82 300SD Won't idle when cold
 

Hi all, I haven't been around in a while, these cars are so dependable I don't need to work on it.
Since the weather has been getting cooler, I have noticed a problem with the 82 300SD. When first started, it will not idle. If you slowly let off of the accelerator pedal, it will idle all the way down until it stalls. If you just keep your foot on the pedal(with no noticable pressure) it will stay running. It's almost as if the stop diaphram is still pulling on the rack until it warms slightly. Any ideas of where to check first?
Thanks in advance for any help, Jeff

*Bump*
Come on now, someone has to have an idea! The little lady is getting a little bent out of shape when it won't idle so she can run back in the house while it warms up.
Jeff

Does the car start right up or is it tough to start. You may have a bad glowplug, which would make it stumble and run rough untill the cylinder with the bad GP gets up to temp.
A couple of other things you might check. What is your idle set to. Maybe it neeeds to be bumped up a bit. Also check your rack damper bolt. Its on the rear of the injection pump, in the space next to the oil filter housing. Pull it completely out and press on the pin on the end and see if it is stiff(hard to push in) or soft (easy to push in). If it's soft you need a new one. If it is stiff you may need adjust it a bit. Usually a bad rack damper bolt results in rpms hunting when the car is cold. The rpm cycles up and down.
You might also try adusting your valves. They may be tight which would make things tougher to run when cold.

How is the timing chain wear?

Very little if any chain wear, engine only has 42K on it. Idle is fine after it warms up. Valves were adjusted about 8K previous, pump timing was checked at the same time.
Engine starts right up with no miss or stumble indicating bad glow plugs(and we've had some mornings in the low 20's), it just will not idle until it warms for about 2 minutes. It doesn't shake like the damper pin is weak, but does hunt up and down at idle(sort of sounds like my old Detroit when the buffer screw needs tweaking), it does this even when warm.
Jeff

Something I read about...........
 

I recall reading a while back about an idle problem where the linkage was adjusted too tight and was placing the rack nearly in shut-off. Try removing the IP rod from the upper linkage and feel for a detent, then see if it matches up with the linkage. A turn may be all it takes.;)

OK, haven't had time to check out much of the idle problem, but this AM at 17* the SD failed to start for the first time. Went through 2 glow cycles and it only whirled and smoked, glowed 3 times and it would hit and miss and then die. After this the glow plug light wouldn't even come on. Finally got it to start and sent the little lady on her way, but I have to do something this weekend. Guess I start with the glow plug main fuse and then check the glow plugs, any other suggestions while I'm there?
Jeff

I have the exact same problem on my '84 300D. I never figured it out, tried everything (rack damper bolt, glow plugs, valve adjustment, timing chain, tank screen, fuel filters, etc.). I installed a block heater from Fastlane, now it starts right up and stays running.

The more I hear about the symptoms, the more I lean towards the possibilities of what Andrew mentioned with the rack dampner screw.

From what I've seen, if the dampner is too loose, then you get the shaking ....... as in the rack is too close to cut-off. If the dampner is too tight, then you get hard starting, and poor idle till warm, as it is getting too much fuel for a cold engine situation.

However, weak/failed glow plugs would override this as even with a well adjusted rack dampner, you will have a hard, if not near impossible, time starting in cold weather.

I would start with the glow plugs and ensure everything seems to be working there and then try backing off the rack dampner screw about a turn and see if that helps.

You are not running that home-made grease fuel, are you?
 

I know some here say that stuff will jell up at 40 degrees and will freeze at 32 degrees and below. Anyway, I would bet your fuel, whatever it is, is too thick to flow. Either that or you have a bad glow plug system or even worse, low engine compression. You might have to use the electric plug in and get a higher grade diesel fuel and mix that with some kerosene. Some here on this site said they have had good results mixing with gas. But I think that was in the summer. If all else fail, I would just work with the car until it wants to continue running and allow enough time for the fuel to heat before I pulled it out of the yard.

BenzDiesel

Ok, had time this afternoon to look at it. Found 3 bad glow plugs, don't know how it was starting in 22-23* weather as good as it was. This was the first time it has ever failed to start right away.
On to the idle problem, back when this first started with the first cool weather I changed fuel filters and it helped somewhat. While under the hood today, I noticed that it was leaking fuel around the bolt on the secondary fuel filter. Could it be the fuel draining back overnight and a small amount of air in the system causing the idle problem? Will be able to tell more in the AM when the forecast is for 20* again. I mentioned before about it hunting at idle, that also seemed to be helped by the fuel filter change for a while.
I'll report back in the AM with more results, Jeff

No WVO here, using only #2 diesel from the largest truck stop around here which happens to be just a mile up the road.
My other half drives this car, she's the type to fire up and go, drive it like you stole it. When it doesn't run, I catch it. A lot of the time, I'm gone before she leaves for work, so there's no way for me to start it for her.
Jeff

Fix the glow plugs and stop the leak and you should be ok.
 

And if you do find that your compression is a little low for the colder temp. quick starting, then you still can thin the fuel with kerosene or something else that will help the fuel flow better and ignite quicker. But if you found three bad glow plugs, I would bet that was your main problem. The fuel leak contributed as well.

BenzDiesel

My neighbor had the same problem in a E300D and he never bothered to adjust the valves! Adjusting them did help, but now compression is low and the car failed a leakdown test!!! Needs a valve job!!:book:

Just curious ... why does the 602 in the E300D need valve adjustments, but not the 603? Since the E300D was a later model, wouldn't they want to use the adjustment-free technology? Was is it exactly about the 603 that kills the need for adjustments? Sorry to hijack the thread ... I'm just a habitual question-asker.:)