Yes, probably. Much less expensive than an entire alternator, fortunately.

__________________

"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970

One would think so. But, that is a brush assembly as well as a voltage regulator and it looks like one brush is shorter than the other. There is no way to tell if the voltage regulator is bad - visually.

The assembly is bad, granted, by the way the brushes look. But I would be suspicious of the slip rings on the alternator. Do they have a bronze copper look? They should. Is where the shorter brush rides, blackened? It shouldn't be. It is typical that the brushes wear out, but so do the slip rings. How are the bearings? Are they noisy? With the belt off, do you hear a growling noise when you spin the alternator fan?

For a shot in the dark, I'd try replacing the regulator brush assembly. If that's not it, you'll have to replace the alternator but keep the new VR as a spare.

I don't typically replace just a VR because one can never know how long the alternator has been on the vehicle, unless of course you replaced it yourself or you have the service records. If the VR is bad, the alternator isn't far behind, IMHO.

Michael B.

__________________
1992 300CE - 157kMi (my white beauty)
1992 300CE - 220kMi (sold)
1990 300E - 189kMi (sold)
1990 300SL - 102kMi (salvaged parts available)
1986 300E - 230kMi (salvaged parts available)

Expert RV Generator Repair
Go To: MiGen Repair
When no one else can, I do!

We judge ourselves by our intent.
We judge others by their actions.

These alternators seldom fail, but the brushes and regulators do. Replace the regulator assembly.

__________________

Gone to the dark side

- Jeff

Toast... I smell toast. Does anyone else smell toast?

Inexpensive part. Just replace it and see shat comes.

BTW: I've been buying parts from Carquest lately since they are on the Worldpac supplier chain. Go online, get WP part # and take to Carquest. No worries about shipping.

Well, I replaced the VR with an OE Bosch replacement...but now the damn car won't start!

The glow plug light won't turn on, and the engine just cranks endlessly with no sign of starting. Also, the glow plug relay smells a bit like burnt electronics...I'm not sure what to do...

__________________
Current cars:
2000 ML55 AMG, 174k miles
2003 C240 T-Modell, 202k miles
1995 S320, 207k Miles

Check for power at the glow-plug relay with the key on. You might also try disconnecting the new regulator, then try starting, did you disconnect/change/mess with any of the wiring on the alternator?

Also we could go back to posts 3 and 11 with the possibility of a bad ignition switch.

__________________

Gone to the dark side

- Jeff

Well, i just tested the relay, and there is a full 12V at both ends of the fuse.

Still no glow plug light. I also checked the glow plugs, and they all seem fine, except for #3, which showed 15 Ohms.

__________________
Current cars:
2000 ML55 AMG, 174k miles
2003 C240 T-Modell, 202k miles
1995 S320, 207k Miles

Is the fuse hot with the relay off? I don't remember if the fuse is supply side or switched side of the relay.

Does the relay click when you turn the key on?

__________________

Gone to the dark side

- Jeff

Fuse has 12V with key off. So the fuse is on the supply side.

I do hear a relay click when I turn the key on, but I'm not sure if it's the glow relay...it could be something else.

__________________
Current cars:
2000 ML55 AMG, 174k miles
2003 C240 T-Modell, 202k miles
1995 S320, 207k Miles

Nobody? I guess I'll try taking the relay apart and cleaning the contacts.

__________________
Current cars:
2000 ML55 AMG, 174k miles
2003 C240 T-Modell, 202k miles
1995 S320, 207k Miles

The relay has 8 small wires to one plug IIRC, ground, six glow-plugs, and an ignition-switched hot. Check for 12v ign to ground to see if it is getting 12v with the key on, if so, check for 12v on any of the glow-plug wires.

__________________

Gone to the dark side

- Jeff

Hmm, good idea! It's the violet wire, correct? I'll check that as soon as my laundry is dry!

__________________
Current cars:
2000 ML55 AMG, 174k miles
2003 C240 T-Modell, 202k miles
1995 S320, 207k Miles

I'm more of a electricity and engine basics instructor, but I do know you need three things to make an engine run and they are; 1 - Compression, 2 - Ignition Source, 3 - Fuel Mixture.

One of the three are missing. Given the history of this thread, we can likely assume compression isn't the issue. With a diesel, the ignition source is the compression. So, that leaves fuel. At this point, I'll leave the responses up to others more qualified in the fuel controls.

Thought: What is your ambient temperature? If it's incredibly warm, then it should start (providing it's getting fuel delivery) with a little extra cranking. Below 80 degrees F, it may not light off without heat assistance (i.e. glow plugs). If you have a block heater, plug it in to bring the block temp up over 100 degrees and if you're getting fuel, it should start.

Again, I only know the basics, not the controls of the Diesels. Good Luck.

Michael B.

__________________
1992 300CE - 157kMi (my white beauty)
1992 300CE - 220kMi (sold)
1990 300E - 189kMi (sold)
1990 300SL - 102kMi (salvaged parts available)
1986 300E - 230kMi (salvaged parts available)

Expert RV Generator Repair
Go To: MiGen Repair
When no one else can, I do!

We judge ourselves by our intent.
We judge others by their actions.

Well, I tested for 12V Ign switched, and there is 12V at the relay with the ignition on, so it's not the ignition switch.

I then took apart the relay, and it smells very burnt...but I can't really see anything wrong with it...The relay contact points looked a bit dirty, so I sanded them a bit but it still isn't working. I manually pressed the contacts together, and was able to get the engine to start, sputter, then die. Ran for about two seconds.

Looks like I need a new glow plug relay... :[

__________________
Current cars:
2000 ML55 AMG, 174k miles
2003 C240 T-Modell, 202k miles
1995 S320, 207k Miles

I just ran 12V from the battery to each glow plug (that was fun) and it started instantly. I even have some good news! The alternator is now charging perfectly!

Bad news is that while I was walking up to it from behind, I noticed a few drip spots underneath the right rear wheel...looks like brake fluid is leaking from somewhere... WHAT NEXT???

__________________
Current cars:
2000 ML55 AMG, 174k miles
2003 C240 T-Modell, 202k miles
1995 S320, 207k Miles