I just referenced a Service Manual for 616/617 engines and also have done a visual inspection on my 1977 240D.

I have concluded that the 1977 240D does NOT have a Rack Dampener Screw.

If I read the MB schematic correctly it would appear that on the 240D one has to remove a cover, then the governor spring and reinstall with compensating washers (shims) to adjust engine idle speed.

Am I reading this correctly??? The magic of online adjustment (with engine running) seems to be denied the 240D owner. Not nice. Why???

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Dionysius

I believe a 77 240d should have a manual idle control knob on the dash to the left of instrument light intensity adjustment knob.
I also think that the rack dampener bolt and the idle adjustment bolt are two different things on the later model engines.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Yep, I do have an Idle Adjust Knob but I would think this is a coarse idle adjustment and is different from the Rack Dampener.

The 300SD folk claim great that their Rack Dampener is a magic elixir of sorts for them to smooth out vibrations etc. My question is why is this conspicuously absent on the 240D since both engine injection systems are so much alike.

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Dionysius

Nope, 240D's and non-turbo 300D/CD/TD's do not have a rack dampner screw.
The course adjustment is on the injection pump in between IP and engine {vertical screw with lock nut. Don't overtighten or the bracket on IP will snap }.
**see item 3 & 4 in first post of this thread:
help! anybody

Adjustment knob is the fine adjustment, and helps you compensate for cold starting, running with AC, etc......
Rack dampner screw is not a "magic elixer", just an adjustment device. No magic there.......

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Jimmy L.
'05 Acura TL 6MT
2001 ML430 My Spare

Gone:
'95 E300 188K "Batmobile" Texas Unfriendly Black
'85 300TD 235K "The Wagon" Texas Friendly White
'80 240D 154K "China" Scar engine installed
'81 300TD 240K "Smash"
'80 240D 230K "The Squash"
'81 240D 293K"Scar" Rear ended harder than Elton John

Since we are talking about the Rack Damper Bolt. Is there anyone who knows what causes the engine to idle smoothly when it is cold and not so smooth when it is hot. Even with the Rack Damper mine shakes more after it run about 20 minutes. Nothing I have read in any of the threads or in the books I have can explain the cause.
My Volvo diesel runs smoother and with the engine cold or hot vibrates the same.

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84 300D, 82 Volvo 244Gl Diesel

One post I came across said the engine shocks could be a solution. My 240D 1977 does not have engine shocks however. A shock could become less effective when hot from engine heat pickup and fail to dampen some vibrations.

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Dionysius

Have you adjusted the RD bolt? Or maybe you need to replace.

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83 SD

84 CD

I changed my motor mounte about 2 weeks ago but did not put the engine shocks on until about 3 days ago. So I drove without the eingine shocks for more than 1 weeek. The engine still acts the same, runs smooth at idle when the engine is cold but after 20 minutes or more of driveing and the engine is good and hot the engine vibrates more.
My guesses have been that it is related to oil viscosity or the transmission (automatic) is somehow putting some slight load on the engine when it gets hot but I was hoping someone who reads Manuals and ect. would know why the factory said (not the symptom but the cause they were fixing) the put the Rack Damper on.

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84 300D, 82 Volvo 244Gl Diesel

After doing everthing from valve ajustment, rebuilt injectors on down to changing Motor mounts (engin shocks are good) and a Gold Rack Damper pin (that I have adjusted several times just to see what it would do). Each thing that I did helped alittle and I am OK with how my engine runs.

My question was a little deeper than that. I am trying to find out the reason (what is happening) to cause the enginge to run smoother when it is cold and rougher when it is hot. There has to be some underlying cause.

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84 300D, 82 Volvo 244Gl Diesel

Or the ability of the shocks to dampen vibrations deteriorates with heat OR and this is the most important OR
any some and all of the above and then some.....




Stuggart have never been good at giving out any information as to what drove their design decisions or their updates. In reality the isolation of vibrations is a complex topic and it is like having a tiger by the tail. As I studied their manual yesterday I have to conclude that they must think the mechanic out there has an average IQ of 170. I found myself asking so many WHY and WHY NOT questions that I would have given a fortune to have had a few answers or a real-time group discussion.

I have found that the use of a stethoscope is invaluable since I was pieceing together some theories to satisfy myself at least (many probably totally incorrect) as to what could be happening. The comparison of resonances being referred as you loosen, tighten, remove items was great but it is hard to use a stethoscope as you drive down the highway at 70 mph.

These cars are the cheapest fun you can have and you do not get into trouble. Elliot Spitzer should have had such a hobby!!!!!!!

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Dionysius

NOT engine shocks: They are dampers. Same as the ones on the axles. Misnomer.

Its the springs that absorbe shocks.

P E H

A shock is a damper and is different from a spring.

If a spring is perturbed it oscillates.

To limit the number of oscillations a shock or damper is deployed.

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Dionysius

Dionysius.

Yes a damper is applied to reduce occillations, But that is not a shock absorber. To absorb shocks there must be something that can store energy I.E. a spring.

Its the same in electrical circuits: A capacitor (spring) absorbs electrical shocks and a resistor (friction device) is used to dampen the capacitor vibrations.

Possibly gas filled dampers would absorb some shocks

P E H

This is my best guess..same exact problem..pinched the return line hose closed,the special banana hose,for a few seconds only or you will blow a injector return line off..On my engine,it smooths it out!..The best guess is the fuel pump gets weak as it gets hot and doesn't produce the pressure that is needed for the IP. Maybe a new pump that is needed?

Get the check valve rebuild kit.