Hello all, I am a new proud owner of a 1984 300D Turbo that I have inherited from my father. The car has 142K on it and is running very well.

My problem: When I put the car in drive, the rear end drops about 1" and I can feel it hit a bottom. When I put it in reverse, the rear end rises about 1". Is this normal? As far as I can tell, there isn't a hydrolic level system on this car.

This forum has been a great help to me so far in understanding the diesel engine and the 'quirks' of the 300D's. Thanks to everyone for all the great info.
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doug18106
'84 300D Turbo 142K

Check the differential mount and make sure it has ANY rubber left. While there, check the diff oil.

Check diff play with both rear wheels off the ground.

LUK what you find.

__________________
1984 300D Turbo - 4-speed manual conversion, mid-level resto

1983 300D - parts car

1979 300TD Auto - Parts car.

1985 300D Auto - Wrecked/Parts.


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"If you don't know where you are going, any road will get you there". Lewis Carrol

Thanks TomJ

How do I check the differential play?

Is it the motion of the tires when you pull the top the bottom then right then left?

If yes, how much play can there be?

Also, I already bought a jug of Mobil 1 gear oil to change out the differential.

Cheers

Jack up the rear and turn the driveshaft by hand and see how much rotation before the tires move. Also, check some of the other posts on ltd slip diffs. The old dodges with a posi-trac type rear end used to do just what you're describing under hard accel.

I'd suspect the diff mount or other mech issue though if you notice it that much. Also could just be the shocks are VERY shot. Check them for oil leaking out.

__________________
1984 300D Turbo - 4-speed manual conversion, mid-level resto

1983 300D - parts car

1979 300TD Auto - Parts car.

1985 300D Auto - Wrecked/Parts.


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"If you don't know where you are going, any road will get you there". Lewis Carrol

Mine does that. Also it carries the front high running down the road a bit, if you suddenly lift off the throttle from a steady highway speed you can feel the front of the car drop a bit.
I assumed it was all from the independant rear suspension.
~shrug~

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One more Radar Lover gone...
1982 VW Caddy diesel 406K 1.9L AAZ
1994 E320 195K

Forgot to mention (or maybe assumed you already checked), but the motor mounts and shocks can allow the engine to "torque" the car if bad.

Check those too.

__________________
1984 300D Turbo - 4-speed manual conversion, mid-level resto

1983 300D - parts car

1979 300TD Auto - Parts car.

1985 300D Auto - Wrecked/Parts.


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"If you don't know where you are going, any road will get you there". Lewis Carrol

Are you sure that your car doesn't have a self-leveling rear suspension? My 1983 300TD wagon used to do the exact same thing; the rear end would raise up in reverse, drop in drive. If your car does have the self-leveling system, it could be an easy fix. Check for a hydraulic fluid tank under the hood. Mine is located in the front left of the engine compartment. You might just be low on hydro fluid. If that's not it, you can adjust the linkage in the rear of the car coming out of the control valve. Disconnect the linkage, and lift up. If it's like my car was, you'll watch the whole rear end of your car head for the sky. Well, that's my two cents. Of course, that's assuming you have a self leveling system.

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1984 300TD Wagon--Astral Silver--Retired
1983 300TD Wagon--Dark Blue--Retired

My '85 does it as well. It doesn't bother me one bit.

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DJ


84 300D Turbodiesel 190K with 4 speed manual sold in 03/2012

All cars do this to some extent... basic physics of weight transfer...
However, it bottoming out on anything means something is wrong...
But I would check the condition of the shocks and springs first...

My 84 did it, and my 83 does it. The only thing that ever concerned me was when the 84 took a few seconds to decide to get into gear. It shouldn't bottom out, just move a little. How does the wheel gap look compared to your front wheels? It should be about the same but they tend to decrease in age as the springs sag.

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Jeff M.
Mercedes W123 DIY pages are now located here.
1983 / 1984 300D Sold
2000 CLK430 Cabriolet ~58k Sold
2005 Avalanche 4x4 ~66k

I have to clarify my previous reply, mine does it but it doesn't bottom out. I think its kind of like any of my other automatics.

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DJ


84 300D Turbodiesel 190K with 4 speed manual sold in 03/2012

Yea I editted mine a little too. I think that is pretty well normal for any automatic RWD vehicle, some it is more noticeable than others. My dad's truck doesn't do it noticeably but given the slightest hill it also rolls backwards.

__________________
Jeff M.
Mercedes W123 DIY pages are now located here.
1983 / 1984 300D Sold
2000 CLK430 Cabriolet ~58k Sold
2005 Avalanche 4x4 ~66k

TomJ - I jacked up the rear and the driveshaft will turn about 1/8 - 1/4" before stopping. Is that bad?

Also, I noticed about a 1" gap on the bottom of the differential mount.....looks like a suspect has been found....I will order a new one this week.

The shocks don't look like they are leaking, but probably need to be replaced soon anyway. When the funds become available......

wolf_walker - The front end stays level, it doesn't move much when I let off the throttle either...so I think it is ok.

1983 300TD - I'm sure I don't have the self leveling suspension....no extra resevoirs, hoses, lifters, etc. Thanks anyway.

BoostnBenz - The wheel gap is ok...she only drops in gear...I would think if she had sagging springs would sag all the time (like my wife)...unless, of course, they are held up by a jack or bra....haha

As I said earlier...I'll get a new differential mount and see if that helps...I'll let you know.

Thanks all for your help