MAF cleaning - oil in air duct ??

Since buying my second 166 I have never been happy with the performance, especially compared with my first, both cars are yr2000 2.5 sportronic.

Symptoms are that altohugh the car revs freely right up to the limiter, there seems a distinct lack of power until 3.5-4K revs, this may be normal but it just feels a lot slower that my previous car, plus the car seems to fail to keep up with even the most normal cars !

Anyway after reading various posts on here, I thought I would try cleaning the MAF to see if anything improves.

First thing I found as I removed the air duct on top of the MAF was oil in the air duct itself where it connects to the hose connected to the injection unit, this was quite a lot, small puddles in the ripples of the hose. Is this normal ?

Secondly trying to remove the 3 bolts that hold the MAF body to the top of the air filter, I managed to shear one off, and the others are rusted up, so have stopped there. Question is can I replace the sheared bolt or do I have to replace the entire top of the air filter ?

Any comments on this would be great, because I am concerned about the amount of oil as I would not expect any. Cheers

think it's fairly normal as the oil breather goes into the air inlet there....it's what causes the rubber pipes to perish - a great design!

Ok, so whats to stop it getting into the MAF ?, I thought oil in the MAF was a problem, such as when using after market air filters

The main thing stopping oil from the breather getting to the MAF sensor is that the air is flowing in the opposite direction.

The quantity of oil and oil vapour from the breather will also depend on the quality of the engine oil used.

The 2.5V6 does have a very strange torque curve too, so can be lacking at low revs.

Re. sheared bolt on air filter housing. I had this problem too - all the cross head screws were v. rusty and one sheared.
I fixed this by making a new threaded insert for the bottom section of the housing. I cut a short piece of an M10 brass screw and drilled and tapped an M6 hole down the centre. I then screwed this insert into the bottom housing with a bit of Loctite for good luck. I fitted new M6 allen head screws and assembled with anti-sieze compound.

If you are getting a lot of oil in the hose, it's coming from the crankcase vent. The vent is connected to an oil separator on the plenum and this separates any liquid oil from whatever comes out the vent. The oil drains back to the crankcase. Anything that does not drain back is fed into the air path and gets burnt.

If the 164 is anything to go by, the drain tube for the oil return frequently gets blocked and so more oil gets to enter the induction path. A modification was made to the late 164 24V engines that increased the size of the return tube - presumably to reduce this problem.

Take off the separator (on the 164 it's a black painted thing at the back of the plenum, with three rubber hoses attached and held by 2 screws, 10mm heads). Fill the thing with paraffin, thinners, petrol and shake vigorously for about a day to try to wash out the brown crud that accumulates inside - you can't open it. Helps to have an air line. Carb cleaner might do the trick here. It's an easy job but mucky and might help alleviate the problem. Clean out the return hose and its connection to the crankcase too (difficult to reach on a 164 and probably worse on a 166!)

Looking at the parts manual and at the image here, it seems that the oil vapours do not go back to the big hose as they do on the 164. Can't tell where the connection to your big hose comes from.

Anyway I hope some of the above is of use.

Hi just athough and sugestion try not to clean your airflow sensor with anything as this can and does cause damage to the NTC sensor you should clean it by using a camera blow brush and be gentle while doing it Alfa them selves advise strongly that any solvent used to clean the sensor will cause it to possibly give incorrect signals to the engine ecu for injection duration, at the sort off rev,s your discribing it also souds a bit like possible Lambda fault, hope this helps?

Hi MickT Mine is the same....Good tips from Ken and Mudhut,When the weather gets better i'll investigate .

Thanks for all your posts certainly somthing to go on..

Originally Posted by mudhut

If you are getting a lot of oil in the hose, it's coming from the crankcase vent. The vent is connected to an oil separator on the plenum and this separates any liquid oil from whatever comes out the vent. The oil drains back to the crankcase. Anything that does not drain back is fed into the air path and gets burnt...

