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Garage => Mechanicals => Topic started by: Tony66_au on 28 September 2012, 03:51 AM

Title: D jet Aux Air Valve refurb ( AAV )
Post by: Tony66_au on 28 September 2012, 03:51 AM
This is a copy n paste from the thread I created on another forum.

Hope it is helpful.

I've recently had a shot at refurbishing my AAV for my D jet 450, The AAV is common to the 280/350/450 M116/M117 in both D and K jet and I believe the AAV's themselves are the same.
 
 So I've collected up my ramblings and pics and im placing them here as an easily searchable resource.
 
 Feel free to add your 2 cents worth and correct me if im wrong.
 
 Cheers,
 Tony
Title: Re: D jet Aux Air Valve refurb ( AAV )
Post by: Tony66_au on 28 September 2012, 03:53 AM
THE TESTING!
 
 One x Pyrex high temp glass jug
 
 One x Meat thermometer
 
 Boiling water, add AAV to taste.
 
 (http://i24.photobucket.com/albums/c35/tony66_au/Merc/GEDC1737.jpg)
Title: Re: D jet Aux Air Valve refurb ( AAV )
Post by: Tony66_au on 28 September 2012, 03:54 AM
The method is simple, fill glass jug to 75% with boiling water, place thermostat in jug and check temp.
 
 (http://i24.photobucket.com/albums/c35/tony66_au/Merc/GEDC1738.jpg)
 
 Place AAV in hot water making sure to NOT get the insides wet.
 
 Using the torch check the progress of the slide.
Title: Re: D jet Aux Air Valve refurb ( AAV )
Post by: Tony66_au on 28 September 2012, 03:56 AM
A few traps to observe, I am told the valve should not allow air to pass @ 66 Celsius.
 
 This usually means putting your lips to the AAV and sucking or blowing,
 
 Problem #1 is that the AAV is currently at or around 80 Celsius so I liberated the short air hose and left it on the unit .
 
 Problem #2 is more of a cautionary note as your AAV is likely still contaminated with brake cleaner or degreaser which is toxic at normal temps and very much so at near the boiling point of water so resist the urge to suck test the valve.
 
 Sadly my valve didnt seal shut as the picture has shown so my next task is to pinch the bulb in the bottom of the AAV and retest in hot water which im told works "Sometimes".

The bulb is a bugger to squish even a little bit BTW
Title: Re: D jet Aux Air Valve refurb ( AAV )
Post by: Tony66_au on 28 September 2012, 03:58 AM
 Testing phase over we go to cleaning the AAV
 
  Ok, this after noon I removed my AAV for testing Pn# 0280140017.
 
 2 x 4mm hex screws held it in place and when she popped out of the jacket I lost half a cup of coolant and no more.
 
 I gave her a quick squirt of brake cleaner to get rid of any grunge on the outside and wiped the bulb on the bottom clean so it was ready for testing.
 
 I noted that the bulb has -30 celcius stamped on the bottom, any idea what that's about?
 
 Anyway, with a kettle full of boiled water, a pyrex jug and my thermocouple and multimeter telling me the temp was @ 90 degree's I immersed the bulb and base of the AAV in the water and watched the slide to see if it closed by blowing down the outlet.
 
 Yes the slide moved to almost closed but air still freely passed through the valve even though it was now too hot to hold in my hands.
   
  So the unit is faulty and slow to move.
 
 Next step meant back to the bench where I had a few cans of brake cleaner and some parts wash along with an empty 5 lt oil bottle with the side completely cut out.
 I usually try for a nice bright colour but today all I had was a grey bottle as the colour helps to show how much crap is being washed out of the part you are cleaning and I wasn't disappointed with a fair amount of fine black dust washing out into the oil container.
 
 BTW I alternated between the cheapy degreaser @ $2 a can and the brake cleaner to get good results with a bit of a soak.
 
 Why? Because brake cleaner evaporates quickly and degreaser does not.
 
 Ive also used a trans fluid 1 lt bottle to soak the AAV fully immersed in parts wash fluid and tomorrow after a blast out with brake cleaner and then compressed air I will test the closing and speed again before going to step 2.

  Day 3 and more soaking overnight, I removed the AAV from the wash and gave it another blast of brake cleaner washing out a substantial amount of  fine black grit before dropping the valve back into the wash, tomorrow I give it a final clean with brake cleaner and leave it to dry before another 80 celcius dunk test, if that fails to close the valve all the way I will try pinching the bulb in the vice or with vice grips to see if that method works and retest again!
 
