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  #1  
Old 10-02-2003, 03:24 AM
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Question Idling problems when engine is cold!

I just purchased an 82 300SD about 3 weeks ago, and I'm fairly new to this forum and to diesels, never own one before, so I hope someone out there can help me out.
It started fine when I got it home for the first week, morning temp about 45-50*F. I did some routine maintenance on the car cause it looked like it had been neglected for sometime.
I changed the air and fuel filters, primary and secondary,both were very dirty. Checked calibration and cleaned one of the injectors. All injectors now have a good spray pattern. A friend had a injector hand pump to check calibration and spray pattern. I adjusted the valve clearances to the Haines manual specs, cold engine, intake 0.10mm, exhaust 0.35mm.
Also now the temperature in the morning has dropped to about freezing over night and I find the car will not start/idle without me having to depress the accelerator and hold it to about 800 to 1200 rpm for approx 30 secs to 1 min. It will then idle. If I don't keep the accelerator depressed it runs about 500-600 rpm and then stalls. I will leave it idle for 5 min or so and then start to drive, the first stop sign or red light I hit, usually about 1 block it stalls. It starts easily, then it's fine till I get to my final destination.
Can anyone help me out here? I've done a search and haven't found anything on any of the threads with the same problem. Does anyone know if there's a fast idle solenoid for colder weather?

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  #2  
Old 10-02-2003, 12:26 PM
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Have you checked the glow plugs? I don't believe there is a whole lot you can do about this otherwise, it is just a result of the compression getting lower with wear. I don't like it how it stalls there, perhaps you aught to do a compression check. The injection system is completely mechanical, no solenoids for idle. There may be an idle adjustment screw, but that'll change it all the time (don't recommend this). There is a chance it could be a result of your fuel, do you use any additives? I don't think there is anti-gel in diesel yet so this probably didn't help the cause. I normally give it a little throttle (just enough to hear the idle change) for the first five seconds or so out of habit then it is fine, it probably would be if I didn't but would be running slower.
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Last edited by BoostnBenz; 10-02-2003 at 12:38 PM.
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Old 10-02-2003, 12:48 PM
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Wildrose,

500 to 600 RPM is too low for idle speed. Try turning the idle adjust screw (on engine side of injection pump) for a faster idle at 750-800 RPM.

Its not the GP because they are turned off the instant the started cranks the engine. Their job is finished once the engine starts.

P E H
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Old 10-02-2003, 01:50 PM
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How long are you running the glow plugs before starting the engine? Try running them until you hear them stop heating (listen for a click). Also do a resistance check on the plugs.

It's common for an older diesel to run a bit rough without throttle assitance shortly after a cold start. But it should smooth out after a few seconds, especially after you idle it at a higher RPM for a while. At least that's the common behavior my 3 cars exhibit.

I agree with the recommendations of raising the idle to 750-800 (warm), and also using some diesel fuel additives that raise the cetane. If that doesn't help I'd say a compression test is the next step.
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Old 10-02-2003, 07:31 PM
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Quote:
Originally posted by P.E.Haiges
Its not the GP because they are turned off the instant the started cranks the engine. Their job is finished once the engine starts.
Yea, you're right I was thinking about this as I was pulling out of the driveway today. Being the problem is upto a minute later then it can't be the GPs.

The idle speed however is just something that happens while the motor is kicking and trying to keep running. Odds are it idles at the right speed when warm, but when cold it can hardly keep itself firing.
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Old 10-02-2003, 08:16 PM
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Something obvious that might be overlooked is taking up slack in high idle adjust cable at screw fitting where it grabs linkage..... Am assuming the SD carries the same high idle adjust knob as the 240D.

Otherwise, an old trick for quicker warm-up during cold weather is carboard piece in front of the radiator.
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  #7  
Old 10-02-2003, 09:15 PM
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I don't believe that car will have the idle adjust knob. I think you have to go back to the pre-turbo models before they have one of those (W116?).
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Old 10-02-2003, 10:01 PM
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Thanks for all the replies guys, I'll try leaving the glow plugs on a little longer tomorrow morning to see if that helps. Also once the engine is warm it does idle at 800 rpm. I do also find that when it is first started that it tends to smoke a bit but once warmed up the smoke clears. I also have used an additive,called Diesel Fuel Catalyst by Red Line.
Being new at this game (owning a diesel) i just don't know what to expect. I will take a compression check. I was wondering if the injection timing could be out some also? I've read on some threads that lack of power and smoking at idle can cause this to happen, what do you guys think?
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Old 10-02-2003, 10:06 PM
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Oh! by the way, it does have a cable that is connected to the throttle linkage, but adjusting that hasn't done anything for the idle.
Will starting the car get harder as the temperature get colder? Will I need to hold the throttle down for longer periods of time?
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Old 10-02-2003, 10:11 PM
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The cable you find on the throttle linkage should be going to the transmission, goes to the top of the valve cover and runs down the passenger side of the engine in the back and disappears right?
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Old 10-02-2003, 10:16 PM
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Quote:
Originally posted by Wasuchi
The cable you find on the throttle linkage should be going to the transmission, goes to the top of the valve cover and runs down the passenger side of the engine in the back and disappears right?
Yes your right! What is the function of this cable? Is it for the cruise control?
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Last edited by wildrose196812; 10-02-2003 at 11:06 PM.
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Old 10-03-2003, 12:31 AM
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It is refered to as a "bowden cable" by adjusting it you can change the shift points of the transmissions. Yes the problem will get worse when it gets colder out. Yes you will have to hold it longer, this is assuming you can get it running.

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Mercedes W123 DIY pages are now located here.
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2000 CLK430 Cabriolet ~58k Sold
2005 Avalanche 4x4 ~66k
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