I would like to think I'm on top of my vehicle maintenance all the time, ever ready to check my fluids, dot my i's and cross my t's, spending as much time looking at parts as I do driving. But there is just one thing that has slipped past me for reasons unknown, and is probably the most critical of things to not let slip by weekend after weekend. And that's the transmission fluid/filter! Since I have had my car (one year last month) I have not changed out my tranny fluid, and who knows how long ago the po did it.

I never thought about it until I drove a friend of mine's diesel Mercedes last weekend. I marveled at how smooth the shifting was, and wait, there's another gear to shift through?! My stomach dropped once I realized that for God knows how long my car has not shifted anywhere NEAR proper: Leaving it in Drive it shifts once at 17 MPH, again at 23 MPH, and that's it! Then when winding back down it shifts down with a clunk at about 20 MPH, meaning it skipped through a gear or two? Oh man!

So I think every single time I go from a stop it skips a gear, then whenever it shifts back down it skips one or two gears. Hooraay! I am definitely changing out the fluid this Friday, but my question now is, does allowing it to drain by itself get ALL the old fluid out or should I spend the $100 taking it to a shop for a quick flush, removing 100 per cent of the fluid? And if I'm better off taking it in should I at least replace the filter before bringing it in? (obviously lots of fluid will drain out, I planned on putting fresh fluid back in just to drive it to the local shop.)

Let me know what your take is on this. Hopefully after forking out the money for a tranny rebuild I will learn.

Thanks for letting me vent!

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1981 300SD, odometer stopped at 188,000

Those are normal shift points when accelerating slowly, your vacuum/bowden cable adjustments might not be tuned properly.

What are your RPM's at 55 and 75mph? If its going about 3400-3500 at 75mph then its going through all the gears just fine, and its in 4th at that point.

Fluid can be fully drained by removing the plug on the torque converter and on the pan, then remove the pan, change the filter, and put the pan back on with a new gasket.

For fluid I recommend Valvoline Dexron VI Synthetic, its available at NAPA for like $4.50 a qt.

To get to the torque converter plug, you have to rotate the engine CLOCKWISE slowly while watching the little hole on the bottom of the front of the trans, when it comes into view, you'll be able to loosen it with a allen key. Full fill of the trans when you've drained all fluid is about 7.2qts or so.

Hope this helps!

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-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

My tach bounces back and forth a lot. From time to time it will hold steady at 55mph, at about 2500 RPM. Are you saying that at the 55mph point it should be in third gear and shifts once more by the 75mph point or it should already be in 4th by 55mph? Because that shift at about 23mph is the last one it does. Now if mine is working normally then my friend's is way out of whack and I need to tell her!

A few weeks ago I messed with the bowden cable and did not notice any difference in shift. I read one time that turning it 1/4 or 1/2 either way will show a difference- I ended up turning it full revolutions after nothing going 1/4 or 1/2 way around, both ways, still without any difference.

I'll follow the procedure indicated on dieselgiant.com for getting the pan off and replacing the filter, and the TC plug is under the pan which gets removed or is it placed further forward on the tranny? I have yet to give this area a close look, I'll understand better once I get under there..

Also for clarification, I should turn the bolt on the power steering to rotate the engine (as if I were adjusting the valves) little bit by little bit, checking until the hole has come into view? And I don't have many allen wrenches, would a good set of allen keys have the size needed in there?

Thank you much for the advice!
-Geoff

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1981 300SD, odometer stopped at 188,000

Yes allen keys will suffice for removing the drain plugs, I believe the proper size is 5mm or 5.5....not sure, just use the size that fits most snug.

As for turning the engine, it does work to turn the power steering pump bolt/pulley, but if the belts aren't tight they may just slip. Best way is with a socket on the crank pulley bolt. 1 and 1/16 deep socket works well. Always be sure to turn it clockwise only, if you are standing in front of the engine it should be clockwise. Turning it little by little and checking the torque converter hole is correct. The torque converter is at the front of the trans, right in front of the front of the pan. You'll see an area that looks like a grate with a larger hole in it, thats where the torque converter drain plug will line up. Inside the pan all you will find is the filter. Be sure to not over tighten the bolts holding on the pan, and tighten them in increments opposite each other (like you would do with wheel lugs), hand snug is all they need to be, not real tight.

2500rpm at 55mph would indicate that it is in 4th gear, so you're probably just fine. If it was still in third at 55mph you'd be up around 3600rpm! And it'd be very loud. Not to mention the car would top out around 74mph....with the engine revved up super high.

__________________
-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

I wouldn't do the flush without the filter and I would do them at the same time. All you're doing is running the dirty fluid thru a dirty filter. If you insist on the flush, do it, drop the pan, replace the filter then refill. Replacing the filter then going to get it flushed is a waste of a new filter.

Also, it took a good 8-9 turns of my bowden cable to get things right. My car was in 2nd gear at 5mph and in 4th gear by 35mph max with my foot to the floor. It also wouldn't kick down.

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Sharing my partner's 2012 Forte 5dr SX til I find my next 123 or 126..
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Do I miss being a service advisor ???

Second that you probably have a bowden adjustment problem-
I had the problem you're mentioning, and it turns out I needed to do a LOT of turning of the Bowden before it shifted normally.
What's probably going on is that you're not feeling the 1-2 shift, as it's so early.

Thanks for the description pawoSD, I can picture what it is I need to do. I don't know what I would do without this forum... I'd be even more broke than I am now from taking it in upon every worry.

I'm going out to mess with my bowden cable right now.

Thanks again all!

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1981 300SD, odometer stopped at 188,000