car cranks but won't start, some smoke comes out of muffler when attempting to start, battery is fine, not out of diesel, oil level ok, preglow indicator out.

where should I start looking?
is there a service manual for this car?
If so, any ideas on where to find get one?
Is the CD from mercedes shop useful?
what info does it contain?
Thanks in advance
Curtis
Rockville, MD
1986 300 SDL
1990 Allante

Yes, the CD is useful, it is actually a pair of discs for a 126 chassis. It contains everything from the owners manual to wiring diagrams.
The problem is with the pre-glow starting system, more than likely 1 or more glowplug is burned out.
The glow plug relay is in the left front fender well, roughly behind the left headlight. Pull the cover off and see if the strip-fuse is OK. If it is, pull the connector off that has the wires running toward the engine. Using a heavy duty ammeter (0 to 60 amps), plug the ammeter lead into the 5 sockets one at a time and observe the readings. The amp draw should stabilize at about 15 amps after 10 seconds, it will start out higher, then drop after a few seconds. The small numbers on the face of the connector indicate the cylnder number that the socket feeds power to. If you find one or more bad glow plug, you may want to consider replacing them all. If you don't have a means to test the plugs but want to try something on your own, bad glowplugs are pretty common, you could try them first.
Gilly

As for the late 617 engine, if you have only one glow plug is bad, you should still start the car at room temperature but the light will not be on. The smoke from the tailpipe is the raw diesel fuel.

If glow light starts not to work lately and you cannot start the car right after discovering the malfunction light, your problem is likely the 80A fuse or the +12V to the relay box.

If your light has not been working for a while and only now you cannot start the car, it is likely that 2 or more plugs, but not all plugs, go bad.

Good luck

David

[Edited by be459 on 07-09-2001 at 02:29 AM]

Thanks for the help. It was the glowplu relay strip fuse that was shot. Any idea what would cause this or if I should be concerned about it?
Once again, thanks in advance.
Curtis
1986 300 SDL
1990 Cadillac Allante

Very likely to be the fuse and very likely that it will be broken rather than blown. Due to the tremendous current that passes through it, the fuse heats up and expands. It does this during every glow cycle and then contracts after cooling. This cycle fatigues the metal and a crack forms. Eventually it separates.

Replacement is all that is necessary as it takes years for this to reoccur.

I am not sure if the glow plug control electronics for the 300SD and an '82 240D are the same, so this may be of little value to you. My experience with the 240D has been that when the glow plug light does not work and you turn the key to the off position and try it again and it works, you have one glow plug that has gone bad. When you get no response the second time you have two plugs burned out, and the car will generally not start. I have never had to replace the fuse because it was broken or burned out, but I have replaced it just because it looked to be in poor condition (kind of drooping in the middle, and no longer shiny) and it was easy and cheap to do. The glow plugs are also relatively cheap considering how long they typically last. Good Luck!