Mercedes-Benz Forum banner

1 - 4 of 4 Posts

·
Registered
Joined
·
4 Posts
Discussion Starter #1
Greetings,

I have a 1985 300D with 163K miles. When I first start the car on a cold morning, the idyll speed fluctuates-- goes up and down. As it warms up it stabilizes. It only seems to happen when the outside temp. is cold. Other than that, the car seems to run strong. I know that I have some vacuum leaks to contend with, but I don't know if this would cause the idyll problem. Any thoughts on what could cause this?

Many thanks,
Jeff
 

·
Registered
1984 300D
Joined
·
5,026 Posts
On mine up front by the Crossmember in front of the Radiator is an Emission Sticker that has the normal idle range that the Engine should run at. See if you idles speed is set too low.

You can do a quick check of your Glow Plug with a Volt/Ohm Meter (Multimeter) by following the pictorial on the Dieselgiant web site.

However, that is not the definative Glow Plug test.
Removing the Glow Plugs and testing them with you Jumper Cables to actually watch them heat up is a better test.
Good ones heat up at the tip of the Glow Plug first and stay hottest at the tip.

With the Glow Plugs out the Carbon should be cleaned out of the Glow Plug Holes with a Glow Plug Reamer or some alternative method.
Some have said that reaming the Carbon out also made starting easier.

If your Engine still has the original stock Injectors in it the Injector Nozzles have 2 tiny passages drilled into the Pintel tip. On my Car and most of the Injectors I have pulled from the Junk Yard I have found those passages to be Plugged solid with Carbon.
You idle fuel is supposed to squirt out through those passages.See the pic #14 and #15 are the passages.
Doing a Diesel Purge may or maynot help.


Not particular to your problem but members have said that switching to Synthetic Oil makes cold start Cranking easier.
 

Attachments

·
Registered
Joined
·
4 Posts
Discussion Starter #3
Thank you for the suggestions, I will look into each one of them. I suspect that my idyll might be a little low, it's running about 700 rpm according to my tachometer. I'll post my findings sometime over the next couple of days. Thanks again, I appreciate the pics also.
 

·
Registered
Joined
·
4 Posts
Discussion Starter #4
Well, the problem seems to have disappeared. :confused: I adjusted the idle slightly. I'll keep an eye on it.
 
1 - 4 of 4 Posts
Top