My new (to me) 1985 300sd has 265k.Runs well.I am going to adjust the valves this weekend.How many miles are the automatic transmissions good for? The fluid is nice and red and does not smell burnt.Shifts a little hard sometimes so I'll problably change the vaccum valve.Are there any other adjustments or tips to keep her running as long as the motor?Thanks,,, Joe

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auto box good for life of car but has an oil filter insde changing oil and filter can make a big difference
to do the job u drain and remove gearbox pan, filter held in by 3 screws u have to drain torque converter also.turn flywheel till drain plug comes
into space in bellhousing.dont over fill holds about 5.5lts when oil added start up and move through gears take final reading from dip stick when hot

 

Look in the maintenance section of www.dieselgiant.com for a pictorial of what the true homey above me is talking about. I really like that site's pictorials.

 

Yes, dieselgiant.com is GREAT. They have great tutorials. Did you make sure your transmission is not leaking, if so get it FIXED RIGHT AWAY.

Also, if you know the history of the car, you should do a few other things (if you want to baby the car and have it for many years).

1. Valve adjustment - big difference (see dieselgiant as well) I couldn't do it myself on my 84 300SD, so I had an old guy at the Mercedes of Fairfield, CT do it, who has been working there over 20 years and knows diesels. It was a little expensive, but well worth it.

2. If the car has never had the fuel tank filter replaced, do it.

3. Check the fuel lines, mine needed changing at a little over 100,000 miles (more as a preventative maintenance than anything else).

There is a whole list of things you can do, but it depends on your budget and if you are a fanatic like I am about MB diesels.

 

with regard tothe transmissionvacuum modulatorthat sits on top of the shut off valve behind the injection pump...it can be adjusted... remove it and you will see an adjustment screw on the back...do so by backing it off a few turns and then try the car...no need to change it if an adjustment is all it needs. I did mine and my hardshifting was back to smooth. You may have other problems as well....there is also a vacuum valve on top of the valve cover anda modulator on right side oftrans its self. Linkage adjustment may be required alsobut if you are not sure how to do that stay away fromthem.Make sure all your vacuum line are in good shape...these are vacuum cars and any vacuum leak can and will affect your car's preformance. If the engine is running ruff....clean your alda...Dieselgiant.com has a thing on that as well

 

Hey It's Scott again.

In regards to the transimssion modulator that is located behind the injector pump and then making an adjustment. Can you clarify this point.

To the original poster: I had the exact same car. Blue, 1983 300SD. The transmission started to shift hard on me. Problem continue to get worse. I took to a mechanic (few times that I had) and they way overfilled the trans. Drove two weeks with same hard shifting getting worse.

I replaced a modulator thing located on the transmission like under where the shifter is in the car. This did not help. Car kept sticking in gear and wouldn't go into 2d and 3rd. Finally took took to Trans guy.
One thing that helped temporarily was that he removed the "kick down" switch that is located behind the gas pedal.

This could also be your problem. The kickdown switch tells the trans to shift into a lower gear. You can just unplug it.

Anyway, I still would like to hear more if there is another modulator that I was not aware of.

Lastly, That car currently sits. If you neeed spare parts...

I may end up putting the engine into a 1979 300SD that I am working on with a bad piston. Problem is that the 1983 engine as I recall drip a bit of oil and I hate oil drips on the ground.

Scott

 

Scott.

The trans vacuum valve sits on the shut off valve...(earlier cars did not have them. My 78 300Dfor example has no vacuum to the trans at all. it has only a mecanical but adjustablemodulator on the trans which is avery difficult one to findand if they leak it will affect the trans in time. I cant find it anywhere.) thats one one you have to remove if you need to replace your shut valve....It is held in place by 2 screws....easy to remove....on the back of it is an adjustment screw...turn it a few clicks counter clockwise.....until you get the best result...just turn the screw a little at a time thought..no big changes. trial and error...the one on the valve cover gets gunked up, just clean it if it isnt cracked.the one on the trans its self is adjustable on some cars as well...depends on the model. Start with the one on shut off valve first. remember that these early trans were not americam power glides in the first place...they always did shift a little funky...that is were accelererator let off at the right RPMhelps ...sorta like an auto manual trans.....rpm is everything and one needs to learn how to make ones car shift smoother with pedal action.... also trans service is critcal...those are paper filters on old transmission and they will get clogged resulting in pressure loses and erratic shifting as well. please also note, the the B2 valve can be a problem...they ususally just fail or leak...Dieselgiant.com has a thing on that. but the B2 valve with usually only cause a no go in first. They have been known to fail and cause shifting problems as well. and last Vacuum vacuum vacuum...over the years these cars have had their vacuum stuff changed moved around and stuff removed...there were restrictors instaled that have over time either be clogged or simply removed and while this wont stop a car it will affect its performance...check valves in the wrong place and failed one will create probs as well...these are made of plastic and will fail in time as all things do. You might want to call me as a phone call is worth a thousand posts


email me your numberat b747200skipper@aol.com and i will give you a call if you wish