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  #1  
Old 10-20-2004, 11:48 PM
WANT '71 280SEL's Avatar
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How can I smoothe idle when there's no dampner pin?

My 1979 300SD doesn't have a rack dampner pin on the back of the IP. I don't know if it's a different IP or what but there certainly isn't one there. Would they have put the pins elsewhere on the '79 SD's? I have replaced the motor mounts which helped greatly, but it shakes mostly on hot idle in drive. When you put the car in park, it doesn't shake nearly as bad.
(go figure)
Thanks
David

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Old 10-21-2004, 08:05 AM
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Same problem with my 1980 300SD.....No Pin. Have replaced the mounts and the shocks. Just set the valves and did the "Diesel Purge" thing and it still shakes, more when hot and decellerating with the engine RPM reducing
at about 900-1000.

Bob Moore
Tarpon Springs, FL
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  #3  
Old 10-21-2004, 08:12 AM
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There aren't any pics on the side or any such place that can be adjusted? Surely a doctor didn't pay $32k for a shaking, clattering machine?
Thanks
David
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Old 10-21-2004, 08:56 AM
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After the things mentioned.... or actually before, the most important items for smoothness are the injectors and precombustion chamber/ holes... all the injectors need to pop at the same pressure and have a good spray pattern and the pintle in the precombustion chamber needs to be in good shape... and the holes to distribute the fuel must be clean...
This is the point at which differences between cylinders show up as different amounts of horsepower being produced by different cylinders... and then can show up as harmonic vibrations by the engine.
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Old 10-21-2004, 12:02 PM
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Just in case you overlooked the obvious, the two engine shocks make a big difference in vibration transmitted to the body, as are condition of the motormounts.

Speaking as an owner of a 1979 300SD who has been through it.
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1979 300SD W116
1983 300D W123
1975 Ironhead Sportster chopper
1987 GMC 3/4 ton 4X4 Diesel
1989 Honda Civic (Heavily modified)
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Old 10-21-2004, 01:30 PM
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I've replaced the motor mounts. The engine shocks were very stiff to compress, but I thought they were there to mainly dampen the engine vibration when it's shut off. Does your '79 have a dampner pin? This isn't just a vibration, it's more of a shaking. I ran diesel purge thorugh and that didn't seem to do much. Also, to rebuild them don't you just take the injectors apart, clean them and replace the nozzles?
Thanks
David
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Old 10-21-2004, 07:11 PM
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Quote:
Originally Posted by WANT '71 280SEL
I've replaced the motor mounts. The engine shocks were very stiff to compress, but I thought they were there to mainly dampen the engine vibration when it's shut off. Does your '79 have a dampner pin? This isn't just a vibration, it's more of a shaking. I ran diesel purge thorugh and that didn't seem to do much. Also, to rebuild them don't you just take the injectors apart, clean them and replace the nozzles?
Thanks
David
Well if both shocks were VERY stiff maybe they were good. I assume the rubber isolated mounts on the ends were good also, Mine were shot when I did mine.

No those shocks make a HUGE difference will running, take my word for it. I ran it with new motor mounts and NO shocks , shook like an SOB, few days later one shock came in with mounts, made a difference but still shook, week later the seconf shock and mounts shows up and I put it on......DAMN no more shake. Smooth at idle now. If the rubber seperates from the metal it will slide in and out without the shock even moving. Mine did that before I replaced them.

No I don't see a rack damper on mine either.

About injectors?????????????? never did it but there was a thread that was very, very informative along with pics in the last year, try a search.
__________________
Proud owner of ....
1971 280SE W108
1979 300SD W116
1983 300D W123
1975 Ironhead Sportster chopper
1987 GMC 3/4 ton 4X4 Diesel
1989 Honda Civic (Heavily modified)
---------------------
Section 609 MVAC Certified
---------------------
"He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche
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Old 10-22-2004, 02:16 PM
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try adding a few litres of fresh vegetable oil to your next full tank of fuel.see if this improves smoothness and noise levels.a cheap fix in my opinion
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  #9  
Old 10-22-2004, 07:52 PM
boneheaddoctor's Avatar
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The mounts I am talking about are the upper ones, the rubber insert seperates from the steel bracket and then poof, they no longer have a solit attachment point on one end and they do nothing.

__________________
Proud owner of ....
1971 280SE W108
1979 300SD W116
1983 300D W123
1975 Ironhead Sportster chopper
1987 GMC 3/4 ton 4X4 Diesel
1989 Honda Civic (Heavily modified)
---------------------
Section 609 MVAC Certified
---------------------
"He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche
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