Anyone try flushing the transmission through the cooler lines. I was thinking of just unscrewing one of the transmission cooler lines, overfill the transmission with new fluid, start the car and wait until new fluid starts pouring out.

Good idea on an older 560SEL?

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2001 E55

2001 E320 Sedan

2001 Subaru Legacy

2006 SLK280

2016 Subaru Outback 3.6

No, not a good idea. Drain the transmission and torque converter, replace the filter. Re-install pan, fill with 4.5qts.....start engine, let it idle a couple minutes, then add the remaining 2.5-3qts.

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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)

Actually, for the later model cars, flushing the transmission via the cooling lines is exactly what MB recommends in cases where it's deemed necessary. For routine maintenance though, I'd say it's overkill.

I think it's silly to use the cooler line method for cars with a torque converter drain plug. The cooler line method is more messy and you still get mixing of the fluids where new fluid is pushing out the old.

The cooler line method is only messy if you try to use the return line.

I did put a short piece of hose aimed up on the cooler fitting I removed too.

If you drain to clear 2L bottles its also very, very easy to see what is
coming out.

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1985 300D 198K sold
1982 300D 202K
1989 300E 125K
1992 940T

"If you dont have time to do it safely, you dont have time to do it"

"The democracy will cease to exist when you take away from those who are willing to work and give to those who would not."

Real Men drop the pan clean it,change filter.

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1999 w140, quit voting to old, and to old to fight, a god damned veteran

Anyone agree with this method ?

Yes. That is the correct method for changing the ATF.

That is the method published in the shop manual.