 Tony
Title: Re: D jet Aux Air Valve refurb ( AAV )
Post by: Tony66_au on 28 September 2012, 04:02 AM
 The semi finished product, back to testing the unit!
 
 
 
 
  Finished soaking the AAV a few hours ago and well and truly blasted out the unit with brake cleaner so there is nothing but cleaner coming out of the unit now.
 
 Uploading a few piccies I took as I type this and I will post them shortly.
[/t][/t]   
The Aux air valve after cleaning.
 
 (http://i24.photobucket.com/albums/c35/tony66_au/40988da5.jpg)
 
 (http://i24.photobucket.com/albums/c35/tony66_au/ff161c8e.jpg)
 
 (http://i24.photobucket.com/albums/c35/tony66_au/ac3c779b.jpg)
Title: Re: D jet Aux Air Valve refurb ( AAV )
Post by: Tony66_au on 28 September 2012, 04:04 AM
And a quick M117 D jet mug shot!


 Excuse the grubbiness
(http://i24.photobucket.com/albums/c35/tony66_au/GEDC1706.jpg)
Title: Re: D jet Aux Air Valve refurb ( AAV )
Post by: Tony66_au on 28 September 2012, 04:06 AM
A reliable source (MBGraham) tells me a new AAV should be fully closed @ 66 Celsius and Ive edited my posts to reflect the correct temp.
 
 I've pinched the bulb twice now with vice grips adjusting them up half a turn and closing them, opening them and repeating @ half a turn.
 
 The result is that at 80 degree's the AAV is almost shut with a fair restriction when I blow through the valve.
 
 So its back to pinching the bulb but this time im shooting for a lower closing temp of 66 - 70 Celsius......
 
 Tony

This evening late I reinstalled the AAV using sensor safe copper maxx hi temp silicone and a new graphite gasket I cut from a sheet of gasket paper.
 
 Topped the coolant off with 500 ml or so and turned the key.
 
 I noticed the temp graduation on the guage is in 20 Celsius increments and just in the 60 degree mark the high idle started to come down until at a needles width past the 60 mark she settled for a nice resting RPM rate.
 
 Test run minus air cleaner assy fitted and without the sensor in the air cleaner assy attached, Idle tested with AC on in neutral, park, drive and reverse and its all solid although probably a smidge low loaded up.
 
 Checked the idle screw and it has been screwed fully clockwise already so I cant lower the idle there anymore and turning it anti clockwise raises the idle speed so I suspect the system is out of whack somewhere probably during an attempt to drop the idle before I got the car.
 
 All in all a good result!

I should pull a dud AAV apart some time I guess but my understanding of how it works is that the brass bulb that sits in the coolant has oil in it that expands with increase in temp and this pushes the piston up in the bore of the valve reducing the air flow.
 
 I suspect the spring just keeps the piston square in the bore so it is less likely to jam and to aides in the return of the piston to fully open as the coolant drops in temp and that this expanding oil or fluid weeps past over time making the reaction to heat slower and less effective.
 
 So the simple action of crushing the bulbs a bit restores the static pressure to what it should be to operate effectively.
 
 This is further backed up by the pictures I've seen of factory refurbished AAV's having 4 neat uniform indents on the bulbs.
 
 The refurb is fairly simple and cost me 5 cans of Repco degreaser and a full can of brake cleaner so under $30 and maybe 3 hours over 4 or 5 days once the AAV is removed with an hour of static testing with a jug and hot water.
Title: Re: D jet Aux Air Valve refurb ( AAV )
Post by: scraf on 28 September 2012, 11:58 AM
Hope it is helpful.

 Tony

VERY helpful ! ( although had already read this at the other source, just wasn't registered to comment )

Scored an AAV a couple of days ago, travelled 40km not to buy a rusted out headlight for my W114, while I was there I extracted the AAV for the grand sum of € 10,-.

It's exactly the same one as you've documented ( D-Jet ? ), but as far as I can tell it will only need a change of pipes and it will fit on my 450 SEL K-Jet.

The AAV closes completely when tested in boiled water, am going to invest in a meat thermometer tomorrow to see if I need to do any bulb squeezing to get it to the 66 degree optimal.

MANY thanks.
Title: Re: D jet Aux Air Valve refurb ( AAV )
Post by: Tony66_au on 28 September 2012, 05:26 PM
My pleasure Scraf, D jets are perceived as a black art to maintain and repair and im buggered if I know why because they are far closer to modern EFI than bloody K jet is lol.

Id also like to add that these AAV's are fairly substantial as a heatsink and as most kettles dont actually bring water to 100 Celsius id consider microwaving the water, dunking the AAV base in the water until it heats up and then checking and possibly reheating the water again as it does drop in temp significantly.

