Ouch, Deja vue.
 

"1985 300SD Sady" had the same issue; he was using a ten amp charger, waste of time.
The minimum you need is a fifty amp charger, a one hundred twenty amp charger would be better.

A ten amp charger will take twenty four hours to top off your battery.

"PM", 1985 300SD Sady, if you have any doubt.

A diesel has got to spin pretty fast or it won't start. If yours is going "whump, whump, whump" it's a cinch you have a "tired" starter (meaning the internal resistance is way too high).

The "start" function won't do anything for you -- that starter normally draws 900 A or so on a cold engine, any extra 100 won't do anything for you at all. When they get "tired", the starter can draw upwards of 2000 A! Battery goes flat VERY fast.

Put a paint spot on a fan blade and have someone crank it while you attempt to count how fast the spot goes past. Engine MUST turn at least 100 rpm, so you shouldn't able say "1001" before it goes past again.

My brother's 300D quite starting cold last winter (complete engine rebuild a couple years ago, should start instantly). Cranked REALLY slow, simply refused to start until it warmed up. Finally got him go buy a rebuild (by Bosch) starter, and the difference is simply amazing. Still takes a full minute stone cold on the glow plugs (series), but it starts instantly then.

Peter

its not that bad.
 

I'm patient, and i find that the 10amp is doing ok. I don't plan on charging so many batteries that i have to hurry, this is an occasional, not critical tool. but faster is nicer, i'm with you on that. And i'm still not starting after a full, overnight charge.

I'm using this to recharge the battery over time, not assist with starting!

Can you hear the engine start to slow down after a couple of trys on the starter? If so, I would suggest trying to put a higher Amp charger on the battery while cranking.

This is a problem that I ran into. I bought a new battery (you said you did also) and a charger with a 50Amp setting. Whenever my car doesnt start the first time, I run and get the charger without hesitation.

?block heater?
 

Do you have a block heater installed in your engine?

I'm fuzzy on the exact location of your connection, but look for a male plug
some where on the passenger side of the FRONT after you open the hood.

That would eliminate ,at least for testing, the glow plug concerns.

Diesels are funny about "jump starting" . I've started compression engines
with "BAD" starters by OVER VOLTAGE/OVER AMPERAGE(the difference
between two "Booster" batteries in sequence/parallell)

On the car, an AMP draw measurement as the starter is turning,will tell you
all you need to know. (But , most of us lack the "Hall Effect" clamp to
enable our multimeters to make the measurment [cost] ).

I looked for a block heater thinking it might have one, but couldn't find anything. Should i expect one?

Can you elaborate? Was the second battery more useful in parallel or series? I guess traditional "jump starting" is adding another battery in parallel. Did you have success with "jump starting" in series, using 24v?

Melt down the starter and electrical system
 

under one second with 24V current. :eek: :(

Attached is a drawing of the only SAFE way to add a second battery for more cranking power.
The flaws are added weight and if one goes bad, it can scrap both batteries and the alternator.

Well, i know it runs once it gets started, so i think i'll wait for my new starter to come in the mail rather than mess with 24v. thanks for the help and i'll let y'all know what happens.

While cranking, are you holding the accelerator pedal to the floor? This helps with a cold engine, as the extra fuel assists in starting.

Have you tried having the car towed to start it?
MB Automatics in the W123 series can be tow started.
With the key in the ignition (Acc position should release the steering lock) and the car in neutral, have the car towed to 20MPH. turn switch to the ON position so that glowplugs operate.
When glow lamp goes off, slip transmission into "L" and the engine will turn over.
If it starts easily, the problem is in the starter/barttery. If hard to start, there may be problems with air in fuel, injection timing, fuel quality or other problem.

I am holding accelarator down when cranking.

I have not tried tow starting it. I do know that it runs well from test drive and driving it 60+ miles (and 2000 verticle feet) home on I-25 a week ago. I guess i might try tow starting it to drive it to my friend's shop for new starter install; it would be nice to know that it still runs.

I use my Diesel truck...................that will supply me almost 2,000 cca Two Optima batteries in parrallel. more jiuce than any jump box will give me.

New Starter In!
 

now it starts like a champ. Thanks for the help! I'm sure I'll have lots more questions, but I'm going for a drive right now!

bump
 

Thanks everyone!

You are welcome...
 

Nice to see another happy Mercedes Benz Diesel owner. :)
You must have a something or other eating grin, stretching from here to there right now. :D :D

i guess i'll have to ride on this thread right now..

just had the news arrive.. my alt and starter have gone south at the same time!.. arrgh!.. just when i was saving up for somethign i've really wanted to buy this happens.. :( i guess i'll have to postpone buying that gift for me..:(

question... would a 70AMP rated alternator work fine with my car? my old alternator was rated at 80AMP.. but whenever we test it if it were charging.. it is just holding 12V.. it doesnt even jump up when revved hard to 14V... i've manage to start the car from time to tme..but since both alt and starter is going south.. it is really hard to do that..