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Started by Big_Richard, 12 December 2009, 04:21 AM


Since my interior is already removed, i decided it was time to "toughen up princess", and remove the air box for refurbishment, since I'm never likely to voluntarily be at this level of disassembly again  8)

Its actually not that hard - the only hard part is the stupid location of the A/C evaporator disconnectors. No idea how the hell anyone would ever change a TX valve with the dash and instrument cluster installed. What a freeking nightmare, even with the dash removed!


What pushed me into deciding to remove it, was the absolutely atrocious state of all the sealing foams in the box, be it the ones on the air flaps, or the ones that just seal things together. Its all screwed and turns to dust when disturbed.

I have since gutted it and have the housing in the dishwasher. 37c today with solar hot water plumbed straight to the thing, hope it doesn't melt! ;)

That's not a Mercedes being scratched by the box so chill-ax.  8)

This will be my project of the Christmas holidays I've decided to take, hopefully I'll be able to source suitable adhesive foam.

s class

you now officially qualify for the .ORG medal of bravery. 

[color=blue]'76 6.9 Euro[/color], [color=red]'78 6.9 AMG[/color], '80 280SE, [color=brown]'74 350SE[/color], [color=black]'82 500SEL euro full hydro, '83 500SEL euro full hydro [/color], '81 500SL


I have made a very important, disturbing and monumental discovery.


Poor air flow he says ???


This was after i started brushing some of the shit off, before i realised, hang on, maybe i should take a photo of this...

This evaporator looks very sad, it requires professional assistance in the way of cleaning it or its going to have to be replaced I'm afraid. And that's not going to be cheap considering left and right hand drive versions are different. So its genuine only. Not only was it 30% blocked by debris, it had a large amount of now deceased fury fungus growing most of the way across. Gross!

The whole duct behind where it sits and the first section where the blown air goes is a sanctuary for leaves and other shit to hide, where they will never ever leave..

And my airflow wasn't really that bad!

Slowly the parts are coming out of the dishwasher and looking like new.

Shame i cant put the evaporator in there ;)


I followed the service manual for complete disassembly, to the evaporator, the rest was pretty straight forward.

It mentions that there are 3 versions of the type 1 climate control air boxes, one early obsolete type, up to '77 with only 2 drains, and 2 later styles with the 4 drains. The late styles are either glued together & throw away items, or serviceable. The change happend at the end of 1978 with the 2 late types.

my car was built in 1978 but first registered as a 1979 car.

I stand corrected in that my airbox is the latest revision, the sealing cord referred to, is a non hardening sealing putty, and that there was plenty of. Thank god i didn't have the earlier glued type.


dear God,
what have you done!
what is poor TJ in for! i didnt realise you could pull these things apart?
i wasnt planning on pulling the one out of goldie for fear it would never go back but you give an ounce of hope it may be possible to clean this thing properly!
1979 116 6.9 #6436
2018 213 e63
2011 212 e63
2011 463 g55
2007 211 e500 wagen
1995 124 e320 cabriolet
1983 460 300gd
1981 123 280te


I'm wondering, where the hell do all the leaves come from, when there is a fine mesh under the anodised grill piece at the base of the windscreen. How is this possible - TJ showed me his spare research airbox, it also had leaves in it, but no where near as many as mine did.

It really was feral inside, I got black hands just handling the internals and that's not cool.

TJ 450

That was quite an effort on such a warm day, PB. 8)

There was a surprising amount of debris in there for sure. As for the mould and fungus, yuck!

Having had a look at the flaps, I don't think there is any such thing as a foam hinge per se, rather it looks as if the thickness of the foam is what keeps it wedged in the home position. The repair seems to be quite straightforward as long as the box is totally out of the car and disassembled.

It appears as if it would be just about impossible to do properly with the unit installed in the car.

1976 450SEL 6.9 1432
1969 300SEL 6.3 1394
2003 ML500


Quote un quote italians make cars in a logical italian sort of way the body they give you for free. sweeds make them to pass the moose test. british well we know where there car industry is now. the french make cars to be different from the rest of the world viva la diffence. and the germans believe that good hard work never hurt anybody ::)
Euro 6.9 255.6hp at the wheels. Watch this space.

TJ 450

Surprise, surprise,...

I'm actually thinking I should remove the airbox from my 450SEL now, as I would like to get the AC functioning as part of this revamp. Is this an approved activity Nathan & PB? ;)

BTW, that pretty well sums it up Motec6.9.

1976 450SEL 6.9 1432
1969 300SEL 6.3 1394
2003 ML500


Great work PB.

Yeah, how does all the rubbish get in there? The only holes in the mesh are where the washer jets are.

Tell us all what you end up using for foam.

There are non-OEM evaporators available, I got one for my wife's Peugeot but it wasn't a perfect fit, I had to cut parts of the housing away inside to get it in. Peugeot don't supply evaporators only the a complete HVAC unit.

Keep the pics coming.

Boogity, Boogity, Boogity, Amen!


at this point in time, I've NFI what I'm going to do with the evap coil.

I might have to research it further and find out what a new one will cost. After 7 years I'm really growing quite tiresome of shelling out big $ on this car and I'm reaching the point where I'm struggling to remain interested in the project at all.  :o

I'll attempt to wash this disgustingly filthy evap coil of mine to evaluate it, its black and makes my hands black just touching it. Someone was a very naughty boy and obviously smoked in the car, in recirculate mode.


A sample of what the dishwasher achieves with one single finish powerball cube  ::)

I spent a good couple of hours on this coil cleaning it.

Sealed it, then through 4 processes using a total of 200 litres of boiling water saturated with finish dishwasher powder have gotten it to this stage. All of the water was a black / very dark brown colour at the end of each hand wash.

The fine crap that was trapped deep inside the coil fins, never to see the light of day again was taken care of with a map gas torch, it obliterated all of that rubbish and it all came out when flushed with a high pressure blast of water at the end.

While not 100% aesthetically pleasing, it will work, and work ALOT better than it did before  8)

This was the disgusting side:

and this here was the clean inside side, now, even cleaner. The best part of all is that my hands don't get dirty anymore just from handling it.  :o

I'll have to get a coil brush to straighten out some of those fins...

I will be installing a filter between the fan motor assy and the airbox at the time of installation, I dont EVER want to do this again ;)

TJ 450

That's quite an improvement, to say the least.

I do hope that the Finish has been neutralised, though. ;)

1976 450SEL 6.9 1432
1969 300SEL 6.3 1394
2003 ML500


rinsed it off with plenty of water -

the only aluminium part is the fins, the actual coil is made of copper, not like today's ones  8)

the heater coil got the same treatment but it wasn't really dirty and very little came off.

That's also made to an impressively high standard, once again, unlike today's cars  8)