1983 300SD low idle problem on cold start

Kent,

On the rather rare cold morning here in Texas my 1983 300SD will start without any problem. However I have to keep my foot on the accelerator for a few minutes or it will idle down and die as soon as I take the foot off. If I remember to plug the engine heater in at night - no problem at all.

Any suggestions?

Thank you
Dieter

Forums

Diesel Engine Specific Aid

Could be any one of a number of things

Hi Dieter, this is going to require some detective work on your part. This problem could be one or any combination of a dozen or more issues related to engine mechanical or fuel delivery. Give me an idea of all the inspection, testing and maintenance you have done on the engine in the past year - beginning with cold cranking compression numbers.

84 300TD in the same boat

Cold morning are rare here in Austin as we have a very short winter... My 300TD has been in the exact condition as Dieter's the last week or so. It's been in the 40s-50s in the AM. Most of us aren't used to dealing with the same issues as our Northern brethren.

RPMs drop below 500 and it starts to die. If I let it warm up just a little and start driving, it's fine. Idle RPM when warm is around 600-650. Shouldn't it be more towards 750?

1983 300SD Low Idle on Cold Starts

Kent,
Sorry for the delay in replying to your comment,crazy days.
I was not able to do the compression test, I do not have the tools - yet. Here is some background which should help narrow the problem down: The 300SD is now at 339,442 miles, I purchased the car in 03 with 293,300 miles. In 1993 at 203,572 miles the engine was completely rebuilt by Black Frest Motors in Indianapolis, I have all of the paperwork.The curious thing is that the Crank Gear, 3 parts called "Time Chain Rail" and Tensioner was replaced but not the timing chain itself. I ran all of the part numbers and took the itemized invoice to the shop which repairs and services the fleet of trucks of the company I work for, to make sure that I did not overlook anything or that a different description was used - no actual timing chain.
I had checked for chain stretch shortly after I got the car, unfortunately I do not remember the number, they were in the ok range of the info I had at the time but I believe borderline for your recommendation.
Some other info that might be relevant, is that I replaced the injector nozzles with Bosio nozzles at 319,000 miles. I had read somewhere at the time that they were "much" better than those made by Bosch.I had the injectors balanced by a local Bosch place before installing. At the same time I replaced the fuel injection pump with one rebuilt by Piedmont. Since I was worried about timing the pump, I had it done by a local MB knowledgeable tech who has since left town.
At 312,000 miles I had replaced the glow plugs and relay with one of those updated relays by Bosch. I replaced the glow plugs but not the relay with your Monarch plugs at 334,000 miles. I also noticed that the car starts better if I let it pre-glow twice before cranking the engine.Bad relay?
I have your booklet about troubleshooting the diesel engine etc, the correct title escapes me at this moment.
This is the same vehicle where I replaced the whole rear-end with one from a 91 420SEL and had the problem that the speedometer was way off. I fixed that problem by installing a speedometer from a 420SEL. I had its accuracy "certified" by a Texas State trooper, I was doing 80 and he claimed that he clocked me at 79 - too bad that he charged $180 for his unsolicited services.