Splipping Transmission - PeachParts Mercedes-Benz Forum

Tom Garrison · #1 10-20-2006, 12:30 AM

I own a 1993 300e with 204,000 miles. About a 1,000 miles ago the transmission began to slip between first and second and second and third when the car was cold and first warming up. My mechanic originally suspected it was time to rebuild the transmission, however, when he opened the transmission up he said everything looked fine. He was unsure what the problem was but made an "adjustment" which cost only $70 compared to the roughly $2,500 I was planning to spend on the rebuild. The car does shift differently, I think perhaps a little harsher. The symptom of slipping, however, remains. Before taking my car back for round two I thought perhaps someone on the forum might have an idea of what the problem is from which I might provide some useful information to my mechanic. Any thoughts?

dpetryk · #2 10-20-2006, 08:01 AM

You cant really tell the condition of the friction components of the transmission unless you disassemble it. Its the friction components that wear out and you cant see them by simply removing the pan. With that many miles I'm sure you need it rebuilt.

gmercoleza · #3 10-20-2006, 09:23 AM

You might want to double check with the mechanic, but it sounds like he may have just firmed the shifts up via a turn or two of the modulator. This is only a bandaid. As mentioned, friction materials eventually wear out. The cylinders can also start to leak, causing them to weaken in their function. Also, the valve body can get varnished and plugged by old coagulated sludge; you would never see this without disassembly. I speak from experience, having had to disassemble and clean mine out on the 300E a year and a half ago. Those tiny check balls can eventually bind.

Matters are worsened when the trans fluid is not changed religiously every 30K. Excluding maintenance history, given the mileage on your tranny I'd say it's quite possible you just need to break down and get a rebuild done.

david s poole · #4 10-20-2006, 12:18 PM

agree with prev post.the large centre clutches for reverse will be all the way down to the metal.all your guy did was to tighten the modulator pressure to cover the problem.you need complete o/haul.

bpaz_ph · #5 10-20-2006, 12:30 PM

Hi guys,

I have often read "transmission slip" in the forum. What is it? Just want to know in case it happens to my car.

gmercoleza, how hard is it to DIY the tranny? I have an 87 190e 8V and read that the clutch bands on these cars eventually wear out.

Thanks in advance.

gmercoleza · #6 10-20-2006, 12:42 PM

I've never done the bands, only the valve body. Sorry, can't comment - maybe one of the experts here can.

dpetryk · #7 10-21-2006, 08:39 AM

Transmission slip is really the same thing as clutch slip with a standard transmission. Have you ever experienced that? You know - the clutch is fully engaged and it slips when you try to accelerate too hard. It simply cant hold the torgue. Why ? because the friction surfaces have worn down to the point that they no longer hold. Same thing in a slush box.

gmercoleza · #8 10-21-2006, 08:55 AM

Also, sometimes a manual clutch slips due to a tired spring - worn or leaking pistons or seals can cause the same thing in an auto tranny.

bpaz_ph · #9 10-21-2006, 10:10 AM

I'm totally naive about automatic transmission since this is my first one. Also this is the first car I have owned that's more than 15yrs old when I got it.

The only time I experienced clutch slip on a manual manifested as a vibration on the pedal when I was releasing it.

Is it the same way on an AT?