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

[Mark Foster]

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!

> W126 SEC Mailing List

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

> 


The MB Coupes Website!
W126 SEC Mailing List
Postings remain property of MB Coupes, L.L.C.
The MB Coupes Website!
W126 SEC Mailing List
Postings remain property of MB Coupes, L.L.C.

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