Flushing transmission, new fluid leads to slippage: myth or reality? - Page 2 - PeachParts Mercedes-Benz Forum

porkface · #16 06-17-2025, 05:45 PM

if you call them, they might be able to tell you the mileage. then you decide whether it's worth a look if there is a trans and price it out.

agillot1947@gmail.com · #17 06-17-2025, 06:13 PM

Quote:

Originally Posted by cmac2012

Like a moron I did some damage to my SDL tranny by running it with too much fluid. One day it would not do anything except in first and reverse. I have kicked myself for it many times. For a while I thought I had ruined it. But then after a year of sitting it I miraculously found it was working pretty well.

By then I had corrected the fluid level, I took it out on the freeway to see if it would slip - it never did. So I've been driving it more. A few days ago at a stoplight it would not move in drive. I put it down to low and took off - when I shifted up it behaved normally.

I checked the fluid while warm, it was a tad bit high, I siphoned off maybe 6 fluid ounces. It then read right at the add mark so I put some back in. I noticed it was not bright red. It was brownish red, which only makes sense.

I'm thinking new fluid and filter would be a good idea, but then I started First reading that I might be disappointed. It will be a while before I buy a rebuilt tranny.

Any opinions?

First you dont flush . you remove the pan , change the filter [ important ] / pan gasket , you drain the converter , you put 3 quarts in , start car , add another 3 , check level , you may need another 1/2 quart .

cmac2012 · #18 06-20-2025, 05:05 AM

Thanks for that. I spent so many years with my 5 speed E30 cars I am not real experienced at maintaining auto trannies.

I'm sure some people might think it a bit foolish to try to keep this old thing going. Something about it, just feels like class, luxury, performance in one. The new used engine I had put in is incredibly good.

I read some years back that the 300SDL is considered by many to have been the golden age of Mercedes diesel.

There have subsequent engines with more hp, but you can't even get the latest diesel model in the US, I think I have that right, the S class with a really happening engine. But it's a complicated engine methinks. The OM603 might be almost as durable as the 617 but more powerful, in stock form anyway. I like the looks of my car, the front end feels really sweet, I really like the leg room in the backseat. I've done some big group trips and sitting in the backseat on the passenger side is ideal for watching the instrument panel. The legroom is just incredible, especially for a car that gets 25mpg.

Here I am at a hippie fair in North Central Washington. I woke up after my first night and someone had put this doll on my roof rack, sort of tied in place. I still have it.

Sugar Bear · #19 06-20-2025, 09:51 AM

IMHO, it may be best to either one, do nothing other than add Lubegard or two replace only the filter in case the old one is restricting oil flow, catch and reuse the old fluid and still add Lubegard. The problem with new fluid is that if the clutches are on the razor edge of failing the new fluid will hasten that and putting the old fluid back won't reverse it.

Just curious is there any delay in the reverse gear engagement?

In the interim explore your best options for rebuilding the existing transmission (Sun Valley) or finding a good used one.

cmac2012 · #20 06-24-2025, 08:07 PM

No, haven't noticed any delay going into reverse. It seems now and then there's a funny hiccup, but nothing that lasts long enough to look like an identifiable problem.

Sugar Bear · #21 06-24-2025, 10:07 PM

Put back old filter - no.

Put back old fluid? You could but it probably wouldn't help a lot. In addition to removing fluid with particles in suspension, the new fluid will clean the clutches some and you won't return material to the clutches no matter what is done.