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Transmission issue and oil change - given conflicting advice, help!

4K views 10 replies 9 participants last post by  Markcreative 
#1 ·
Hi, I have owned my 1998 R170 for about a year, only 73,000 miles on it still and has run beatifully, it's in very good condition and has flown through the past two MOTs without even an advisory.

Starting to get less smooth gear changes though, it's not hugely noticeable but I notice it. Have been told the following:

Get the tranny oil changed, it seems to be popular on this forum and an independent has recommended it. Two auto box specialists have strongly recommended against it, saying it flushes contaminants around the gearbox that had settled, and when they have done it, it sometimes creates problems.

Have also been told it could need a software update for the box, once cars have done a few miles a software update can account for the wear and tear and tighten everything up, have been told by a MB technician this is rubbish as it is 5 speed fully electronic box and it auto adjusts.

Have also been told to just reset the tranny instead of update it.

Have also been told it could be sensor failure in the box that tells the car the internal speed of the tranny so it can adjust for smoother changes.

I am getting so much conflicting advice I am reluctant to do anything at the moment as I will be most likely just wasting my money.

Any advice would be gratefully recieved.

Cheers

Mark
 
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#2 ·
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#3 ·
I changed my fluid and filter around 62,000. Made a big difference to the smooth operation of the box. I also changed the pilot bush which was leaking and allowing fluid to wick up the connector and wires. I think mine may have been a little low on fluid because of this. A pretty straight forward job if you are handy with the spanners and don't mind working on your back.
 
#5 ·
I did mine a couple of years ago and it made a big difference in shifting. While i had the pan down i changed the filter and put a strong magnet the size of a quarter in the pan to catch anything that might be floating around. One year later i changed it again just because and noticed the magnet was frre of any metal bits. :). its worth the money and time to do the job.
 
#6 ·
I changed mine at 110-115k as far as I remember. I had a famous leaking connector issue. The oil leaked to the harness and I got shaking car when in reverse =(
Drained the fluid, changed filter and connector, gasket and performed flush. Disconnected the battery overnight and it reset the transmission memory. There's other way to reset the tranny memory. Seen it somewhere on this forum. Drove in under 3000 rpm range (40 shifts or so) for a while so it can learn my driving behavior. Yes, I'm not a racer (most of the times) :burnout:
Now it runs perfectly smooth! Oh, forgot to tell you, changed all three mounts recently and now even don't notice how it shifts =):rb
Since yours is pre-facelift you probably don't have a magnet inside of the drain pan. Magnet part # is 220 271 00 98
You will also have a plug for the torque converter so you won't have to perform flush. Just position the torque converter so you can access the drain plug and unscrew it to get the rest of the tranny fluid out.
 
#8 ·
Your '98 will have a drain plug for both the torque converter and the pan, so you can drain all of the old fluid out and not have to worry about doing a power flush. Cars after '99 did not have a torque converter drain, so you could only drain about 50% or less of the fluid in those. Change the ATF along with the filter and gasket and check for leaks at the electrical plug too. Use the proper fluid.
 
#9 ·
Like Leapyfish said, Mercedes has gone a little schizo on Transmission fluid changes. For a while there they talked about "lifetime" fluids that did not require changing. I even had the local Service Advisor tell me that two years ago, that after a change at 60,000 miles I'd never have to change it again. Now I have read that the recommendation is every 40,000 miles or so. Take your pick - either they want more of your money or it's helpful for the tranny. Based upon the critical nature of the part I'm willing to fork over the $400 every two years or so.
 
#10 ·
AFAIK Mercedes' stance on the transmissions that came out as "filled for life" is still that they are filled for life. They did not change that recommendation even though the transmissions in the newer cars were identical and required one service at 39,000 miles. However, how many fluids in a car are actually lifetime? None IMO. That's why I service mine every 50,000 miles on the car that gets daily use and I'll probably do the SLK at 30,000 miles which ends up being about ten years.
 
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