Also I have conflicting reports on the closed temperature of the AAV when functional and my theory is that some may open for different temps due to climate variations in the marketplace in the same manner as Mercedes have tropical spec cars etc.

That said 66 degrees Celsius seems a good middle ground for D jet cars operating outside the Arctic circle.
Title: Re: D jet Aux Air Valve refurb ( AAV )
Post by: Tony66_au on 28 September 2012, 05:35 PM
Im flicking through my photos from the refurb looking for a pic of the AAV fully closed showing the slot that remains open to allow air to flow through at a greatly reduced rate.

But here's one clearly showing the temp 66 Celsius = 150 Fahrenheit

(http://i24.photobucket.com/albums/c35/tony66_au/Merc/GEDC1736.jpg)

Title: Re: D jet Aux Air Valve refurb ( AAV )
Post by: Tony66_au on 28 September 2012, 05:38 PM
Here tis!

After refurb, yes the temp is higher than 66/150 as it was before I squished the bulb to bring the wax pressure back to near normal.

Note the slot at the top of the slide piston allowing air to pass although fully closed.

K jet AAV's I have played with seal off completely.


(http://i24.photobucket.com/albums/c35/tony66_au/Merc/GEDC1741.jpg)
Title: Re: D jet Aux Air Valve refurb ( AAV )
Post by: thysonsacclaim on 29 September 2012, 12:44 AM
Excellent post!
Title: Re: D jet Aux Air Valve refurb ( AAV )
Post by: Tony66_au on 02 July 2013, 02:01 AM
Bumpitty bump!

Might be worth making this thread sticky?
Title: Re: D jet Aux Air Valve refurb ( AAV )
Post by: TJ 450 on 02 July 2013, 04:01 AM
I concur with that.

Tim
Title: Re: D jet Aux Air Valve refurb ( AAV )
Post by: djenka018 on 14 September 2013, 08:21 PM
As a further confirmation of previous statement:

Mercedes D-Jet EFI training manual dated back to early 70's commands that AAV has to be fully open @ -20*C and fully shut at 65*C (149*F).


(https://www.dropbox.com/s/vix6tag56l0btyr/2013-09-15%2013.12.46.jpg)

https://www.dropbox.com/s/vix6tag56l0btyr/2013-09-15%2013.12.46.jpg (https://www.dropbox.com/s/vix6tag56l0btyr/2013-09-15%2013.12.46.jpg)
Title: Re: D jet Aux Air Valve refurb ( AAV )
Post by: Tony66_au on 13 October 2013, 04:20 AM
Ta for the clarification djenka,

I have come to realise that the AAV seems to cause an awful lot of issues when not maintained and even more issues when people try to work around it re idle RPM.

Such a simple fix too!

As a further confirmation of previous statement:

Mercedes D-Jet EFI training manual dated back to early 70's commands that AAV has to be fully open @ -20*C and fully shut at 65*C (149*F).


(https://www.dropbox.com/s/vix6tag56l0btyr/2013-09-15%2013.12.46.jpg)

https://www.dropbox.com/s/vix6tag56l0btyr/2013-09-15%2013.12.46.jpg (https://www.dropbox.com/s/vix6tag56l0btyr/2013-09-15%2013.12.46.jpg)
Title: Re: D jet Aux Air Valve refurb ( AAV )
Post by: djenka018 on 13 October 2013, 04:44 AM
Ta for the clarification djenka,

I have come to realise that the AAV seems to cause an awful lot of issues when not maintained and even more issues when people try to work around it re idle RPM.

Such a simple fix too!

As a further confirmation of previous statement:

Mercedes D-Jet EFI training manual dated back to early 70's commands that AAV has to be fully open @ -20*C and fully shut at 65*C (149*F).


(https://www.dropbox.com/s/vix6tag56l0btyr/2013-09-15%2013.12.46.jpg)

https://www.dropbox.com/s/vix6tag56l0btyr/2013-09-15%2013.12.46.jpg (https://www.dropbox.com/s/vix6tag56l0btyr/2013-09-15%2013.12.46.jpg)

I mean to scan this training manual and post it here.
It is solid gold in terms of understanding the D-Jet engine management. Most of it is documented in country specific (or properly named: national version) printed manuals but some of them are not readily available.
Title: Re: D jet Aux Air Valve refurb ( AAV )
Post by: Tony66_au on 13 October 2013, 05:03 AM
worth scanning for sure.

