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1983 300SD Questions/Concerns

  #1  
Old 08-19-2012, 05:59 AM
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Exclamation 1983 300SD Questions/Concerns

So about a month ago I purchased a 83' 300sd. I have been reading up some and watching a few videos, ect. I have some issues and concerns with the car which might help others out as well. I love the car and want to restore it and customize it. The tach is not working, as I have pinpointed it down to the tach amp under the hood needs to be replaced. Any good places to purchase this without spending 140.00? Well, when im driving down the highway, it seems as if the car is revving pretty high. Cant tell you the rpm but its pretty loud. I really dont feel comfortable bringing it above 65mph. I have adjusted the ALDA screw because of a very noticeable lack of power soon after I bought the car. Now it seems the cold starts are alot more rough, and sometimes motor shuts off completely. It has a decent amount of white smoke when cold and seems to go away a little after the motor warms up. The transmission seems to hesitate when cold as well, taking a second to shift up into 3rd and 4th. Its like it has a clutch, it will rev-up then go into gear. This happends with 4th every time whether cold or not. It seems to shift between the gears pretty fast as well, hardly giving 2nd a chance to build up? Anyway, main issues are the rough idle, white smoke, ALDA, transmission shifting and speed issues on the highway. Anybody got some insight for this noob? I love the car and want to get er running right. Car has 280k on the odo. Trying to get the car performing back to spec, and maby a few ideas on some upgrades as well as fixes for the issues.
 

Last edited by re300sd; 08-19-2012 at 06:19 AM.
  #2  
Old 08-19-2012, 07:43 PM
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Turn it back where it was. The ALDA should be the absolute last thing touched when diagnosing low power. It will only mask any real problem then cause excessive black smoke when the real problem is resolved.
I realize this now, but it has been turned all the way out. I don't know original position of it. I turned it back down a few turns until the rev was still quick with a little black smoke at full throttle rev. Is there an original setting I can turn it to? Ex. open, then three turns down? I have replaced the fuel filter with a new oem purolator from advance auto and the clear in-line filter as well. Changed the oil to 15-40 I believe full synthetic rotella. Changed oil filter from advance auto or napa, WIX filter. Straight exhaust 2.5 all the way back. New air filter, paper filter. Cleaned the banjo on the back side of the intake manifold. Put on new stock 17in E-500 rims and tires.
 
  #3  
Old 08-19-2012, 07:53 PM
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On the timing issue for the camshaft and injection, also when you say
Retarded injection timing. Set it to 24-26*BTDC.
Do I need to replace the timing chain as well? I am not sure if this has ever been done. Is there a link to where and how I perform the timing adjustments you quoted and replacing timing chain? Is replacing the timing chain a real undertaking?
 
  #4  
Old 08-19-2012, 08:01 PM
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The correct valve adjustment procedure is at:

Mercedes Diesel Valve Adjustment Procedure

is this correct?
 
  #5  
Old 08-19-2012, 08:07 PM
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Also, im guessing performing all of the above should correct the extremely rough idle? The original priming pump is leaking diesel down onto the drivers side motor mount. The mount looks pretty rough, so im guessing that should be replaced as well. Have any links to that, and is that a pretty difficult undertaking? I have a new style priming pump im guessing I should install pretty soon.......
 
  #6  
Old 08-20-2012, 08:58 PM
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Okay, well I did what you said in regards to the ALDA

No, the only way to correctly calibrate it is with the pump on a test bench.
The ALDA can be "close enough" adjusted by turning it until there is little to no visible smoke from the exhaust when the throttle is mashed from a standstill.
CW reduces fuel available at low-boost, CCW increases. It will not alter maximum power.
I got it to the right setting I believe. Now, the original problem is back. It seems like when I was leaving the house, just starting to get on the accelerator.......one second I had good/normal acceleration, and the next second it was like the boost was gone, no power hardly at all....then back for a second......then gone.....then back for a second......then gone.....and so on. Its like intermittent. For the most part, there is something obviously going on. I remember now, this is the reason I messed with the ALDA in the first place. Anyway, its (ALDA setting) back to normal (i believe) but now this problem......The main problem. I have cleaned the banjo off the intake manifold, and the line it runs from. So I know its not that. Any ideas or places to look/check?
 

Last edited by re300sd; 08-20-2012 at 09:01 PM.
  #7  
Old 08-21-2012, 12:56 PM
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Originally Posted by ForcedInduction View Post
Overboost protection.
When boost goes above 16psi the air signal to the ALDA is vented to prevent engine damage. Boost goes below 16psi and the cycle repeats.

Check your wastegate hose.
Or maybe the air getting into the system at the leaking prime pump?
 
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Old 08-22-2012, 03:51 AM
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Tomorrow (today) is my day off work, so I am going to check out both and I will let you know if either fixes the problem. Thanks for the input. On the wastegate hose, is there something specific I should be looking for? Leak? Clogged line?
 
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Old 08-22-2012, 11:46 AM
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Are you referring to the short hard plastic line off the back of the wastegate that runs only about what looks to be 6in long when taken off?
 
  #10  
Old 08-23-2012, 03:00 AM
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Replaced the leaking pump, and checked the line off the wastegate. Small stock plastic line seemed a little restrictive and seemed to be the cause of the problem. Replaced the line with 3/8 fuel line and with both fixes, power is restored! Thanks for that one. The idle is still rough as can be however, think its going to shake the car apart! Im guessing the valve adjustment and timing issues are the cause? As well as the smoky exhaust?
 

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