'78 300D ACC Servo leak - Anyone ever try fixing one? - PeachParts Mercedes-Benz Forum

rgnprof · #1 11-30-2006, 07:03 PM

First winter with this car and no problems with servo until today. I have read all of the posts and am aware of my options - replace, bypass, etc. But I have another question: anybody ever tried to fix these things themselves?

Mine is not cracked, at least not anywhere that I can see but it is leaking coolant at what looks like a place where it is - or should - be joined by a gasket of some sort. Anyone ever take one apart and try their own repair?

My defrost worked fine but I lost vacuum as well and neither AutoHi or AutoLo would work and the car wouldn't shut-off, so I'm sure this is related to a vacuum leak somewhere.

Ryan

Moorewr · #2 11-30-2006, 07:10 PM

is yours leaking between the water ports and bottom of servo, mine did years ago and I found a bottom, fixed for a while, but alas just went to the unwired
replacement and fixed the whole mess. vac leaks are a nightmare unto themselves?

I have a friend who is going to take my old servo apart to see if it can be fixed, seems I saw a thread in here somewhere where some had fixed one.

No help, compassion?
Ron

unkl300d · #3 11-30-2006, 08:54 PM

Hey give it a go !! Let us know. There was a thread similar to this. The guy did succeed to an extent but he was careless in the assembly and broke an internal spring-plunger thing.

good luck.

Mail the mess to me for target pratice!

kerry · #4 11-30-2006, 09:11 PM

You might try surfing some Chrysler Imperial websites for an answer since this evil was also inflicted on those cars.

carnut · #5 11-30-2006, 09:13 PM

This servo was used on early 70's Chrysler cars with automatic climate control prior to MB adopting it.

rgnprof · #6 11-30-2006, 11:20 PM

Is my vacuum problem related to this servo leaking? I can not shut off the car with the key - the servo is running but I think the reason I'm not getting any heat on AutoHi or Lo is vacuum related??? Where should I look?

ryan

unkl300d · #7 12-01-2006, 12:03 AM

Track your vac problem and fix it. start fresh from there.

You don't shed enough details for folks to chime in.

aside:
Funny how Chrysler marked the low of Mercedes even back in the 1970's!!!
Fast forward.

rgnprof · #8 12-01-2006, 12:33 AM

I'm not sure what other details to include - all the vacuum stuff has been working fine for months - ACC, door locks, shut-off, etc. Servo just started to leak and all of a sudden the vacuum stuff doesn't work anymore. We are in the middle of an ice/snow storm here - temps in the teens tonight.

I spent some time, back when the weather was nice, tracking down vacuum related problems with the door locks, so I'm not unfamiliar with the vacuum system on these vehicles - it just seems odd that the vacuum stuff and the servo leaking at the same time are coincidental, but I can't figure out why the servo leaking coolant would have anything to do with the vacuum stuff.

ryan

rgnprof · #9 12-02-2006, 11:34 AM

OK, I've done some more TS and I can not get any of the vacuum hoses under the hood (driver's side by the brake booster) to hold vacuum (with Mityvac) - except for the hose leading to the reservoir in the trunk. Nothing else will hold a vacuum - the hose leading to the AC (green/yellow), door locks hose (yellow/brown), ignition hose - nothing!

I'm a little bit at a loss - I capped off the two vacuum connections that run to the underside of the servo and connected the hose together - no change! I've worked on this system before, so I'm not totally in the dark on how everything works, but...

Would a vacuum leak in the servo itself - where the 8, or so, black hoses connect at the top of the servo - cause this? I have traced these hoses back around to the passenger side firewall behind the battery and they look fine. I just don't understand the servo enough to know if it could my culprit, but I don't see anything noticeably amiss - all the hoses still look connected.

BTW, I have a good 22 inches of vacuum at idle from the pump...

Ryan

unkl300d · #10 12-02-2006, 11:51 PM

I feel your pain Ryan, unfortunately I don't know enough about the vac system to comment helpfully.
You seemd to have ruled out the vac pump. Make sure of this.

What about that thing that sits ontop if the injector pump. If that begins to fail, you can't shut the car off.

You ruled out vac lines behing battery. plugged servo feeds.

HMMM. What I don't know is whether one leak in one hose would cause no vac in many....

Good luck

D

rgnprof · #11 12-03-2006, 09:05 AM

I figured it out!

I drove the car around yesterday, numreous stops and after each stop I kept plugging lines until the car would shut off on its own. After plugging the line that runs to the door locks - car shut off with the key. Started reconnecting hoses one by one (except for the door lock one) and car continued to shut down appropriately. So I've isolated the problem to my vacuum door lock system - which I can fix (been there done that).

What threw me was the coincidental nature - I had the problem related to the Servo leaking, so I was convinced that the vacuum leak had something to do with the ACC.

I have had trouble shutting my driver's door - when I pull open the handle from the outside the handle won't spring back in position - kind of hangs up - and then the door is very difficult to close all the way. It will latch at the 'first level', so to speak, but I have to really slam it to get it to shut all the way. Is there some kind of spring in the door handle itself? Anyway, I am assuming that in my slamming of the door, I have knocked a hose off, or even broken one.

ryan

Moorewr · #12 12-03-2006, 12:30 PM

I had to replace little nylon bushing on door catch, you can very easily move it outward (toward door) and get a little easier close without breaking door seal. I bought the door catch from Mid Tenn Euro Cars at 1-800-548-4727, Jim has about 50 W123s plus lots of others he parts out from Manchester TN.
Ron
e-mail me for additional info about mid tn

Lostyankee · #13 12-03-2006, 01:07 PM

Narrow the vacuum search!
I assume you have working power brakes and the blower works.
Under the hood, left firewal, mark & disconnect (watch for breaking the blue/black check valves) all but the ignition vacuum switch line & plug with golf tees. Now try starting the engine & verify engine shut off with key.
If OK, move on to attaching the line to the climat control & servo goodies. Test.
If OK, move on to the door/trunk & maybe fuel hatch, line.
All that is left is lines to the reservour, trany and ALDA (at least in my 79 300SD).
I can't recall the color code but I believe the doors are green & yellow, heater is red and ignition black BUT please verify this as I have had a bit of eggnog! Do a search!

rgnprof · #14 12-03-2006, 01:47 PM

Ron,

My problem with the door seems to be with the door handle, NOT the catch. My door handle does not "snap" back into place after opening the door from the outside. It seems like some kind of return spring (?) is maybe missing??

ryan

Moorewr · #15 12-03-2006, 05:33 PM

Ryan there is a little spring in the guts of the door handle. My wife said door wouldn't close, so I went by the parts lot picked up a door handle, kept old lock (key) and put it in, didn't work so I looked at the catch and that was not letting the door lock close the door. So I ended up with both. Before buying the door lock, and Mid Tenn has lots, I would move the striker and see if it helps, look at the nylon inset. There are spacers behind the striker. Let me know what worked. I am learning so much and have been fooling with these things since 75.
Ron