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  #1  
Old 07-01-2016, 11:05 PM
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rough idle

I'm throwing in the towel on my rough running car. Any last ideas? Below are what I've done and a video of the car running.

-adjusted valves, new idle screw, rebuilt injectors, replaced delivery valves and Springs, new filters, new lift pump, new motor mounts, adjusted idle speed. Car has zero blow-by but didn't check compression.

https://youtu.be/80Rw27TZ3jU

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1983 300 Turbo-"Nora"
1983 240D Auto "Lucia"-slowest on earth-1st love
1985 300 Turbo-Blue Goose-slowly plucking parts

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  #2  
Old 07-02-2016, 12:55 AM
Diesel effcient
 
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Does that motor have electronically controlled idle? If so try to unplug that and see if there's any difference?
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  #3  
Old 07-02-2016, 05:43 AM
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Wow, that engine's rocking pretty hard. My gut instinct was motor mounts, but you did those. I'm still leaning towards something like that, though, because to my ears, it sounds pretty good when it's running.

When you did the mounts, did you install new engine torque dampers or just reuse the old ones? And how solid were the torque damper mounts?

How about the transmission mount? That made a real difference in two of mine that felt a little jumpy.

If all else fails, just do what I do with my wagon...enjoy the back massage! Good luck to you!
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  #4  
Old 07-02-2016, 12:54 PM
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The engine shocks are in pretty bad shape but I was told that it wouldn't affect the idle that much. The transmission mount looked in good shape.
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1983 300 Turbo-"Nora"
1983 240D Auto "Lucia"-slowest on earth-1st love
1985 300 Turbo-Blue Goose-slowly plucking parts

http://i117.photobucket.com/albums/o...ly15/mbsig.jpg
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  #5  
Old 07-02-2016, 12:55 PM
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I adjusted the idle through a screw on top of the IP pump. The car is intolerable with that much shaking
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1983 300 Turbo-"Nora"
1983 240D Auto "Lucia"-slowest on earth-1st love
1985 300 Turbo-Blue Goose-slowly plucking parts

http://i117.photobucket.com/albums/o...ly15/mbsig.jpg
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  #6  
Old 07-02-2016, 01:28 PM
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bad compression will be really noticeable at idle. Try cracking each injector one at a time and see if that stops the shaking. This will tell you if one cylinder has low compression. Even if most of the cly's are ok.. .but one is low... it may shake horribly at idle.
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  #7  
Old 07-03-2016, 04:14 PM
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Tried that already. Car idled much worse by cracking the injectors one by one
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1983 300 Turbo-"Nora"
1983 240D Auto "Lucia"-slowest on earth-1st love
1985 300 Turbo-Blue Goose-slowly plucking parts

http://i117.photobucket.com/albums/o...ly15/mbsig.jpg
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  #8  
Old 07-03-2016, 05:11 PM
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Engine sounds smooth, however you can almost hear the rack inside the pump shaking in that video. I suggest you slow the idle down to about 700, it sounds a little fast right now, and then adjust the rack damper screw wth engine idling hot. If this doesn't help my next move would be to perform a compression test.

Did you adjust the delivery valves on the injection pump, the 2 13mm nuts that hold the adjustment should not be touched unless the pump is being calibrated on a machine.
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1985 300TD Turbo Euro-wagon
1979 280CE 225,200 miles
1985 300D Turbo 264,000 miles
1976 240D 190,000 miles
1979 300TD 220,000

GONE but not forgotten
1976 300D 195,300 miles
1983 300D Turbo 175,000 miles

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  #9  
Old 07-03-2016, 08:14 PM
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I didn't touch the adjustment shims on the delivery valves. The shake was there before I installed the set of delivery valvles/springs. I did try to play with the rack damper screw before I adjusted the idle up so I doubt that would help either.
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1983 300 Turbo-"Nora"
1983 240D Auto "Lucia"-slowest on earth-1st love
1985 300 Turbo-Blue Goose-slowly plucking parts

http://i117.photobucket.com/albums/o...ly15/mbsig.jpg
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  #10  
Old 07-03-2016, 08:36 PM
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New or old rack damper bolt?

-Rog
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  #11  
Old 07-03-2016, 09:37 PM
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New rack damper bolt
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1983 300 Turbo-"Nora"
1983 240D Auto "Lucia"-slowest on earth-1st love
1985 300 Turbo-Blue Goose-slowly plucking parts

http://i117.photobucket.com/albums/o...ly15/mbsig.jpg
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  #12  
Old 07-03-2016, 09:52 PM
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I couldn't tell if you had a regular hose on the return line or a "cigar" hose. I had read that the purpose of the "cigar" configuration was to help smooth out the idle.
It does sound good to me other wise.
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  #13  
Old 07-03-2016, 10:22 PM
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assuming the valves and coompression are in great shape...


and since I have the tools and parts, I would:


check the injection timing. If it was over 4 degrees off, I would inspect the timing shaft which turns the injection pump via the timing gear.

then swap out the injection pump for a good one..



important:

if you hear a ticking of a light knocking near the vacuum pump, you may have a loose bolt on the injection pump timing gear. this will cause the shaft to break and spin inside of the gear.
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  #14  
Old 07-03-2016, 10:36 PM
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oh....

before all that, i would check fuel pressure and air in the fuel supply.
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  #15  
Old 07-04-2016, 12:33 AM
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Quote:
Originally Posted by brownrice78 View Post
I didn't touch the adjustment shims on the delivery valves. The shake was there before I installed the set of delivery valvles/springs. I did try to play with the rack damper screw before I adjusted the idle up so I doubt that would help either.
I would back the damper screw out, lower idle speed and then turn the rack screw in until you can tell it idling smoother, it just has to apply a little pressure to the rack to work properly, remember the higher the idle speed the farther the rack damper screw has to be screwed in to reach the rack.

Are you sure that all injectors are opening very close to the same pressure?

Like JT said, assuming there is no air getting in fuel system and you have good fuel pressure, you can pinch off the cigar hose to verify low pressure isn't the cause.

Did you check for chain stretch while you had the valve cover off?

i would do a compression test on the engine and hope you have less than 45 psi difference between the cylinders.

Also, has the engine always had a shaky idle or did this come on all of a sudden?

__________________
1985 300TD Turbo Euro-wagon
1979 280CE 225,200 miles
1985 300D Turbo 264,000 miles
1976 240D 190,000 miles
1979 300TD 220,000

GONE but not forgotten
1976 300D 195,300 miles
1983 300D Turbo 175,000 miles

http://i42.photobucket.com/albums/e3...e485-1-2-1.jpg
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