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Old MB diesels suck!!!

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Banjo

Banjo

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...Or don't suck, in the case of the one in my service bay right now.
Symptom... Car won't shut off/ has delay shutting off and the automatic door locks don't work. Also the HVAC unit dosent change modes very well.
Hey Doc! wanna call this one?
Any of you who've ever delved into a classic 80 Mercedes, knows all these systems are vacuume operated.
Evidence of engine oil in the lines tells me the vacuume pump seal is going bad. all rubber hoses are swollen, I've already replaced 2 leaky door lock actuators, and the iggy vacuume switch.. and it's still acting up!!!!
It acts like the new switch I put on the iggy, leaks as bad as the old one......
I will win the war!!! but so far it's kickin my butt!
It's kinda fun to get to understand how all the systems work. pretty clever really.
I'm trying to convince the guy that I'll pay his reapir bill if he'll just sign over the title! hehehehe.
grin.gif

the next battle starts on Monday....
 
Got smAllData? A diagram of the vacuum routing is a must. The seal has to be the first order of business or you'll be chasin' your tail forever. The iggy switch is likely to be fine, the little fuel cut-off switch just isn't getting vacuum.... brown tube, IIRC. REPLACE all the rubber ho$e$, all those goofy junctions. There are some buried under carpets, too. The flap motors on the heater box CAN be R&R'd without removing the unit but ya gotta be a spider monkey to do it. Some of the bits on those actuators can be "modified" to work. The original design actuators are hen's teeth, the newer ones will accept hardware from the old ones to make 'em work. Gotta be inventive here: Think MacGyver. :wink:

Your best friend here will be an EXPERIENCED Benz parts guy.
 
I had an '84 Audi 5000 at one time. It was a very good car until the vacuum system started fouling up. Most German cars of that era used vacuum to power accessories. My vacuum accumulator failed, a friend of mine who is a very experienced MB/Porsche/Audi/VW mechanic warned me to get rid of the car. He told me that the next thing to go would be the vacuum pump. The only replacement pumps were all putting out 2 psi more than the original pumps. That extra psi would be no big deal to all new vacuum lines but my old lines would npt take it. Then there would be @ $1200 in parts to replace all the lines and junctions.

Be ready for the computers for the HVAC to be situated in odd places too. In the Audi there were three, all in different areas of the car.

Vacuum operated door locks, sun roof, gas cap door lock, windows, HVAC movements, even the braking system was tied into it. Nightmarish when they get old and begin to fail.
 
I've had a couple of sessions with this ol' gal now. a hand operated vacuume pump is a necesstiy. I know where all the junctions under the carpet are, I know that the door lock system is now holding vacuume in both the lock, and unlock positions, and I've tested the vacuume reservoir and it's feed line.
the HVAC, door locks, and iggy al tie into a 3 way "T" on a line that comes off the brake booster. If I unplug any of those pipes at the 3 way, I feel hardly any vacuume at the unplugged port. If I unplug both the HVAC and iggy, the vacuume will slowly charge with the door locks and reservoir., and if I unplug all 3 and hold my fingers over the holes, I Get decent vacuume.
Needs a bit more testing, but that tells me I still have issues in the HVAC and iggy circuits.
truthfully, I like this kinda stuff. Usually I don't get owners willing to spend the $$$ to have me take time to look at it.
 
Diaphragm tears in the HVAC actuators. If you block off the HVAC circuit and have the shut-off gizz connected it should at least shut down properly.

I've replaced all but the center vent/defrost actuator on Diesela. A real challenge with the "box" in place!

The others all had diaphragms which were age deteriorated to the point of crumbling in my hand. That middle one is certainly the same. As long as it blows cold air Herself keeps driving... I can't "cripple" the thing for vent flaps. It'd be a two day deal and Her wouldn't stand for it.
 
Boy this post makes me happy I don't own my benz anymore, I loved the car, but not the vacuum lines, nor the fuel distributing octopuss that lived on top of my engine.
 
