'89 300TE with 215,000 miles on it. For the last 8 months or so the car will spontaneously stall. This happens about once a week, but has happened as often as twice in a half hour. It usually happens while at speed; the engine simply stops. On the rare occasion it happens not at speed, it happens while coming to a stop, usually just before the actual stop is effected. The cure is to pull over, wait 30-120 seconds and re-start the car.

The most recent time this happened, the first thing I noticed was that the radio went dead. I don't know if this is related, but it went dead at the moment I hit the switch to roll down the window. About 1 minute after the radio went dead, the engine stopped. I rolled onto the shoulder and waited the usual time. This time however, when I turned the ignition, I got the usual power signs (dash lights, buzzing etc...) but the engine did not turn over. I tried a few more times and had the same result except that half the time the radio came on and half the time it did not (my gut tells me this is not a radio problem however). I opened the hood to look for a loose battery cable. After poking around and finding nothing, I went to the passenger's side and opened the back door. Either near the time I opened that door or closed it, the factory alarm went on. I grabbed the keys and locked and unlocked the doors and turned over the ignition. Nothing would shut off the alarm. On my way to disconnect the battery cable, the alarm shut off. Then, 1 minute later, it started back up. The alarm cycled like this until I got a wrench and disconnected the battery. When I reattached the cable the alarm started again.

I called for a ride, waited 25 minutes, and tried one more time. The alarm did not go off and the car started. Then the alarm went off. I started driving down the road, went 2 miles, and the car died again (in a perfect place to coast into a Park-and-Ride; sometimes the car Gods love you!) I ended up towing it the last 4 miles home.

What is wrong and how do I fix it? By the way, thanks to all of you for your help over the last two years.

Sounds like a battery voltage problem. This does not necessarily mean the battery is the problem. There are numerous connections necessary to get the battery hooked to the systems involved.

Because of the diversity of systems involved it would be likely that the problem if not the battery would be close, in the primary power distribution ciruitry - battery cables, alternator harness, accessory leads to inside.

The alternator could have been involved with depleting your battery but has no part in the current situation. Without a voltmeter to trace the drop, one might wish to try another battery.

__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

Is it at all possible that this could relate to the regulator or alternator?

Hans

I guess you must be asking someone else as I clearly stated that it was not your current problem.

There is absolutely no need for an alternator to start a car, it plays no part. Once started you need the alternator to replenish the power used from the battery.

Your problem sounds like a lack of battery voltage where it is needed. That is my answer to your immediate problem. Another battery is a diagnostic concept if you do not have a voltmeter or understand how to use it to verify the voltage necessary.

Your problem is consistant with a large voltage drop. That can happen two ways. No source voltage or poor connection to source voltage.

At the moment the alternator is out of the picture, though it could very easily be the cause of a bad battery. First step..... check the battery.

__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

Gotcha. My followup question was one of ignorance. After re-reading my post, I remembered that approximately 10 months ago, while on a trip, the car stopped and a replaced regulator took care of the problem. While we bought a new battery at that time, we also ran the battery down a few times before the problem was solved.

Hans