Once understood the system is quite simple
Title: Re: D jet Aux Air Valve refurb ( AAV )
Post by: 1974450SEL on 20 October 2013, 01:07 PM
Tony,
    This is a great write up.  After 8 years of a surging idle (till it warms up) I've decided to take on this challenge.  I've successfully removed the AAV, minus one broken Y house (I just ordered new AAV hoses from Pelican parts).  I'll have to find replacement screws since I (feeling so good about uninstalling it) misplaced them.  Thanks for posting this and I'll keep my progress posted.

Brian

Portland Maine
Title: Re: D jet Aux Air Valve refurb ( AAV )
Post by: Tony66_au on 20 October 2013, 04:25 PM
My pleasure Brian,

One of the most commonly neglected service items sadly and little info out there for a simple refurbishment plus brand new D jet AAV's are hard to come by and K jet AAV's are expensive.

Good luck and keep us posted on the results.

Cheers,
Tony
Title: Re: D jet Aux Air Valve refurb ( AAV )
Post by: 1974450SEL on 27 October 2013, 06:21 PM
Tony,
   Well a week into the adventure, I've followed just about all steps and have the valve to the "nearly" closed position  while is boiling water as shown in your last photo but air still passes through.  I have it soaking in Trans fluid tonight.  Previously have used degreaser and brake parts cleaner and have had some black gunk come out.  I've tried squeezing the bulb and it is a S.O.B.  I reread your write up and see you've used vice grips, I've been using just needle nose pliers.  I'll keep you posted about tomorrow's results.  I've not had access to a thermo but can borrow one from my mother n law. 
Title: Re: D jet Aux Air Valve refurb ( AAV )
Post by: Tony66_au on 27 October 2013, 08:36 PM
A few points
meat thermo is under 10 bucks and will make your Thanksgivings day safer too!

The AAV's dont close off completely especially the K jet units

Dunno about the trans fluid soak, Parts cleaner is cheaper.

And yep you will get trace amounts of carbon from the AAV for a few cleans which was why I usually flushed em out with brake or carby cleaner into a white container so I could see how much carbon was left.

AAV should be shut at the temp mentioned above (Air will still pass through though) and no need to nip the bulb unless its not closed at 60 ish (150f )
Title: Re: D jet Aux Air Valve refurb ( AAV )
Post by: 1974450SEL on 28 October 2013, 07:50 AM
Well,  after the soak and a shot of degreaser and brake cleaner it does fully close now at the proper temperature. It is good to now air will still pass through, that had me worried.  Now on to installation, I have found one screw underneath the car with a long magnetic tool (best purchase next to meat thermo) I can go to the hardware store and try to find a 2nd screw to match.  Keep you posted on how she runs.  Thanks again!!
 :)
Title: Re: D jet Aux Air Valve refurb ( AAV )
Post by: Tony66_au on 06 February 2014, 05:04 PM
Once again my pleasure,
I am currently working on a better tutorial to add the info people have clarified and corrected for me and I have a few other D jet tricks I have yet to document and verify.
I am not a mechanic by any means and my approach to repair can be a bit slap dash and half arsed however working with my German toys I have found that it is always best to do it right and with solid information on the project at hand.
I also believe that if you give Bosch GMBH a wheelbarrow load of cash they will refurbish and return your AAV in an as new state as well as MPS's etc and if you are happy to spend some money and wait a month or so id recommend you take this path if your own attempts at a refurb are not to your expectations as not all AAV's come up 100%.

Finally id like to add some observations on common issues and their effects with the main issue being air bleed idle screw fiddling NOT being a cure or work around for a Dud AAV and as im currently finding with a D jet 350SE removal of the cold start system causes more problems than it allegedly "Fixes".

As mentioned elsewhere the whack it with a hammer "Fix" is for the larger K jet AAV's and finally ignoring the idle RPM must do horrible things on a cold start as the RPM I have seen was in excess of 2000 rpm AND on 2 of the cars I have seen decidedly groaning torque convertors which I found to be broken vanes in one instance being a bit under 50% and id hate to see what the damage to the clutch packs are.

All in all folks?

Fix it.
Title: Re: D jet Aux Air Valve refurb ( AAV )
Post by: atatexan on 06 February 2014, 07:28 PM
I am following this thread with great interest. My Austrian 350SE, a US resident since 1984, has a rebuilt/returned AAV (by Peach Parts CA subcontractor). It still surges at idle when cold. I can't see that it moves at all!

Am staying tuned to this thread.
Title: Re: D jet Aux Air Valve refurb ( AAV )
Post by: Tony66_au on 06 February 2014, 07:49 PM
Sounds like it may be a TPS or Vac leak somewhere.