Yeah but only for Euro2 V6 engines, mine 2.5 V6 Euro3 does not have this separator ... I think.
One hose from front V bank is connected before butterfly valve to rubber hose and second from rear V bank to aluminium intake plenum.
In the front bank pipe is inserted one way valve vith very limited flow into engine.

And BTW this separators are crap for cars doing short trips.
I have to remove this from my mums Alfa 75, bacause it condensed moisture from the engine and aded more and more water into the oil (in winter time).
Becuse of that it rusted inside (separator) and all kinds of crap were sucked trough buterfly valve into engine. Eventually it get idlig problems, so i cleand the whole lot, removed separator, directly connected pipes and now everything is OK. A bit oily but clean butterfly valve.

Edit
Ow yeah I have to do something with my MAF too (no oil in hoses), becuse my Bella is acting a bit funny.
Probably buy a new one.

Originally Posted by MickT

Anyway after reading various posts on here, I thought I would try cleaning the MAF to see if anything improves.

here you go dude...


Remove the MAF - undo the metal clips with a pair of small pliers or lever off with small screwdriver, undo the cable tie which keeps the connector cable tidy to the air duct.and then the connector remove the MAF.

There are 2 TX secrurits screws that clamps the sensor to the MAF body...these can be undone with pliers as they are not to tight.

Pull the sensor head out and stick the MAF body a bowl of luke warm water and slosh about...use a sponge to clean the inside of the MAF body but do not touch the Mesh. then put back in the bowl and leave for about 20 Mins...

To clean the sensor head you need anti-static cleaner from Maplin or any radio hobby store..

Spray liberally all over the head......

You will see a channel in the sensor head, and will notice a wire running inside....you can clean this with a cotton swab with cleaner applied.....don't go to mad just apply gentle pressure.

At the side of the sensor is a metal plate within another channel...you can clean this using the cleaner and some tissue, wedge it in the grove and slide in and out....you can use a small screwdriver to exert more pressure to clean the plate and the edges.

The sensor heads..electonics is sealed so don’t worry too much...but still be careful.

When this is done....rinse the sensor head under luke warm running water from the tap and just cover the top part of the head where you have cleaned...

when done remove the MAF body that was soaking, test the mesh for cleanness with a cotton swab, if still dirty use the anti-static cleaner to clean more..and re wash in luke warm water.

Lay both the sensor and the MAF body...on a tea towel on a radiator to dry naturally...

Re-Fit the MAF all back together and put back on the car.

Thanks mikebrown, found this post already though thats what I was working to when I sheared the bolt

In my opinion having tried to clean the Maf on my car, this cleaning is absolute nonsense.

Buy a new Maf (genuine from Alternative Autos).

I ****ed around for 4 weeks doing this and cleaning it again and again. I bought spurious Mafs (got my money back too) and even second hand ones off ebay.

Once I got a new one my TS was transformed and the Engine light no longer comes on every 80 miles or so.

Hope this helps.

Richard

Would be interested to hear from others who have tried cleaning the MAF, and whether they saw a difference.

I should point out I have no warning lights on (lucky me), and the engine seems to run OK, smooth and revs to the limiter, but as I first stated the power just seems to be lacking. Could it be something other than MAF, maybe plugs, leads etc, the car has done 67K, and I am not sure if the plugs have been changed.

Originally Posted by mudhut

Looking at the parts manual and at the image here, it seems that the oil vapours do not go back to the big hose as they do on the 164. Can't tell where the connection to your big hose comes from.

Of course any oil left at shutdown will seep past the butterfly & into the big hose - it may only be a cc or 2 a time, but it'll add up.

Hello mudhut
Did you get the diagram from a CD? If so how do you do it. My CD does not seem to have a print facility.

Hi - it's a kludge really.

Grab the screen from ePER with the "Print Screen" key. Start photoshop (Photoshop Elements 2 in my case) and create a new file from the clipboard (there's a menut item for this in the File menu). Crop as desired then save as a fairly low res JPEG - I used quality 4 or 5 I think.