So another question about the 79 300 SD I'm getting... that thing has a SERIOUS shake at idle but when you give it just a little gas it smooths out. Anyone ever have this problem? I'm thinking motor mount but just wanted to get some thoughts.

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1983 240 D-SOLD
1979 300SD

Motor mounts
Rack Damper
Valves need adjusting
Injectors cleaned/tested
Timing
Fuel supply/filters
Air intake/filter

Take your pick

Danny

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1984 300SD Turbo Diesel 150,000 miles

OBK member #23

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There was an upgraded rack damper bolt to correct this problem. The one I have is gold anodized in color.

Jim

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14 E250 BlueTEC black. 45k miles
95 E320 Cabriolet Emerald green 66k miles
94 E320 Cabriolet Emerald green 152k miles
85 300TD 4 spd man, euro bumpers and lights, 15" Pentas dark blue 274k miles

The described problem does sound like an air leak vs. RD bolt, if constant. I cured an always flucuating idle, not violent shaking, by replacing the RD bolt. I have experienced said shaking in the CD and SD occasionally, and chalk that up to ULSD. Won't hurt to install new motor mounts.

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83 SD

84 CD

I'll try the motor mounts first. I really dont think its the valves. When I give it just a little throttle it is smooth as silk. Excuse my ignorance but what and where is the RD bolt, I want to check into it.

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1983 240 D-SOLD
1979 300SD

Actually, valve adjustment is what I would check first. I'm not sure why you don't think it's valves unless you've actually checked. The problem is they tend to be too tight.

The rack dampner (RD) bolt is in the middle of the aft side of the IP. It's a bolt with a locking nut. (a weak rack dampner shows up as a rough idle while warm)

(BTW, just a little caution......refrain from using "gas" terminology such as "give it a little gas" or "throttle" as some will give you a little guff. We tend to enjoy "diesel" terms such as "fuel" and "accelerator".)

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Sam

84 300SD 350K+ miles ( Blue Belle )

I have a similar problem, so probably the fixes are the same as above. My '81 300D non-turbo has a rough acceleration. It idles smooth but the first part of acceleration (from 500 to 1000 RPM -just a guess b/c no tach) is rough. After about 1000 RPM it smooths right out. I thought it was my drive shaft because I know that needs balancing, but it is noticeable also while idling in park or neutral. I know a few of the valves are bit tight as I checked them the other day but did not adjust them (my mechanic is much quicker and equipped for that job). So, I'm thinking motor mounts or valves. Anything else worth checking?

The rack damper, I think is the correct name, fixed my shaking at idle. It was a PITA for me to get to it, but it is soooo much nicer now.

Was there a solution to the OP's problem?

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RT


1984 300D---Sold
1995 E420 - 106K - Brilliant Silver Metallic/Orion Gray --- Sold
1984 300SD - 151K Manganese Brown Metallic/Mostly Black --- Sold
1982 240D - 79K - Manila Beige/Palomino---Sold

I had the same issues.

I replaced the usual suspects and nothing worked.

I removed the delivery valves and cleaned them and now idles very smooth.

Do not be too quick to replace your pump, check the delivery valves first if you already checked injectors, rack damper bolt, timing.

Steve

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85 300d in progress

Replaced motor mount, all is well.

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1983 240 D-SOLD
1979 300SD

Good tip! Were the delivery valves very dirty? This is on your 617 motor? There are no o-rings in there? What is the procedure for cleaning the delivery valves, and the torque prcedure?

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85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

The delivery valves?, You took things apart down in there and changed the copper seals? Were they leaking or the engine was just running rough?

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1985 Euro 240D 5 spd 140K
1979 240D 5 spd, 40K on engine rebuild
1994 Dodge/Cummins, 5 spd, 121K
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