Read this thread for a better understanding of D jet, its piss easy to understand.


http://forum.w116.org/mechanicals/how-it-worksbasics-of-the-d-jet-injection-system/
Title: Re: D jet Aux Air Valve refurb ( AAV )
Post by: atatexan on 06 February 2014, 08:12 PM
Hopefully not the TPS. Bought new foil piece from a guy on the Porsche 914 forum.

If I used the throttle after a cold start to override the surging, idle levels out after 3-5 minutes.

Thank you for the quick reply from Oz.
Title: Re: D jet Aux Air Valve refurb ( AAV )
Post by: Tony66_au on 06 February 2014, 09:02 PM
Not a problem and i hope it helps!
Title: Re: D jet Aux Air Valve refurb ( AAV )
Post by: WGB on 06 February 2014, 11:53 PM
This is an old photo that I posted many years ago when I purchased a new K-Jet AAV valve for my 1979 450SEL.

It suffered from a slowly decreasing idle on a very hot day when run up in the hills and would not idle at all after being parked with a hot motor but was fine when cool but with a slightly erratic idle.

(http://rs257.pbsrc.com/albums/hh219/WGB_album/OldandNewAuxillaryairvalves.jpg~c200)

This must be one of the last AAV's sold new and shows new and old in the same cup of water.

The K-jet type is a straight through from side to side configuration while the d-jet comes out the top via an elbow in the casting.

Bill
Title: Re: D jet Aux Air Valve refurb ( AAV )
Post by: Tony66_au on 07 February 2014, 02:09 AM
Thanks for that Bill!

Photos always welcome
Title: Re: D jet Aux Air Valve refurb ( AAV )
Post by: Tony66_au on 18 August 2019, 04:14 PM
Worth reading through the WHOLE thread as the comments add some details and correct some specifications I got wrong in the initial post, Aux Air Valves are never completely closed off for example and yet I refer to them being so.
As D jet AAV's are Unobtainium it is worth refurbing and shelving one for the future, K jet AAV's too are difficult to come by but you do see professional refurbished units pop up from time to time.
Title: Re: D jet Aux Air Valve refurb ( AAV )
Post by: UTn_boy on 18 August 2019, 05:15 PM
Worth reading through the WHOLE thread as the comments add some details and correct some specifications I got wrong in the initial post, Aux Air Valves are never completely closed off for example and yet I refer to them being so.
As D jet AAV's are Unobtainium it is worth refurbing and shelving one for the future, K jet AAV's too are difficult to come by but you do see professional refurbished units pop up from time to time.

Well, not exactly.  D Jetronic idle air slides are still available new from Mercedes.  Part number 000-141-03-25.  Though, they list for $755 USD.  I imagine in Australia they'd be double that amount. 
Title: Re: D jet Aux Air Valve refurb ( AAV )
Post by: Tony66_au on 18 August 2019, 11:37 PM
Weird but good, I checked a number of years ago and they where listed NLA although the K jet AAV's where still available.
Thanks for the heads up.
Title: Re: D jet Aux Air Valve refurb ( AAV )
Post by: UTn_boy on 19 August 2019, 04:08 PM
You'd be surprised at how ma y dealerships will tell you a part is no longer available simply because they

1) Don't know that they have to contact Classic direct
2 Don't know enough about the older models to find parts in the book or EPC
3) Don't know that Mercedes offers parts for any model over 10 years old
4) They're too biased to want to have anything to do with the older models. 

You pretty much have to take the proper part number to them, put it in their hands, ask them to order that part number, and if they say they can't then inform them that they should contact Classic direct AND check the availability on Paragon in order to see that, in fact, there is stock available. 
Title: Re: D jet Aux Air Valve refurb ( AAV )
Post by: Tony66_au on 19 August 2019, 04:23 PM
Ive struck that before yup but usually try to avoid Aussie Benz dealer parts due to the horrific markups.

That said the guys I use have bought parts from Germany before for me and im always armed with both the MB and OEM parts numbers (An FAG brand rear wheel bearing for a 230TE 124 chassis $780 plus freight from Stuttgart that I sourced from MB Spares in Canberra later that day for $124 plus freight overnighted lol)

Classic Center in Irvine Ive told them about as well but I suspect that at the time it had something to do with MB's war on grey market parts.
I dont blame the dealers for the price hikes either as their pricing is firmly set by MB Australia but its nice to know that the parts are now available.

I do know the Bosch do limited parts runs and refurbishments every so often too and this has come in handy for my 1973 SLC.