recently began having some issues starting. haven't had a no start yet, but cranking is getting real slow. i thought it might be the battery, took it to autozone and the worker said it was "70% charged but good." this is after driving there for 10 min at a steady 30mph and no acc on at all. they said they couldnt test the alt because it wasn't 100%. she suggested letting it idle for 5 min to charge it, but i dont think the worker understood that would be no different than driving it there since its a diesel and used zero battery on the way there.

my voltmeter gives the following readings:

at rest: 12.2V
glowing: 11.3V
right after glowing: 11.95V
starting: varies, low as 9V to high 10s
idle: 13.14V after starting... then after running for about 5 min 14.2V

battery is MB , 3 years old, alt is reman bosch 5 years old, starter is reman bosch about 2 months old... new ground strap, all connections cleaned

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1981 NA 300D 310k miles

WHO did the Alleged ReMan Job(s) on the Starter and Alternator?

Generally(UNfortunately) here in CONUS "Remanufactured" BOSCH means
"Spray and Pray"
[I.E. Clean the Bugger up EXTERNALLY and repaint,somewhere south of Matamoros]

ESPECIALLY if the remans come from any of the "Big Box" Stores.
[I.E. Pep Boys,Autozone,Advance,O'reilly's,Rock Auto,Etc.,Etc.,Etc.]

At your Mileage The Starter could enjoy:
Interior Cleaning
New Bushings(Bearings)
New Brush holders and Brushes
Mayhaps a New "Bendix"
Etc,Etc.

A Superior,Local,Hands On Re-Builder IS ALWAYS better choice than the
Alleged "Reman" from the "Big Boxes".

If YOU don't feel comfortable Rebuilding your own!

It's Possible to get 500K miles out of a properly Maintained Starter!
BUT,It does require internal replacement and cleaning !

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'84 300SD sold
124.128

at rest: 12.2V is slighly too low. 12.50 is normal and some Batteries will get 12.75

You need to have 11-11.5 Volts when you are cranking the Starter. Also note that while you are Cranking your Glow Plugs are also on.

So either your Battery is on the way out or you have something causing an unusual load.
I am going with the Battery being shot because you said you got 11.3 Volts with the Glow Plugs but the Mercedes Service Manual has that it should drop to 11.5 Volts.

On day on My Volvo Diesel I got 2 normal starts. I stopped to get something to eat and went to start and got nothing.
My Battery Voltage showed 12.50 Volts.
When I applied a Jumper Wire to the Starter Solenoid I only got a tiny spark. My concousion was there was some internal damage to the Battery Plates not giving me amperate.
I walked across the Street to an Autozone and bought another Battery and with that the Car Started right up.

When a Battery load test is done the Battery has to be charged up fully before you start.

When I tested My Cranking Amperage with an Automotive Induction Amp Meter I got about 155 amps.
So if their Battery load tester can do it have them set it at 150 amps. Kind of picture in your mind the amount of time you used to crank before the issue and have them turn the tester on for that amount of time and see how far the Battery Voltage drops.
I know mine starts within 5 seconds after I switch from the Glow Plugs to start and I think 3 seconds is normal for mine to start here in S. California.

Cold weather is another factor that is hard on Batteries.

Higher then normal Battery charging voltage can also be an indicator of a bad Battery. A good Battery has a certain mount of resistance to being Changed.

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84 300D, 82 Volvo 244Gl Diesel

Check the level of the Electrolyte (Acid/Water Mix,in each cell)
Put the Battery on a Low (2 amps,or less if possible)on an Automatic Charger
(This will bring the Battery's cells up to their maximum possible level.)
until the charger shows charged. [At least 12 hours,preferably 24]
Then,taking an inexpensive squeeze bulb acid tester,check the specific gravity
of each cell.
This is the really accurate method of testing the health of the battery.

____________________________________________________________________________________________________ __

Unless,Of Course, It's an AGM (Sealed ,Gel/Glass mat lead acid Battery.

____________________________________________________________________________________________________

ALSO,any advance auto will hook up their Black Box for free @ the curb,
which should show you what the Amp Draw of the Starter is.
Amperage draw rates tell us all we need to know about the health of Starters

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'84 300SD sold
124.128

the starter is i'm assuming, a reman bosch. it is only a couple months old, i'm assuming it comes from worldpac it was installed while i had the car in for some other service. autozone wouldn't test anything other than the battery charge . theres no advanced auto here. maybe i'll take it to oreilly tomorrow. i'll see if i can get them to set their equipment to 150 amps. not sure if the worker at autozone knew what it takes to start a diesel.

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1981 NA 300D 310k miles

Sounds like perhaps a bad cell in the battery. Anyways before spending money charge the battery long enough to get a full charge. Let its sit for five minutes.

Personally I would like to see 12.6-12.75 volts. You want to have one battery terminal disconnected when charging and reading the voltage. Much less voltage wise and you have a shorted cell.

Do you do a lot of short trips? Back in the 80's my dad had an issue with the battery not getting fully charged. We lived less than a mile from where he worked, so he would start the car, drive a short few minutes to work, then shut it down, then start it up again, drive it another few short minutes to work and shut down again. The grocery store and the library were also very close. After he started having problems, he used to take the car out for a longer drive once a week or so and all was good.

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Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 400,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 22,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.

I think its a bad cell too, but i'm just guessing. the battery is 3 years old and i wonder if the previous malfunctioning starter could have done something to kill a cell.

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1981 NA 300D 310k miles

I doubt the starter caused the issue, unless you severely discharged it and didn't recharge it right away. The biggest cause of a dead cell is loss of electrolyte. Loss of electrolyte can be caused by high internal resistance, in that cell, which causes it to get hot during recharge. Overcharging for too long, or too high of a rate, can cause it as well.

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Sam

84 300SD 350K+ miles ( Blue Belle )

Remove the battery and drop it off at oreillys for a test and charge...that will tell you if it is good...

Your battery cables may also be bad, pick up some 2 gauge universal ones from oreillys too...

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I has similar problem. You have to be sure the glow plugs aren't pulling the voltage down. Disconnect the glow system and measure voltage at idle at the battery. Don't assu/me the plugs are off just because it is warm or you drove 10 minutes or whatever.

I had an Autozoo worker condemn the alternator when the problem was the glow box. Even then, you may only need a voltage regulator. I've had Bosch regulators bad ut of the box.

Clean connection and good wiring caveat applies also.

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85SD 240K & stopped counting painted, putting bac together. 84SD 180,000. sold to a neighbor and member here but I forget his handle. The 84 is much improved from when I had it. 85TD beginning to repair to DD status. Lots of stuff to do.

I forget what is obvious to mention sometimes. Can you turn the alternator pulley fins with your hand? If so the alternator belt is too loose. Still at idle you will see 13.5 volts. But when the alternator has to deliver the charging current needed to charge the battery it is not there. So the sitting voltage and charge state of the battery remains low.

well oreilly said the same thing as AZ, the battery is only 70% charged but still good, that is after me driving around for like 30 min before stopping there. worker said the alternator is fine, it failed a voltage reg check on startup but then passed it the next two times. that makes sense to me because i know the alt on these needs rpm to start charging

maybe something is up with this rebuilt starter. maybe its drawing too much power? i still dont like that the battery maxes out at 70%

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1981 NA 300D 310k miles

went out today after letting it sit overnight and it was at 11.95V. i think theres something wrong with the battery.

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1981 NA 300D 310k miles

The car does not need rpms to start charging unless there is a circuit malfunction

Voltage drop overnight points to excessive drain with ignition off... Get an amp reading of off usage.

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
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1987 300TD
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