[W126 Coupe] 1982 380SEC - started but won't stay charged

[Iain Gunn]

Don't assume anything when it comes to automotive electrical. I HAVE seen 
alternators brushes seize up on stored vehicles, batteries going flat and 
loosing cells, corroded connections,etc.
Take the reading and report back. FYI when your charge a good battery with a 
demand type of charger that has an amp gauge, when you first connect, the 
amp gage should read high, then drop down to almost 0, after 24 hours, if it 
stays at high amps, the battery is toast. A battery charged or discharged 
should always read 12 volts. Most batteries have 6, 2 volt cells, if you 
test volts and get 10 volts, viola, 1 bad cell.
If your getting low volts when the engine is running clip your voltmeter 
onto the battery and whack the alternator with a wooden mallet, volts jump 
up, brushes shot, or alternator bad.
----- Original Message ----- 
From: "Mark Foster" <mfoster at fosterfirst.com>
To: "'Mercedes Coupes Mailing Lists'" <mbcoupes at mbcoupes.com>
Sent: Thursday, June 18, 2009 11:22 PM
Subject: Re: [W126 Coupe] 1982 380SEC - started but won't stay charged



> Jay,

>

> The battery was about a year old before the coma set in.

>

> I will check the resting and running voltage and report back.

>

> Any thanks - Jay - Dick & An,

>

> Mark

>

> -----Original Message-----

> From: mbcoupes-bounces at mbcoupes.com [mailto:mbcoupes-bounces at mbcoupes.com]

> On Behalf Of Jay Hirsch

> Sent: June 18, 2009 8:16 PM

> To: Mercedes Coupes Mailing Lists

> Subject: Re: [W126 Coupe] 1982 380SEC - started but won't stay charged

>

> Alternators do not go bad from sitting

> How old was the battery prior to the one year  the car was  in a  coma?

> Buy a  new battery

> Jay H

> On Jun 18, 2009, at 10:59 PM, Dick Spellman wrote:

>

>> Hi Mark,

>>

>> check battery resting voltage (engine off)...check battery voltage

>> with engine running..then report these two readings to list

>>

>> Regards,

>> Dick

>>

>> Mark Foster wrote:

>>> Hi,

>>>

>>> I suspect this is an alternator issue - but I thought I better ask

>>> the

>>> expects in this forum.

>>> My 380 SEC has not been running for about a year. I went out and

>>> started it

>>> today and after a 20 minute jump it started but I had to turn the

>>> key a

>>> number of times as it seemed as though it would not always catch. The

>>> dashboard starting lights would illuminate but there was just a

>>> click sound

>>> and then nothing. So I gave it a few more minutes - tried again -

>>> and this

>>> time it started. I gave it a few minutes running, then shut it off.

>>> Naturally it would not start again ( actually was surprised the

>>> old girl

>>> started for me in the first place) so another jump and the same

>>> scenario -

>>> clicks  - then finally it caught and roared to life. This time I

>>> let it run

>>> for half an hour  - watching all the gauges ( seemed normal ) -

>>> then went

>>> for a very short drive. Up and down my street - just in case ;-)

>>> So I finally turned it off and - guess what? Nothing! The battery

>>> seems fine

>>> as I had it on charge for a few days before attempting this. So, I am

>>> guessing the next natural trouble shooting progression would be the

>>> alternator?

>>> Thoughts/comments greatly appreciated.

>>>

>>> Mark ( Vancouver - Canada )

>>>

>>>

>>>

>>> -----Original Message-----

>>> From: mbcoupes-bounces at mbcoupes.com [mailto:mbcoupes-

>>> bounces at mbcoupes.com]

>>> On Behalf Of kabed1980 at yahoo.com

>>> Sent: June 17, 2009 5:14 PM

>>> To: Mercedes Coupes Mailing Lists

>>> Subject: Re: [W126 Coupe] Suspect OVP relay (update)

>>>

>>> When I finally got to my 560after 7 years of sitting not running I

>>> finally

>>> got to u got it running bitter then new I had the run in with the

>>> alternator

>>> same description Sent via BlackBerry from T-Mobile

>>>

>>> -----Original Message-----

>>> From: "Iain Gunn" <igunn at bmts.com>

>>>

>>> Date: Wed, 17 Jun 2009 19:08:54 To: Mercedes Coupes Mailing

>>> Lists<mbcoupes at mbcoupes.com>

>>> Subject: Re: [W126 Coupe] Suspect OVP relay (update)

>>>

>>>

>>> Here, let me tell you another one that will throw you.

