Alternator Volatage Regulator dissapointments

[Stevester 500E]

One of the local MB Master Mechanics in town once told me that Mercedes was ahead of there time by have modules for the different systems of a car.

But man, I sure think that MB was behind the curve when it comes to batter not charging warnings.

My alternator voltage regulator went out on me without any warning signs.
When the brushes got really worn, there were no signs that my regulator was keeping the alternator from charging my battery.

Thanks to a forum thread on another MB forum, I quickly found out what the problem was.

This is what I like about forums. Thanks to all who share their knowledge out in the automotive community.

 

[nocfn]

BTDT. I have a replacement for the C126 and the E500 in the trunk's goodie bag.

 

[RicardoD]

I have a old service receipt for this where the car was towed to the dealer for this. Seems a like a common problem and something that should be pro-actively taken care of on higher mileage cars.

 

[emerydc8]

In August 2021, I replaced my voltage regulator with a Bosch VR, made in Taiwan. Tonight, I noticed that at idle, when in drive, the instrument cluster and headlights flicker very slightly. When I put the car in neutral and the idle increases slightly, the flickering stops. I suspect this is a voltage regulator problem, but I'm surprised this Bosch VR would give me trouble so soon. I can live with it, but if this is a sign of a failing VR, I'd rather deal with it now. Maybe Bosch should have kept production of this in India. I got this from AutoHausAZ. Has anyone recently purchased a VR that was made in India?

 

[gsxr]

Jon, what is the voltage measured at the battery with a meter, when the lights flicker?

Even the OE MB VR's are now made in Taiwan, but the dealer charges ~6x for the same thing in a different box.

 

[gerryvz]

Unfortunately I think this is one part where the quality has slipped from what it once was -- the manufacturing has gone from Germany, to the UK, to India, and in recent years to Taiwan. And I think with each move, quality has slipped. I'd just consider this a "consumable" part and stockpile a couple of spares, as I have. I think I have one UK spare and one from India.

It's the nature of the beast nowadays.

All that said, some diagnosis of the problem is probably warranted, as a failure in less than a year of a VR does seem somewhat suspicious.

 

[JC220]

Just to note also here that I am lucky to have a great specialist rebuilder near my home. Indeed probably the best in the country!

There are several other components in an alternator which can fail. Diodes / rectifier etc.

I would rarely just swap a VR and expect good results.

I do always pull the alternator, in many cases proactively since they are now decades old and let him strip and rebuild them.

New slip ring, bearings, VR and bench testing of complete unit. (Including diode and rectifier tests the whole lot) etches his ref no for warranty on the case and provides a print-out of the performance etc when tested. All for about £50 in most cases.

So just note it's probably better use a specialist where you can to test and repair the whole unit.

Repairing original units is always preferable in my book to say buying unknown China etc new ebay ones.

Beware of rebuilt alternators on ebay etc you could be buying a ball of sh+te. Best get the high quality original alternator rebuilt by an experienced professional and you will have no issues.

 

[speedy300dturbo]

CrockAuto shows a Hitachi/Huco VR (made in Germany) available for the 1993 500SL, but this part doesn’t show up when selecting a 1992-1994 E500E.

 

[emerydc8]

I'll check the voltage when it flickers and report back. I never thought I'd be looking for a Bosch part made in India rather than Taiwan. This is my daily driver and I don't want the inconvenience of being down for weeks while someone rebuilds the alternator or VR, not that I know anyone in town that I would even trust to do it. I think GVZ is right--the quality on these VRs has gone down the tubes and it's now hit-or-miss to find one that will last.

 

[emerydc8]

FOLLOW UP:

The flickering lights (interior and exterior) started to occur at higher RPMs too, so I changed out the voltage regulator a few days ago with another Made in Taiwan voltage regulator. I ordered two more from AutohausAZ to have as spares, in case the shoddy quality is now standard for all Bosch regulators. As of now, they are still shipping the Taiwanese regulators--probably the only choice for them other than URO. At $11, I suppose you get what you pay for; although considering the time it takes to remove and replace the alternator, I would gladly pay $50 for a quality (German/Indian?) unit that's not going to strand me somewhere. I think these will go in the trunks of my cars.

 

[Jlaa]

FOLLOW UP:

The flickering lights (interior and exterior) started to occur at higher RPMs too, so I changed out the voltage regulator a few days ago with another Made in Taiwan voltage regulator. I ordered two more from AutohausAZ to have as spares, in case the shoddy quality is now standard for all Bosch regulators. As of now, they are still shipping the Taiwanese regulators--probably the only choice for them other than URO. At $11, I suppose you get what you pay for; although considering the time it takes to remove and replace the alternator, I would gladly pay $50 for a quality (German/Indian?) unit that's not going to strand me somewhere. I think these will go in the trunks of my cars.

@emerydc8 --- it looks like the Indian Bosch unit can be found on Amazon:

Amazon.com: Bosch 1197311242 Voltage Regulator : Automotive

Buy Bosch 1197311242 Voltage Regulator: Voltage Regulators - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

www.amazon.com

 

[emerydc8]

Thanks. I wish I had known two days ago.

 

[gsxr]

@emerydc8 --- it looks like the Indian Bosch unit can be found on Amazon:

https://www.amazon.com/Bosch-Automotive-1197311242-Voltage-Regulator/dp/B001CO17TQ/

Warning - just like with FCP/AHAZ/RME/etc, photos of products on Amazon are NOT necessarily what you receive. They are often stock photos, or pictures of what the old item had been when first listed for sale. In this case it might have been circa 2008. Now, with only 1 left, there's a chance this could really be old-stock Indian VR's... anyone want to roll some dice? Be careful out there!!

 

[emerydc8]

I wouldn't pay six times more for possibly the same regulator. Good research, Dave.