82 300D new to me, runs great when cold, but when it gets hot the transmission seems to go out of gear, especially if i step on it in the higher gears.

It was a bit low on ATF, so i added some gradually, and hard to tell, but it may be slightly over full now. IN ANY CASE, ATF LEVEL MADE NO DIFFERENCE.

Usually if i let up on the diesel pedal, it will pop back in, sometimes rather abruptly.

I was thinking of changing the fluid and filter, but since it climbs right up my steep driveway when cold, i'm thinking that ain't it, as another 300D used to have to warm up forever until the tranny would kick in, and that one did benefit from a fluid and filter change.

Wondering if the tranny is shot, or some adjustment is needed.

Thanks!

Changing the fluid could help if the stuff that's in there has lost its viscosity. As the oil heats up it gets thinner. If the oil is spent it's possible that the viscosity is getting to the point that leakage in the pistons is high enough to cause shift problems.

Also worth checking your vacuum settings. Too much vacuum or a broken VCV will cause shifting problems as well.

__________________
Current stable:
1995 E320 157K (Nancy)
1983 500SL 125K (SLoL)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Gone and wanting to forget:
1985 524TD 167K (TotalDumpster™) [Definitely NOT a Benz]

Not sure how to measure the vacuum & tell if it is too much. I do have a Harbour Fright vacuum pump tho.

Where would i look for a VCV valve, & how can i tell if it is broken?

Thanx!

First things first :

Drain and refill both tranny _and_ the torque converter (it'll need a 5MM hex) plus the filter as Mercedes don't use the crappy open mesh screens like American cars do .

Do this before you go down the rabbit hole of vacuum valve adjusting .

__________________
-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

Just wondered if there was an easy way to check out that valve. The fluid seems pretty clean, and if this valve just needs a tweak, i could put off the fluid/filter job.

No idea where this VCV valve lives, or how i can tell if there is too much vacuum.

Thanks!

The deal is :

You have to approach things in the proper order else you'll not only wind up chasing your tail but you'll probably cause poor shifting by fiddling with the VCV before doing the basics .

Then of course, you'll blame the car instead of sloppy work .

__________________
-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

Changing the filter and fluid also allows you to look in the Pan and see if there is crap at the bottom.


Does jiggling the shift lever around produce any change?

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84 300D, 82 Volvo 244Gl Diesel

Good point about looking for crud in the pan.

The shift lever seems pretty solid.

Is there anything else i should look at under there while the pan is off?

Thanks again!

Sure, look for anything other than fluid. If you find something else just collect it the best you can, photograph it and post it here. The pros here are priceless when it comes to evaluating problems.

__________________
84 300SD
85 380SE
83 528e
95 318ic

If there's any visible crud in the tranny's pan, the filter will be sufficiently clogged to cause reduced fluid fluw internally causing just the initial complaint .

The need to always do the basics first never changes because the laws of physics never change .

__________________
-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

SOLUTION (in my experience)

I had the exact same problem on all 3 of my w123 300d's to some extent.
.

And EVERY SINGLE ONE WAS FIXED with a simple ATF drain and refill, replace the filter and gasket as well of course.

AND IF YOU DONT WANT THIS TO HAPPEN AGAIN, use a German ATF, a correct fluid can be bought here at pelican parts. It will cost a little more but I say its necessary.

No one changes their ATF enough, if at all. It needs to happen Everytime you buy a new Benz or every 50k or so.


If it was a vacuum, vcv, or modulator issue he wouldn't only be experiencing these problems at FOT, it would be noticeable much sooner if he had a slow vacuum leak in his system somewhere. But don't get me wrong, u do need to go thru all the steps to make sure Ur getting best performance and making sure no future problems will happens

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Thank you .

I am always amazed at folks who ask for help then ignore it .

There's a reason some here can drag a junker out of someone's back yard and get twenty years of good service out of it inexpensively .

If you don't want to spend any effort on routine maintenance, buy Japanese ~ they're GREAT cars just soulless appliances .

__________________
-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

Finally got around to the fluid & filter change. Pan and torque converter.

There was a thin layer of greasy crud in a small corner of the pan, and some crumbs of what seemed to be carbon. The fluid was red with a little brownishness and had a very slight burnt smell. The gasket was so old it cracked when i removed it. A few very tiny metallic looking particles.

Runs much better now, tho once or twice it did race a bit before settling into the next gear. (Is this what is meant by "flaring"?)

Any thoughts as to what if anything else should be done vis a vis the tranny.

Car has 194 K miles on the odometer.

does it flare/race more or less (or the same) as the trans warms up?

__________________
Andrew
Montclair, NJ
--------------
1982 300D Turbo
120k
Petrol Blue Green

Glad to hear it helped .

An experienced member here suggested I try "Trans-X" additive in my '82 240D's ailing tranny, I went to Autozone and discovered seven (IIRC) different Trans-X products, read all the labels and grabbed the yellow bottle one as a 'Hail Mary" and it helped to firm up the shifts and staunched the irritating slow dripping for over a tear .

I was very impressed with the product and hope he'll chime in here to specify which of their products is best for Mercedes trannies .

__________________
-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better