I have found a couple of cars over the years where the fuel door "lock" was bad.... An easy one to miss. Try to get (Borrow as they are $$$ to buy) a "smoke machine" like for testing fuel tank evap. systems. Plug that in, and it will cut down the search time.
 
That was the first thing I blocked off/disabled, Jesse. The durn'd things have led me on some lengthy journeys in past. One client had a "gray market" 2-door coupe with a Chevy V-8 shoved into it... I ~did~ get the A/C sorted eventually. It had the old Chrysler control unit in dash. What a Frankenstein THAT thing was. In the end after I'd got it all working the guy was crabbing over the bill! We told him to take it to a Chevy dealer next time. Just don't bring it to US anymore.
 
Fuel door is OK. It's easy to get to in this wagon, and like I said, I know the door locks are fine now.
I found the Iggy switch with the smoke machine. It only leaked smoke with the iggy in the "on" position.I almost missed it. I havent seen any smoke from any of the HVAC parts yet, but it also never smoked out of the door lock actuators that tested bad with the hand operated pump. (and yes I did bypass the one-way valves)
The only problem with the smoke method is that you're testing the components under a slight pressure as opposed to vacuume.And As I'm finding, they may leak one way but not the other....
jeesh Doc.. I don't know how long I've looked at your signature and never caught on that you've made the grills outta keyboard strokes.... I just thought it was HTML that dident get translated into smilies.... Some of us are a bit slow....

BMW OO=00=OO

Jeep O||||O

hehehehe that's fun
 
*sheesh*

Sometimes I worry about ya, boy. :jester:


...it's called "ASCII Art" BTW. :wink:
 
Start worrying then..... I live in my own little world.
Economic crunch coming on. art may be in my future supplimental revenue plans.
I might try some hand painted signs, and the like... There's some other far fetched options too. Childrens books, and comics...
I don't do "normal"
 
I ain't done "normal" from birth.

Ship me yer email addy in a PM.

"There's a change about to fall"....
 
So Doc, When were ya gonna tell me that the vacuume switch on the iggy is DIRECTIONAL?!
It only has 2 ports, so I figured it diden't matter which way the lines were hooked up. it's just an on off switch.
NOT!!!!
the side that goes to the engine shut-off valve (controlled side) is vented to atmosphere when the switch is closed (iggy on) to release any vacuume that may still be holding the valve. If you hook that up backwards, you effectivly vent the entire vacuume system while the ignition is on.
All 3 door lock modules were leaking in the unlock position. the little boot around the plunger rod was dryrotten and cracked on all 3. so those replaced,iggy switch hooked up the right way, and all is well.
See Dale. We all run into/ create problems that have us stumped for a while.
I'm ready to take on the next "slug" that comes in now!!!!
 
aeronca65t said:
Banjo said:
Old MB diesels suck!!!
Click to expand...

Actually, the turbos on them <span style="text-decoration: underline">blow</span>! :jester:

yuck-yuck-yuck-yuck....I <span style="font-style: italic">kill</span> myself. :laugh:
Click to expand...
Who asked you?! :devilgrin: hahahaha!
Now I probably woulda said it that way if I was workin on the turbo, but since it's the vacuume circuit.......
Technically, this car's problem was that it diden't suck.
Wait a minute!!! whay am I explainin myself here?!?!?!?!
Go race your Escort!!!!! :jester:
 
Benny said:
So Doc, When were ya gonna tell me that the vacuume switch on the iggy is DIRECTIONAL?!
Click to expand...

My bad.

but I ~DID~ say it was th' BROWN tube.

Apply vacuum to the switch and th' beast should stop like it hit a wall.
 
Doc

"Support bacteria. They're the only culture some people have."

did yee bang da noggin again.

Lol
Pat
 
I opened this thread because I thought you were discussing "Old" MB diesels. Then the first thing I read is that it's from '80.
Why didn't you post that you were working on a middle aged Mercedes?
My '59 diesel always works just fine. Of course it doesn't have a single vacuum line in it.
 
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