280 SL 1969 Starting Problems

[Rolf-Dieter ✝︎]

The question; is it the the battery, alternator, starter or the voltage regulator after incorrectly use of jumper cables having been crossed resulting in sparks flying?

BACKROUND

My battery is about 3 years old. The alternator has not been touched nor has the starter or voltage regulator in the 9 plus years that I own the car. A few months ago I took my 280SL on a shopping trip, unfortunately I left the lights on and was a result the car would not start. A friendly shopper offered to help, unfortunately he crossed the jumper cables and it resulted in flying sparks.

Ever since the above incident not having driven the car for a month or so I needed to get the car started with jumper cables. Once started I drove the car long enough to allow the battery to recharge so the car would start okay without external help. On the last three occasions having jumped the car to start and driven her long enough to start unfortunately after driving the car and parking in the garage the car would not start.

The car is difficult to handle after it was started with jumper cables the idle speed on the speedometer shows around 1,200 rpm and does not reduce during the drive. is the voyage regulator causing this?

One more item to note is that once the car stats and I drive her the headlights do work fine, does that mean the alternator is okay?

Being more mechanical than electrical I need some help to resolve this. I am thinking it might be the alternator that is the culprit, however, I am not sure.

What do you think?

If I take the car (naturally using jumper cables), to an electrical shop can the check and positively identify if it is the battery, alternator, starter or the voltage regulator?

Input from the Group is very much appreciated.

Dieter

[BobH]

Hello Dieter

I'm no expert but i would have thought if the alternator had failed the red charge light on the dash would be on all of the time.  it could be that the battery was damaged when the leads were reversed, and now won't hold a charge, a garage or battery supplier can test the battery to see if it's healthy. Low battery voltage may cause other faults, best check the battery first and go from there

A similar story on the post below, not sure of the outcome of that one

https://www.sl113.org/forums/index.php?topic=34175.msg250035

[lpeterssen]

Dear Dieter

The condition of battery, alternator or voltage regulator has no relationship with the high RPM you describe at IDDLE.  These old cars didn’t have a way to increase engine running RPM if battery voltage was low.

RPM IDDLE setting is governed by the warm up device at the top of the mechanical injection pump.

Regarding your concerns related to battery, alternator or voltage regulator condition buy in AMAZON a simple tester called BATTERY TESTER.  I will post a link to one of them.  That is a simple device that you hook to your battery ends, and you select on the menu the size of your battery in Cranking Amperes, CCA, the type of battery Lead acid, gel, etc and it runs a test to see how it is.  Normally such devices also check the condition of the charging system (alternator+voltage regulator).

Maybe, but I am not sure your voltage regulator suffered in some extend.

Link will be posted in a separated message.

Best regards
L.peterssen

[lpeterssen]

Here the link for a battery tester

LNEX Probador de batería de coche, pantalla LCD a color de 2.8 pulgadas, 100-2000CCA comprobador de carga de batería de 12 V, sistema de arranque y carga digital analizador de batería para coche, camión, motocicleta, ATV, SUV, barco, yate https://a.co/d/9pMODHo

[Pinder]

Check that the vaccum line to the distributor is still connected. Maybe during jumping the car a line got pulled. do you have an updated 123 ignition system?

[Cees Klumper]

I'm no electrical expert like Mr Peterssen, but here's what I would do (in addition to following his advice).
Once the engine is running, it's very easy to check the alternator and voltage regulator, by hooking up a multitester that can measure voltage (every garage will have at least one of these, I think I have 4 lying around. They can be had for $15-25 online I think).
When you put the corresponding probes on the + and - of the battery you should get something in the range of 13-14 volts, this means the battery is being charged properly.
With the battery at rest, a couple of hours after shutting off the car (or next morning before starting the car), the same measurement should be at least 12.4-12.8 volts - this will tell you the battery is holding the charge.
Once a conventional battery has been left fully depleted for some period of time, it may no longer work properly and needs to be replaced.

[Rolf-Dieter ✝︎]

I like two thank everyone for there thoughts and suggestions, I shall deal with this issue next week and will report back what Find.

You all have a nice weekend and stay safe!

Dieter

[Rolf-Dieter ✝︎]

Problem solved, after several tests it became obvious that it was the battery needing ri be replaced. So, that is what I did and all is well after that.

Last weekend I took a 600 KM trip to the northern tip of Ontario to the Concourse d'Elegance at Cobble Beach Ontario. I shall share photos soon.

Once again thank you to one and all.

Dieter