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  #1  
Old 01-14-2007, 11:45 AM
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1985 300 turbo diesel

I just bought my first mercedes benz. It is a 1985 300 turbo diesel in what appears to be very good condition, though there are a few things that need to be fixed and I need help to fix them correctly. I have been reading in this forum since yesterday and you all seem very helpful. I am excited and proud to own this vehicle so the first thing I need is a repair manual to familiarize myself with it. I live in California's central coast area, Aptos to be precise, and anyone who lives nearby would be welcomed to share info.
I am not a mechanic but have mechanic ability, though I have never work on a mecedes benz. My father owned a couple years ago and I have always been impressed with german engineering.
It seems so far that the 2 center vents are not working. The front defogger works as do the side vents and the fan works but as I said I do not know much about these cars other than what I have read here which says that there may be a vacuum leak. The wood strips on the glove box are coming off and need to be glued back on. The car is an automatic and runs very well. No noticable damage although the title is salvaged from a rear end accident years ago. Repairs to the bumper were done by qualified mecedes benz shop in Monterey Ca. and look perfect. The car was owned by a friends father who passed away 2 years ago. Since then it has been garaged and driven only occasionally.
How often does the oil need to be cahnged and what grade should be used. Any and all info on how to properly care for this automobile would be greatly appreciated.

Thanks !
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  #2  
Old 01-14-2007, 12:27 PM
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Search on oil, and you'll find a lot of heated discussion. At a minimum, use diesel rated oil
I glued on my wood trip with 5 minute epoxy (gel I think)
Center vents could be switchover valve or pod located behind the dash, accessible, barely, via the glovebox. I blocked off the vacuum line to the pod, put a piece of aluminum flat stock in the vent to hold the flap open, and now control them by turning the manual vent control at the outlet. Some people have replaced the pod without removing the dash. It's not easy.
Buy a Mity Vac. Harbor Freight Tools is a cheap source.
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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13
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  #3  
Old 01-14-2007, 02:55 PM
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Congrates on the new to you car? Watch out the obsession is just starting.

The vent is most likely a vacuum leak. You will need a Mity Vac, or some other brand vacuum hand pump with a gauge. Something along THESE LINES. You can test the center vent actuating pod by removing the glovebox. The actuator is directly behind the two center vents, and it's pink so you can't miss it. It's a very tight space, but you should atleast be able to test it. If the actuator won't move or hold vacuum when you pump your new vac hand pump it's needs to be replaced. As long as the plastic isn't cracked you can just replace the rubber diaphragm that is inside. You can get replacement diaphragms from Autoluxmbz.com. The diaphragms are much cheaper than buying a whole new pod. I was able to buy more than enough diaphragms to fix all my pods for teh same price as one new pod. Good luck, and don't be affraid to ask lots of questions, we've all gone through it too.
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  #4  
Old 01-14-2007, 05:02 PM
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1985 300 turbo diesel

I took the auto out this morning and it is having trouble shifting. Automatic transmission and it takes heavy acceleration, high rpm's to shift into second... and the same to shift into drive. I am thinking that there may be a vacuum problem or the accuator may be faulty. Can anyone give me some advice... and remember this is my first mercedes and second day I've had it.

Thanks !
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  #5  
Old 01-14-2007, 05:17 PM
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Quote:
Originally Posted by whynot2 View Post
I took the auto out this morning and it is having trouble shifting. Automatic transmission and it takes heavy acceleration, high rpm's to shift into second... and the same to shift into drive. I am thinking that there may be a vacuum problem or the accuator may be faulty. Can anyone give me some advice... and remember this is my first mercedes and second day I've had it.

Thanks !
Look down below the accelerator pedal.

You'll see a button switch under the pedal.

Find the wires to the switch and unplug the switch.

Drive the vehicle again and report back with results.
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  #6  
Old 01-14-2007, 05:56 PM
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Welcome!
It does appear you have some vacuum issues, as the transmission shifting is vacuum aided.
One thing about your center vents, I believe they only are designed to function on air conditioning only, when the 3rd button from the right is pressed. They do not function with heat settings I don't think.....
There are soooo many posts you can find via the search function for your vacuum issues. Very very common......
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Gone:
'95 E300 188K "Batmobile" Texas Unfriendly Black
'85 300TD 235K "The Wagon" Texas Friendly White
'80 240D 154K "China" Scar engine installed
'81 300TD 240K "Smash"
'80 240D 230K "The Squash"
'81 240D 293K"Scar" Rear ended harder than Elton John
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  #7  
Old 01-14-2007, 05:59 PM
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Quote:
Originally Posted by whynot2 View Post
I took the auto out this morning and it is having trouble shifting. Automatic transmission and it takes heavy acceleration, high rpm's to shift into second... and the same to shift into drive. I am thinking that there may be a vacuum problem or the accuator may be faulty. Can anyone give me some advice... and remember this is my first mercedes and second day I've had it.
Thanks !
Or, In the other direction.... perhaps you have a build up of varnish in the little holes in your auto trans shifting body. Your trans mechanisms are directed by outside things like levers and vacuum.... but inside the actions are hydraulic controlled. If the holes are blocked at all it will make a difference in the speed the actions take place ...like the clamping of the shifting clutches.... which is about the same as you slipping a manual clutch....
If you do a search about ' Trans-x' in the archives..... use my name as poster...
there is lots of good information...
MB suggests changing the fluid and filter in our cars way more often than old American cars required... which may accounty for some of the problems we read about.
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  #8  
Old 01-14-2007, 06:01 PM
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wires pulled at button

Brian --

I pulled the wires at the button under the accelerato and drove again. The shifting worked... what does this mean ?

Thanks!
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  #9  
Old 01-14-2007, 06:04 PM
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Originally Posted by whynot2 View Post
Brian --

I pulled the wires at the button under the accelerato and drove again. The shifting worked... what does this mean ?

Thanks!
That switch is the "kickdown switch". When depressed, the transmission is signaled to drop to a lower gear. When stuck (as yours is), it won't let the transmission upshift until it gets to very high rpm's.

Replace the switch (you can buy it right on this site.......press "buy parts" on the top of the page) and the problem will be permanently eliminated.
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  #10  
Old 01-14-2007, 06:22 PM
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kickdown switch

Thanks Brian --
I just ordered the switch. Is it bad to drive the car with the wires disconnected? Should I wait until I replace the switch?
I am extremely thankful for your help and very happy to have this forum to turn to.

Tony
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  #11  
Old 01-14-2007, 06:37 PM
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Quote:
Originally Posted by whynot2 View Post
Thanks Brian --
I just ordered the switch. Is it bad to drive the car with the wires disconnected? Should I wait until I replace the switch?
I am extremely thankful for your help and very happy to have this forum to turn to.

Tony
No problem driving without the switch. The only issue is that you won't get a transmission kickdown when you floor it. If you need a kickdown, just use the shifter and shift it manually.

Anytime. Help is what we do here.
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  #12  
Old 01-14-2007, 07:20 PM
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Glad you found your issue! You may still want to heed the advise of the Trans-X in the future. It really helped me with my '80 wagon.....
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'05 Acura TL 6MT
2001 ML430 My Spare

Gone:
'95 E300 188K "Batmobile" Texas Unfriendly Black
'85 300TD 235K "The Wagon" Texas Friendly White
'80 240D 154K "China" Scar engine installed
'81 300TD 240K "Smash"
'80 240D 230K "The Squash"
'81 240D 293K"Scar" Rear ended harder than Elton John
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