As you saw in an earlier thread I swapped out the radiator on my 85 300 SD. Unexpected benefit. There was junk that I believe was impeding the flow of transmission fluid. I have noticed that the shift from first to second under strong acceleration has gone from hard to smooth. I can feel the transmission synchronizing instead of hammering into gear. It was disconcerting at first since I had never felt it since I owned the car but it is much better than it banging into gear. I would suggest checking this out if you have this nagging transmission problem in your early 80's turbo diesel.

How is the temperature reading on instrument panel. Does it point to lower value after the radiator change?

My 1992 300D shifts hard even when I accelerate very gently. Especially from 1 to 2. Very smooth shift happens occasionally.

I read that some MB's are designed to up-shift a little hard at full throttle.

__________________
1992 300D 2.5 turbo diesel. 319 k miles.
124.128 chassis, 602.962 engine, 722.418 tranny.

doesnt the W124 chassis auto start in 2nd?

__________________
2002 VW Golf TDI-169,000 miles B20

The shifting still feels different but I still get hard shifts. I believe the temp is in the low 90's though I believe the send unit is a little weird but that is where it settles most often. I sat in traffic waiting to get out of talladega for over an hour at idle without moving and the guage sat right near 90C.

__________________
My Daily : 96 E-300 Diesel with 195,000 miles
Retired: 92 300D 2.5 T 345K miles and for sale
Retired: 95 E320 157K miles and currently parked with blown engine

Both retired cars are for sale as is my w124 shop inventory

Before year 91, it starts from 2nd gear unless the driver press the pedal much.
But mine is 92 model (manufacturered in late 91), and starts from 1st gear even at gentle start.

I also get around 90 degrees or a little lower. On the highway, about 85 degrees or a little lower than 85 (but a little higher than 80) due to more cooling by air.

Do you have both hard up shifts and hard down shifts?
I never experienced hard downshift. I will go to highway some day, and try to coast to stop without breaking to see how it downshifts. Oh, I can feel the down shift when I press gas pedal much while I am driving in 4th gear. But it cannot be called hard shift when compared to 1 to 2 up shift: bang sound as if someone hit my car with rubber hammer, and my car's front lifts up due to sudden acceleration.
Two mechanics had an opinion that it was OK for a such an old MB diesel car. One mechanic said he could make it shift very smooth but it might burn the transmission.

__________________
1992 300D 2.5 turbo diesel. 319 k miles.
124.128 chassis, 602.962 engine, 722.418 tranny.

Both of our SD's start off in first every single time. Occassionally when mine is really warmed up and I am on a downward slant or have just come off the freeway it will start in second, otherwise it never does, and the other SD I've never witnessed it do it even once. I'd love it if it did though, it'd be so much smoother and is fine for 80% of all take off's, except on hills...

__________________
-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)

Hard shifts are always up shifts here. Based on your comment I am thinking you believe the problem is it is starting in first gear. I don't usually count the shifts. I will pay attention though next time I get in. It may happen more often when I floor it and that would definitely be first gear.

__________________
My Daily : 96 E-300 Diesel with 195,000 miles
Retired: 92 300D 2.5 T 345K miles and for sale
Retired: 95 E320 157K miles and currently parked with blown engine

Both retired cars are for sale as is my w124 shop inventory

In my case, lubricating throttle linkages made the upshift a little bit softer.

__________________
1992 300D 2.5 turbo diesel. 319 k miles.
124.128 chassis, 602.962 engine, 722.418 tranny.