There is a large module on the left side of the firewall on my 450 SEL that has a bunch of vacuum hoses going to it, and 4 coolant hoses. The module is leaking coolant when I shut the car off.

I am assuming that it has something to do with the heat and climate control. My question is this: What is it and what is involved with repairing and/or replacing it.

Thanks people.
Jeff

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1978 450SEL (Pearl white, bamboo interior, 97k)
1959 Impala (2 dr. Hardtop, red, white int., 283 V8, 45k)
2003 Tiburon GT V6 (Ultra Sports Pkg. 3, red, blk int., 13k)

Automatic Climate Control brain box that uses vacuum controled mechanical solenoids relying on electronic thermo-switches instead of straight cable manual linkage?

I've heard that piece is genuine work of art...... probably $600 off the shelf.

On the manual system a coolant leak there is not uncommon, indicating bad rubber seals on the valves alot like hydraulic master cylinder seals - easily repaired.

Disassembling the ACC brain box sounds like a wonderful project, but I'll betcha it's just the rubbers causing leakage.

four50 -

You have discoverd the fabulous ACC Servo. If you are lucky, you have a leak at a hose.

Clean it off real well to find out. That servo is famous for cracking. Cracked = replace. Replace = $$$.

I think Fastlane and others offer an electornic replacement for less than a new servo (sorry purists) without the certain demise of a new servo after a couple of years.

Search here on the servo or Chrysler ACC I.

Kevin

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"Dangerous with a wrench...and not smart enough to know it"

Stable (in order of acqusition):
'84 500SL, 280SEL (Euros)
'77 280SE. '90 560SEL
'79 450SEL 6.9,
'95 C280 (totalled by daughter 8/07)
'81 280SL (rescued) '88 300CE
'86 560SEC '95 C36
'01 CL55

DD's: '04 S500 4Matic (SWMBO)
'04 F150 Crew

Damned, isn't that my luck. At any rate, it has stopped leaking. For the time being, at least. I'm sure it will start up again at some point. I'll take it apart to see what the hell is going on. Thanks, all, for the help.

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1978 450SEL (Pearl white, bamboo interior, 97k)
1959 Impala (2 dr. Hardtop, red, white int., 283 V8, 45k)
2003 Tiburon GT V6 (Ultra Sports Pkg. 3, red, blk int., 13k)

I'd follow Kevin's advice and replace it as soon as possible with the electronic version. Many many engines have been replaced, because this servo leak went unnoticed while driving. By the way unless they moved it that servo should be near the right front fender.

Peter

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Auto Zentral Ltd.

I have a cracked servo and am wondering if I should go the used servo route or look into the electronic replacement. What parts would I need, how much would it cost, what kind of mods. would I need to make? Good used servos are $100-200 on ebay.

You can put in a used servo, and you are still dealing with an engineering oiece of junk. The electronic unit is around $500 I believe, but far superior in design. If you are selling the car go used, but if you're keeping it, go for the electronic unit.

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Auto Zentral Ltd.

Who sells the electronic replacement? Are they on Fastlane? How easy are they to install? The unit that is in the car has a manuf. date of 1977 which is the same year as the car. Is there any way that it could be the origional?

I got super lucky and picked one up from a junkyard for $50. The thing was almost new! Came out of a wrecked '80 (mine is a '79). Check your local yards to see what you can find.

Good luck

~Rich

Congratulations, but you still have a piece of junk. The electronic replacement is the way to go. Trust me. I've worked with this POS system since it came out.

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Auto Zentral Ltd.

Um, there is a link at the top of this very page for an ACCII kit that replaces a servo with an electric solenoid.

Might not be for your version though.

Michael

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Usta haves '69 250/8, '76 280C, 1971 250C 114.023, 1976 450SEL 116.033
Current have, 1983 300SD 126.120

Thats kinda harsh there buddy. Did you not get your nap today? I'm fully aware that the OEM stuff is not the best example of engineering to come from Mercedes. But a fully functional, non leaking servo that has worked for the past 4 years is not considered junk. Especially at $50. I consider this a damn good find, and a MUCH cheaper alternative to the electric conversion.

~Rich

What is the cheapest and simplest route? Not always the best or longest-lasting. For some people, buying an expensive ($500?) system to replace the servo isn't sensible, as it might outlast the car. It's similar to the transistor ignition - you can convert to a crane/petronix if the original dies, or you can go to the junkyard and pick up a used, working box for $5. Said box has lasted me 4 years.

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Current:
2021 Charger Scat Pack Widebody "Sinabee"
2018 Durango R/T

Previous:
1972 280SE 4.5
2014 Jeep Grand Cherokee Limited "Hefe", 1992 Jeep Cherokee Laredo "Jeepy", 2006 Charger R/T "Hemi"
1999 Chrysler 300M - RIP @ 221k

First of all the OEM stuff was not engineered by Mercedes. THey bought the system from Chrysler. Secondly the chrysler system was only a mild improvement to the original flap system designed for the 116 and 107 cars. Those servos have destroyed many engines by splitting and leaking water while driving. Since those were the days before low water level warning systems, lots of drivers found out they had a major water loss when the temp needle on the dash PEGGED. Also the little water pumps on that system start drawing too much current and burn out the amplifier.

If were selling one of those cars, I'd put in a used unit. If I wanted to keep the car, I'd buy an electronic conversion.

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Auto Zentral Ltd.

I have been looking for used servos on Ebay and by the time I buy a servo and amplifier I would be close to the price of an electronic unit. There is not a whole lot of info from people who actually have them in there cars. Are they the cure all that they claim to be? They are about $150-200 cheaper on ebay. Does anyone know if they are the old units they claim that they are the H version and the latest update.