80 280CE (12.3 v from alternator)

[Fulcrum525]

Friend called me last night saying the car wouldn't start. Got there and noted a dead battery so I jump started it and we got the car to my house. Checked the voltage regulator and it still has plenty of meat on the bushings. Went to Sears for a charging system test. I was told that the alternator was only putting out 12.3 volts. (Was told it needs to be at least 13.5 volts)

Time for a replacement alternator? (They made a few calls and found that a local auto zone has two in stock.) Also the battery is an autozone battery and still under warranty (The only good news i've gotten in a while)

[kiwi_bloke_nz]

If you measure voltage across the battery poles while the engine isn't running a fully charged / good battery should put out over 13 volts.

When the engine is started, if it is charging the voltage should rise and maintain at least 13.5 volts.

So yes, if it is only putting out 12.3 volts something is wrong. Even if the bushes on the voltage regulator are good, it could still be faulty.

[Fulcrum525]

Originally Posted by kiwi_bloke_nz

If you measure voltage across the battery poles while the engine isn't running a fully charged / good battery should put out over 13 volts.

When the engine is started, if it is charging the voltage should rise and maintain at least 13.5 volts.

So yes, if it is only putting out 12.3 volts something is wrong. Even if the bushes on the voltage regulator are good, it could still be faulty.

Yeah that sounds about right.

He tested from the battery terminals after I started the car (Or rather, jump started) I normally wouldn't trust autozone with this car but even they shouldn't be able to screw up while replacing an alternator. I would do it myself but time is a factor (Unless my friend is willing to hold off till Saturday when I planned to replace the rear glass anyways)

Amazing that a difference of 1.2 volts would have such an effect (I really need to learn more about electricity )

EDIT: And then suddenly I asked myself "Wait a second....does autozone even do repairs?" Looks like i'll be doing the swap on Saturday. Hopefully it goes more straightforward then that starter replacement went....)

[Fulcrum525]

Alright the new alternator install went straight forward. Probably one of the easier things that i've ever replaced on a Mercedes. The key in the old alternator sure put up a fight while trying to remove it and even then it didn't make things easy trying to get into the new one. (Thankyou grinding wheel )

The swap went so smoothly that I had time to tackle the rear passenger side glass installation as well. Now that presentsted and interesting challenge as the rear slide rail was not mounted to the cars body . (The hole for the screw became too big and it couldn't be mounted. (If I could get access to hole from underneath I would have just bolted it in place but that wasn't possible.)

So what I did was take a small 90 degree piece of steel that had a hole in it and I drilled through the sheet steel and simply bolted that in place on top of the bottom of the slide rail. I secured it tight enough to hold the rail in place. Not exactly factory but hey, it worked Getting the glass in place was the hardest thing to do (I can only imagine how hard it would be to do that job on a car that has pillars)