>>> Speedometer starts bouncing all over the place, all gages start

>>> going erratic, everything starts shutting down, blower motor goes

>>> on to high heat.

>>>

>>> Think you're in the "Close Encounters of the Third Kind" movie?

>>>

>>> Brushes in the alternator, or alternator.

>>>

>>> Anyone got more for the new guy?

>>> ----- Original Message ----- From: "Afzaal Khan.M"

>>> <afzaal53 at gmail.com>

>>> To: "Vance Rowley" <vance.rowley at tiscali.co.uk>; "Mercedes Coupes

>>> Mailing Lists" <mbcoupes at mbcoupes.com>

>>> Sent: Tuesday, June 16, 2009 9:04 PM

>>> Subject: Re: [W126 Coupe] Suspect OVP relay (update)

>>>

>>>

>>>

>>>> Great!  fault diagnosed and  rectified.

>>>> mak

>>>>

>>>> On 16/06/2009, Vance Rowley <vance.rowley at tiscali.co.uk> wrote:

>>>>

>>>>> Yes, at last, confirmed. Received my new OVP relay this morning

>>>>> and before

>>>>> the delivery truck had driven away, I had the parcel ripped open

>>>>> and fitted

>>>>> the relay. My thoughts as I was about to turn the ignition key

>>>>> was "well,

>>>>> here goes" But as soon as I did, I could tell that this is it,

>>>>> as the engine

>>>>> started immediately and the ABS/ASR warning lights went out. It

>>>>> used to take

>>>>> around 10 seconds or more of the engine turning over to start

>>>>> with the old

>>>>> relay. The engine was very smooth and no stumble or hesitation

>>>>> when revving

>>>>> the engine. The idle was fine also.

>>>>> I know that the OVP gets blamed for everything, but it looks

>>>>> like if you

>>>>> have the 4 symptoms all at the same time.

>>>>> 1. Takes a long time to start

>>>>> 2. High Idle

>>>>> 3. ABS/ASR warning lights remain on.

>>>>> 4. Rough running of the engine.

>>>>> Then it looks like the problem is almost certainly the OVP

>>>>> relay. Of course

>>>>> it is possible that the fuse is just blown, but if that is OK

>>>>> (as mine was)

>>>>> then a new OVP should be the next step.

>>>>>

>>>>> For those who want to have a go at repairing the relay, from

>>>>> what I have

>>>>> discovered along with input from this group, it looks like if

>>>>> you get all

>>>>> symptoms at the same time, then as long as the fuse, relay coil,

>>>>> contacts

>>>>> and solder joints are OK, then the most likely culprit is the diode

>>>>> connected between pin# 15 and the relay coil. It is unlikely

>>>>> that the zener

>>>>> diode is the problem, as this would more likely blow the fuse if

>>>>> the zener

>>>>> was at fault. If you get only 1 or 2 of the above symptoms, then

>>>>> a solder

>>>>> joint (or more) would be most likely.But of course when you get

>>>>> only 1 or

>>>>>

>>>

>>>

>>>>> 2

>>>>> of the symptoms, say for example the ABS warning light on, then

>>>>> it's

>>>>> possible the OVP is fine and that the problem could be the ABS

>>>>> computer

>>>>> itself. It's understandable that the OVP gets blamed for

>>>>> everything, but is

>>>>> certainly the first thing to check.

>>>>>

>>>>> Thanks again to everyone who gave their input.

>>>>>

>>>>> Regards,

>>>>>

>>>>> Vance.

>>>>> The MB Coupes Website!

>>>>> W126 SEC Mailing List

>>>>> Postings remain property of MB Coupes, L.L.C.

>>>>>

>>>>>

>>>> The MB Coupes Website!

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>>>>

>>>>

>>>

>>> The MB Coupes Website!

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>>> The MB Coupes Website!

>>> W126 SEC Mailing List

>>> Postings remain property of MB Coupes, L.L.C.

>>>

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>> The MB Coupes Website!

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>

> The MB Coupes Website!

> W126 SEC Mailing List

> Postings remain property of MB Coupes, L.L.C.

>

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> Postings remain property of MB Coupes, L.L.C.

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