even if your car isn't giving you grief!

 

[Sprint'n'Go]

Am I right in assuming my 5cyl CDI diesel van will have a MAF sensor? From other threads the general opinion seems to be about 65k for the trouble to show up. Perhaps I have finally had some look here as my previous 311 CDI did 80k without trouble and my current 316 should still be on its original untouched sensor at 105k (I say should, as it has been in and out of the workshop so much that it may have been changed/cleaned without my knowledge).

Also from Parrots pics' there seems to have been a few flys and other debris flushed out. Isn't the MAF sensor on the clean side of the air filter? If so where have the bits come from? When I change the air filter on the van it always surprises me just how much muck is sat in the bottom of the filter housing, apart from the usual wasps, leaves and bits of washing sponge there is always a fair amount of sand/grit (probably 3-4 teaspoons full). However the filter has done its job and stopped progress further into the system. Could the level of contamination found on the MAF in this case point to a badly fitting air filter or faulty pipework connections.

Must be worth checking as I wouldn't like any amount of sand to reach the turbo then on into the cylinders.

Is it worth cleaning the MAF sensor as a service item during routine maintenence (perhaps every40-50k) or do I risk causing harm to a sensitive component which is best left alone unless a fault develops?

 

[Sprint'n'Go]

Well its definitely improved the engine

Worth doing, even if your car isn't giving you grief!

You beat me there, I was just posing the question to your answer!

 

[bibamus]

Excellent guide, can you get a job with Haynes? their pics are seriously useless! I cleaned my MAF ( `97 C180) using electrical contact cleaner last week. It certainly made a huge difference, not quite right, but I will give it another go this weekend.
Didnt clean the pipes though, they were spotless inside, I suspect they are all pretty new.
Now I just have to stop it pinking!!

Allan

 

[230K]

Parrot

Be careful when refitting the top onto the air filter cover, in the piccie you casing seems to be warped a little (like mine think heat of turbo does it) and this can cause the air filter element not to seat properly and let unfiltered air into the engine which your obviously getting if there were flies etc in you MAF. I think the air filter housing is a bad design on these im just never happy with the seal on mine.

230K

 

[Parrot of Doom]

http://mbclub.co.uk/forums/showpost.php?p=242875&postcount=15

 

[ALAN@ECUCLINIC]

i dont know wether this has been said but after seeing your rather mucky finger, can you imagine what the throttle body must look like? a thorough clean (whilst holding open the throttle) with carb cleaner generally does the trick. check tickover before and after...you be supprised.

 

[Royville]

Hi there,
Where can I find my MAF? I have looked every where on my c180 elegance and I don't seem to have one fitted. Is this correct for my car (1996)
Regards Roy.