1984 mercedes 300SD W126

today out of nowhere my car would not start. i would turn the key and nothing. my battery is good i double checked it. so i thought it might be the gear, because the car would not start in anything other than P or N (right?). so i played with the gear a lil bit with no luck.

now when i turn the key. there is a buzz comming from the box mounted on the driverside fender. i think it is the glow plug relay? when it buzz's does it mean that it is bad? do i need to change the whole thing of just a part of it? what is this box called? i need help thanks for any advices

Yes, that is the glow plug relay.

Does the starter even turn when you turn the key to 'crank' position?

You could pop off the lid from that glo-relay box and check the fuse. Even if its bent, it won't function right.

However, this would not cause the car to go dead like the above post mentioned.

I sometimes have a dead (and I mean dead) experience with my TD. Can't figure it out. I come back in an hour and it works.

Perhaps the ignition switch....?

Don

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DAILY DRIVERS:
'84 300DT 298k (Aubrey's)
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'97 Jetta TDI 127k (Amber's)
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SOLD:
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no, the starter does not crank at all. this car usually starts with the turn of the key even in -6.5C*

so if the fuse went bad. would that cause it to buzz?

oh and one mroe thing. i've noticed when i turn teh key from the "glow plug"" to crank position the lights in the car dims. kinda like how it always does when it starts

if you really need to get it started, just to get it to a mechanic etc, i can tell you how to jump the starter cylinoid. Let me know,
Ryan

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83 300SD.......sold
96 integra SE....sold
99 a4 quattro....sold
2001 IS300.......sold
2002 330i.........current.
2004 highlander limited....current.

i never go to mechanics.. bad experiences.

basically i am trying to figure out what is bad the glow plug relay or the fuse. and what is causing the buzz sound when i have the key in the "glow" lock. or what does the buzzing mean. i am thinking of jump starting and see if there is any difference.

problem half way solved. jumped start the car and it started right up. now i am looking to the charging system. thxs for all the advices.

Ned,
Lights dimming is either a bad battery or you may have a bad ground cable. Check all teh connections as this may be the cause and is a lot cheaper than a new battery.

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'99 S420 - Mommies
'72 280SE 4.5 - looking to breathe life into it
'84 300SD Grey - Sold
'85 300SD Silver - Sold
'78 Ski Nautique

Unless you have replaced your fuzes in the last year or so, I would recomend that you do so. More then once I have thought that I had a problem which would require repair but by following this piece of advice I have ended up saving time and money.

A good test that will "divide and conquer" your problem between the battery and its connections, or something else:

Turn on the headlights, either under conditions where you can see them or have a helper watch them. Now try to crank the car. If the headlights go just about out, its the battery or a bad cable connection. You can try jumping the car with jumper cables, or removing the cables and cleaning their connecting surfaces. And, as Fisherman comments - it could be your battery ground cable connection at the chassis.

If the headlights stay fairly bright, then you have some kind of issue with the starter or solenoid. The starting system is not drawing current.

At least that's where the probabilities fall for this test.

What test did you use to double check your battery?

Ken300D

I had this exact problem with my 300D at Christimas time. I drove from Houston to the panhandle of Florida. Once I arrived at my destination and unloaded the car, I went to back my car out of the drive and experienced the exact symptoms you described. I thought at first it was the GP relay...no dice. It turned out to be the alternator. I ordered a new one, installed it, and have had no problems since.

The beauty of these cars is that the engine will keep right on running even after you have killed the battery and the alternator is dead. You may not have headlights or a radio any longer, but at least the engine still runs. (unlike a GAS engine!!!)

Mike

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Mike

'80 300D
'84 300D
'85 300D
'87 300D

Put the car in neutral and try to start it. A no start symptom can be caused by a faulty neutral safety switch among other things.

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Regards,
Aaron

wow thxs for the replies. i will have to try the test you have mentioned ken300D. right now i am suspecting the battery. i think it is not keeping charge. today i had to jump start it in the morning. but then i started fine all day. i will have to see tomorrow.

sublettm: this is my second concern. i am having second thoughts on wether my charging system is working fine or not. i put a multimeter to the battery when the car was running it had around12.5 volts. and when i gave it gas it jumped to 13.3 volts, this was yesterday. so i thought that it was fine, but this morning i bought one of those cigarett plug in things that check your battery/charging system and according to that it says my charging system is running "low" i don't know wether to trust the multimeter or that thing, and boy i hope it is not the alternator. is there any other way to check if the alternator is working properly?

sounds like a lot of troubleshooting for me. but for now i just carry a charged battery around. thxs again for all the help

I don't know of any way to check the alternator without pulling it out of the car. It really isn't a difficult task to pull one out...relatively speaking. Once you get it out, run it up to AutoZone and they will check it out for free. A replacement isn't that expensive. I got a rebuilt Bosch for about 150.00 if I remember correctly. Do you know if the alternator has ever been replaced? Mine was origianl to the car. Some of the other guys on this site have also replaced the brushes and the voltage regulators as opposed to replacing the whole thing. That is a less expensive option if you know how to do it. I probably would have gone this route but I was out of town and didn't have time to mess with it.

Some of the other replies to your message were good suggestions, but I am putting money on the alternator. The symtoms you described were exactly like mine.

Mike

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Mike

'80 300D
'84 300D
'85 300D
'87 300D

The brushes as well as the voltage reg on my 1990 300D 2.5 Turbo can be replaced without removing it from the car. You do need a lift to do it comfortably, though.

I say this because I have seen it done. that was two years ago.

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Semibodacious Transmogrifications a Specialty

1990 300D 2.5 Turbo sedan 171K (Rudolf)
1985 300D Turbo TD Wagon 219K (Remuda)

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