Frusterated....."Need Help".....
 

OK, I have a 1983 300SD MB..

When I purchased the car, I got a "NEW" 1,000 CRANkING AMPS BATTERY... then it started, If the car did not start after the first few turns= "dead battery".

A.) Took the car back, did battery, alternator "check-up" results=
all ok, just the battery is discharged...so charged battery.

B.) "Same symptoms", after two days...if not start, after first few
tries="dead battery".

C.) Went back demanded "New battery", got a new one
irregardless of test results.

D.) Now guess what? Even though, the tests say alternator,
and battery, is "OK".. The battery "goes dead" after four-to
five turns..

* Note nothing is left on, or draining the battery, to my
knowledge. Checked obvious lights, trunk light etc. I even
take the head off my cd before turning it off.

Help??

KYCOL

KyCol

Your engine demands a lot from a battery when turning over an engine.

I ran into this several years ago when I had diesels. It turned out that the battery wasn't sufficiently charged, something called a surface charge.

I had it charged over night and never had a problem again. What weight oil is in the car? Maybe too heavy for the ambient temps?

Haasman

Check your battery with a good digital voltmeter in the morning before starting. Fully charged, it should read 12.6 - 12.7 Volts. If it is reading around 11.9 - 12.1 Volts, it is almost fully discharged.

Now, if it reads fully charged, and then dies after 5 cranks, I would suspect shorted windings in your starter.

Steve

Probably two things -- insufficient charge from a bad voltage regulator or bad diodes in the allternator (bad diodes will reduce the amps delivered), and a "tired" starter.

When the diesel starters get some age on them, the windings tend to aquire too much internal resistance. This means current won't flow properly, they turn slowly, and draw an amazing amount of current due to slow rotation. Something like 2000 amps or more (noral draw under load is 950 A).

Corroded battery cables will do this too -- no current flow to or from the battery. If you have one or both battery ends replaced with clamp on ends, get new cables, the clamp-on repair ends will corrode horribly, with the result that you don't get decent contact.

Also check the cable connection to the starter -- there are three or four wires there -- the battery cable, the wire from the alternator, the main fused buss for body electrics, and sometimes another wire. Fairly easy to have to slip up into the boot when changing a starter and have it just sitting there, not under the nut.

Peter

Thanks Everyone for the replys
 

Ive disconnected the trunk lite, rear seat courtsey lite, electric antenna and checked doors for humming noises or heat/smoke and none, even all the fuses are cold..

Now, looks like I had better check the battery/alternator..gotta sneaking feeling its the alternator eh?

Thanks

KYCOL

Check to make sure your alternator belt is tight and in good shape. If it is loose or worn, it might be slipping when the alternator is under load (charging). Also check the pulley on the alternator. I had to replace a pulley due to wear, which caused slipping and the destruction of the belt.

You'd mentioned the alternator was working properly. I'm with the starter demanding too much from the battery. Everything is fine until you try to start it. Check voltage at battery after engine is running. Should be at the voltages listed above. That indicates proper voltage from alternator.

starter
 

Had the exact same problem, exact same symptoms, starter would drain the battery in very little time. The starter seemed to crank relatively fast at first, but couldn't sustain it long enough to start on really cold morning. Took my mechanics a bit of time to narrow it down. Replaced the battery and starter finally, and things are golden.

Battery problems
 

If the alternator is charging properly, and the battery is OK, then something must be discharging the battery. Not just starting the car. Even a diesel is designed to start the car without the battery going flat. It must be something unusual.

Put an ammeter on the battery. Not on the starter wire, but on the thin wire. My 190E has a convenient junction block right at the battery. It shuld show initial charging. when you first start the engine, of 30 amps or so.

Then look for a drain when everything is off. Pull fuses until the drain stops. Investigate every component on the bad circuit until you find the problem.

My 190E had a steady 2-amp drain, which sucked the battery down in a day. It turned out to be the electronics in the power antenna. They leaked out and made the circuit board hot and stinky. Now my antenna is unplugged, and my battery is healthy again. I wish I had figured it out before I jumped to the conclusion that my battery was dead, and junked a perfectly good battery.

Trial & Error?
 

Well my MB's in the shop, I'm having the starter replaced in the event its drawing too much .....

I'm also having the valve cover gasket replaced as it has been leaking --Possibly into the starter???

Here goes---

KYCOL

FIXED!!!
 

Well it was oil leaking from a valve cover gasket down on the starter causing it to drag/ go bad....replaced valve cover gasket, starter and "BINGO"

No little black spots

No starter problems

Thanks Guys!

KYCOL