Strange idle problem: 300SD

[mechmagcn]

I posted this last year but the weather warmed enough for the problem to go away before I could fix it.
On my 82 300SD, when the temp is less than 50* out, the engine will not idle when first started. If you just keep a small amout of pressure on the pedal, it will idle, but as pressure is removed the engine will idle slower until it dies. Let it warm for 2-3 minutes and all is fine. This seems to be a governor issue that only arises when cold. If anyone has an idea, I'm all ears.
P.S. setting the idle higher doesn't seem to help either.
Jeff

[Diesel911]

Originally Posted by mechmagcn

I posted this last year but the weather warmed enough for the problem to go away before I could fix it.
On my 82 300SD, when the temp is less than 50* out, the engine will not idle when first started. If you just keep a small amout of pressure on the pedal, it will idle, but as pressure is removed the engine will idle slower until it dies. Let it warm for 2-3 minutes and all is fine. This seems to be a governor issue that only arises when cold. If anyone has an idea, I'm all ears.
P.S. setting the idle higher doesn't seem to help either.
Jeff

There is a few things that can cause this related to if everthing is not "tuneup" on the car. IP timming, valve adjustment, worn out injectors and so on.
It also might be that you need to increase your idle speed until winter is over.

[mechmagcn]

Originally Posted by Diesel911

There is a few things that can cause this related to if everthing is not "tuneup" on the car. IP timming, valve adjustment, worn out injectors and so on.
It also might be that you need to increase your idle speed until winter is over.

IP timing was checked less than 20K back, as were the valves adjusted. New injectors were put in at the same time because I had them out to repair an issue with the head. If I increase the idle speed to the point where it doesn't die when cold, the car is almost undrivable when warm.
There are no idle issues when the temps are above 50*, just on cool mornings.
Engine has less than 50K on it, but I don't know if the IP was rebuilt at the time of the replacement.
Jeff

[Brian Carlton]

Originally Posted by mechmagcn

This seems to be a governor issue that only arises when cold. If anyone has an idea, I'm all ears.
P.S. setting the idle higher doesn't seem to help either.
Jeff

If you positively set the curb idle speed higher and you can verify that it increased when warm, you should have a similar benefit when cold.

You are correct in that the governor, if working properly, will maintain idle speed.......independent of temperature........within certain parameters.

You're providing fuel through a bunch of springs and flyweights. If the fly weights are not moving inward as the speed slows..........the rack won't open and provide more fuel.

On a properly running 617, you can actually hear the engine increase speed ever so slightly when cold and then governor immediately pulls the speed back. This will happen repeatedly as the engine warms and less fuel is required to maintain idle.

[mechmagcn]

Originally Posted by Brian Carlton

On a properly running 617, you can actually hear the engine increase speed ever so slightly when cold and then governor immediately pulls the speed back. This will happen repeatedly as the engine warms and less fuel is required to maintain idle.

Sometimes after it has been running a minute or so, it will try to idle and when the speed increases as you say, it will fall back and die. This is the second year of trying to figure this one out, I'm almost to the point of changing the IP with one of the spares that I have.
Jeff