A very sad day (alternator)
 

Last Monday I took my car (560SEL) in to my local shop because the day before I saw my battery light flicker. The tech said that there was a vacuum hose missing that was keeping my idle too low, and that my alternator and battery tested fine. When I started my car this morning the battery light flickered for a few seconds then went out. When I left work this evening the light was flickering again, and after about 1 mile the ABS light came on. A few seconds later my headlights/dash lights/etc all went out, acceleration was jerky , but still there for a while. A few seconds later the car died altogether, since I was on a blind curve on the highway I had to coast about a 1/4 mile until I could safely stop. I had the car towed to my mechanic, and I'll have it taken care of on Monday (what a fun wekend I'll have!). Is there any chance that other damage was caused by this situation?
Justin

Probably not. As your available voltage deteriorated, the engine management systems were unable to do their jobs, thus the escalating failure of components (and subsequent indicators on the dashboard lighting up). I had an 86 Cavalier that had a dying alternator, and the result was pretty similar to yours...had a heck of a time limping it to my mechanic's shop for service as one by one, major electrical components would fail.

I am awaiting an alternator from FastLane right now for my 300E. I have an opposite issue to deal with which is overcharging (failed regulator). That is more prone to damage since too much current can harm the sensitive components of the engine management system. I believe there isn't any permanent damage right now, but the excess current caused the battery to vent sulphuric acid excessively, so I will have to check the condition of the battery after I install the new alternator.

Make sure your mechanic checks the condition of yours as well.

I am glad the tech found the vacuum hose problem for you but I wonder how well he checked the electrical charging system?was the alternater puting out maybe 12.5 volts and he thinks thats ok ?

he said that it tested at 14 volts, if the problem was intermitent, that would make sense. I have never had any problems with this shop, actually, they have almost always surprised me with their service/honesty. I think that this was just bad luck/timing for me.
justin

Justin, the symptoms you described are tell-tale signs of an alternator failure. The vacuum hose is another problem. Have you mechanic replace the alternator and I know your problems will go away. A friend had two 126s do the same things your did and both times the alternator was broken.

Actually, I'm much less worried about the cost of a new alternator than the possibility of transmission damage. I know that with rear-wheel drive cars you should tow with a flatbed tow truck (which it was) but wouldn't letting the car coast after the engine had shut down cause the same type of damage? That is what really worries me...
Justin

I'll bet you could coast down a fifty mile grade with out damage to your tranny ,might heat the brakes up a touch.....
William rogers.....

Good to know...thanks for all the advice-I just hope all goes smoothly tomorrow!
justin

According to the owners manual my SD can be pull or coast started at 30 mph which would suggest a rear pump in the transmission which in turn should mean that internal pressure is maintained with the engine off and the rear wheels turning.If that is the case then short distance flat towing or coasting at moderate speed should do no damage...
William Rogers....

Well, good news...
The alternator was fine, there was a wire from the alternator that had come loose...total cost of repair-$18.00. Although the situation was rather inconvienent, it couldn't have ended better. Thanks again to everyone for all the advice.
Justin