Hey all,

I'm quite active on benzworld and thought I'd take a stroll over here, this diesel forum seems a bit more complete than the W124 forum over there.. Anywho:


I just got my 1987 300D, with the 3.0 turbodiesel engine. Is that an OM603? How many valves, and can anyone give me some specs on the engine? HP/TQ?

On these cars, if the alternator or voltage regulator craps out on ya, is it normal for the idle to drop significantly? I jumped the car and as the battery was charging from the jumper cables, the idle grew significantly, back to almost normal.

Could anyone tell me what's ailing my oil burner? When I have the driver door closed, the windscreen wiper wont work, the power seats dont work, the power windows wont work, pretty much anything electrically powered in the cabin don't work when the driver door is closed- however OPEN, everything functions as it should.


Could anyone help me out with those three matters? (Still workin' on pictures of the beast, btw..) It would really be a big help if anyone could provide a little insight into my problem.



>C-MINE

Welcome.
OM603 is your engine, the 6cyl turbodiesel with 2valves/cyl., I believe it is 188hp but not completely sure, hydraulic valve adjusters.

Without 12v the engine will run normally, but won't idle normally, it will drop to the mechanical stop around 600rpm, with proper 12v the idle is electronically controlled. If the tachometer doesn't work and it idles low it is probably the overvotage protection relay behind the battery, fuse.

The door open thing? Don't really know.

Should be a fairly fast car also, 0-55 is about 8.3seconds factory so if it's a slug we can help you.

__________________

Gone to the dark side

- Jeff

About the electrical difficulties you are experiencing...

Bear in mind that for the most part, each of those components you have mentioned - windows, wiper, and so on, are energized by several different cicuits. As an example, Fuse "G" protects the front window circuit while fuse "H" would protect the rear window circuit; fuse number "2" protects the wiper system, and so on.

On the 1990 through 1992, a convenience control module is located under the rear seat on the left side. Granted, your 124 is an '87. So, for '87, two relays ((not fuses) (position "F" and position "H" )) are found in the "component compartment." This is what appears to be a box measuring roughly 4" X 6" and is directly aft of the fuse box under the hood on the left of the car. Convenience relay "H" is in the circuit that powers-up turn signals/hazards, the heated rear window, and the wiper motor. Convenience relay "F" is the relay for both front as well as rear windows. Looking at the relays (once the lid has been removed by backing out the six retaining screws), you will see three columns. "F" is in the center column, toward the firewall and "H" is in the center column toward the nose of the car.

That said, and really more to help you determine where these items are for troubleshooting purposes, I believe also, that interior lighting is handled via Convenience relay "H" and here's my guess: If the car is new to you and its history is unknown to you, I would certainly begin with a test of the fuses as well as the relays mentioned (checking all would be wise, too). With the driver's door open, remove the jamb switch. If I recall, the factory installed alarm system was an available option. I would want to know if someone previous to you had removed the jamb switch in order to power-up an aftermarket accessory of some sort - including an aftermarket alarm that has not only gone south but seems possible that it's taking other vehicle systems (lighting, wipers, windows...) with it.

What I am getting at is that you've either got a faulty jamb switch, faulty relay(s), and/or non-standard, non-workmanlike wiring; non-acceptable.

If your car does, in fact have a factory alarm system, you'll know this by seeing two jamb switches in the driver's door jamb; one directly above the other. Unfortunately, I don't know which one is which. I am sure "gsxr" or some of the '87 300D folks who've been around far longer than I will have that answer. If you spot only one switch, I would begin to suspect bogus wiring behind it - especially if the fuses and relays check-out.

The jamb switch is easy to remove and can be carefully pulled away from the jamb with a couple inches of its wiring in order to inspect. Use a good meter to check for Ohms in both the open and closed sides of the switch if at first you don't see what looks like obvious, extra wiring that didn't come from the factory. Temporarily remove the wires from the switch to check for Ohms.

One other area to look is above the driver's legs, behind the black plastic covering panel. Carefully remove that panel and visually inspect every square inch of that area in all its nooks and crannies. You are looking for again, obvious extra wiring that may appear to have been installed at some point after 1987. If you see something, try to make a note of where the wire(s) originate and where they terminate - then make another post here to let everyone know what you've found.

Apologize for then lengthy post but hopefully there's some help in it somewhere.

Oh, and congratulations on finding a really great Mercedes and welcome to MercedesShop!

Tom

Babymog- That answered exactly what I wanted to know and quelled any fear of anything else ailing my idle-issue... Thank you for the information on that and the engine.

Adenauer- First and foremost thank you for the information also. It is a huge help. The door jamb has two door jamb switches- the bottom one when depressed, is what was causing the odd fault in the electrical system (meaning, that switch was the switch when activated that caused the electronics to operate oddly). And I assume the top one is the true, factory installed alarm?

I'm familiar with the fuses and what each correspond to, I replaced all fuses in the main fuse box, even ones looking suspect and the problem is still there. I'm pretty sure I can rule out faulty wiring, as it is indeed the factory alarm with the sticker on the window and two door jamb switches. This leaves me with the relays, or a faulty door jamb switch. I'm leaning towards my relays being the problem- as I don't believe a faulty door jamb switch would randomly allow certain things to not work when the door is shut (chime in if you do think this is a possibility, please).

I'm going to check out the door jamb switch just to be totally sure and then test the aforementioned relays. It may be a few days until I can post any of the results, but I'll keep on this.


Thanks for the help and thanks for the welcome, I'll be here plenty often..


C-Mine

What I meant to say was that if there is any sort of bogus wiring on the back of a switch, that wiring could be shorting to ground inside the jamb or any number of other scenarios. I have seen a car where after having had some stereo installation work accomplished by Circuit City, the car kept experiencing strange symptoms. The hot lead for this aftermarket stereo had no terminal connector on its end. It was simply stripped wire, twisted together - and intermittently shorting inside the console.

A faulty switch wouldn't be the cause of what you are describing. Bogus wiring anywhere in the car, could, potentially be the cause.

That's what I am getting at.

Not quite as powerful as 188 as stated above.

__________________
87 300D 265Kmi
Factory rebuilt crate 603.96x engine at 200K

Thats funny (well maybe not to you), but I just drove a 87 300D that was for sale, and the power seat adjustments and telescoping steering wheel only moved with the door open... must be a wire loose or broken which comes back into connection when the door is open.

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OM603.960 specs...
87 X 84mm bore/stroke
2,996cc (189 cubic inches)
Firing order is 153624
Max engine speed, unloaded is 5,150 rpm
HP 148@4,600rpm (federal) 143@4,600rpm California
Torque 201@2,400 rpm (federal) 195@2,400rpm (California)

I use a jingle to remember the firing order on an L6 from the days i had a Dodge Dart with a 225 slant 6. 15 too young, 36 too old, 24 just right.

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1959 Gravely LI, 1963 Gravely L8, 1973 Gravely C12
1982 380SL
1978 450 SEL 6.9 euro restoration at 63% and climbing
1987 300 D
2005 CDI European Delivery
2006 CDI Handed down to daughter
2007 GL CDI. Wifes