Hi there!

I've just replaced the flex disc/hardy disc on my 300TE, 89. Hoping this would reduce my hard shifting. But no...
Symptoms

• Hard "thunk" when going into R or D (Makes my brakes "sqiiiiik")
• Hard "thunk" in all the gears upwards, down a bit better
• Better when very low trottle

It could feel like it might be the diff, since when I was turning the propeller-shaft it seems like I could replicate the "thunk" - it was from turning first one way, and then quickly change direction. - not totally sure about this, was sweating under the car in 30'c - but will follow up on this.

I've been reading about checking vacuum pressure and adjusting the modulator.
I've read these two pages: http://www.benzworld.org/forums/w201...l-replace.html and Mercedes-Benz Transmission, Steve Brotherton, ImportCar, February 2002 but they are for the 722.4 and/or diesel. But I'm having difficulty in figuring out where to plugin a test Gauge and what the pressure should be?

Could a gauge like this work: http://www.ebay.co.uk/itm/Oil-pressu...item5d4cce5be2 ? and where to plug it in?

I also have a vacuum "fuel efficiency" gauge, which works as it should, had a leak once, fixed it, but no change in the shifts. But I don't know if its related to the gearbox vacuum or usefull to leak finding.

The other things I will try is changing the oil and look closer on the diff/driveshafts. But I would really want to know about the vacuum is fine for the gearbox

Welcome to the forum. There are a number of good suggestions in this link that may help.

http://www.peachparts.com/shopforum/tech-help/178790-1990-300e-m103-clunk-when-shifting.html

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1993 400E, 256,000 miles (totaled)
1994 E420, 200,000+ miles
1995 E420, 201,000 miles

might check if vac is going to transmission

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

Yes, check vacuum levels at the modulator on the transmission, also, what is your engine idling at in park? If its idling too high its going to slam into reverse and drive. An M103 should idle around 700 in park and about 550 in drive or reverse....

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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)

on my 300E 1988 the 2 rubber bushings that hold the back of the rear diff are shot. It makes a clunk when going into drive or park,also when I hit the kick down while accelerating or taking my foot out of it during acceleration it is very bad!
Jack up the back of thre car and release the park brake but leave the trans in park so the drive shaft does not turn.have someone turn one of the tires back and forth while watching the bushings to see if the diff jumps up and down you will know right away if they are shot

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88 W124 3.0
96 R129 119eng
06 ML350
98 ML320 sold
02 CLK55 amg