Is This The Correct Voltage Regulator For My Alternator? - PeachParts Mercedes-Benz Forum

Squiggle Dog · #1 01-30-2013, 05:10 PM

I have a new voltage regulator in the box, and removed my old one. Looking at the part numbers, the old one is 1 197 311 009, while the new one is 1 197 311 028.

They look identical (both are EL 14V 4C), but the old one has a resistor or something up top that the new one lacks. Also, the brushes on the new one are much longer than the old one, but that is probably due to wear.

I want to make sure this new regulator is compatible with my car so I don't mess up anything. I'm not sure what type of alternator I have, but I think maybe it is the 55AMP type, as I think this was standard on the W116 300SD.

Thanks for the help.

97 SL320 · #2 01-30-2013, 07:05 PM

On the old reg / brush holder, the brush nearest the black regulator cap is worn beyond contact and would cause a no charge condition.

There is a resistor on the old one that runs across the regulator portion. Near as I can tell this was done to provide some charging even if the regulator failed. The resistor value would key off of electrical requirements that never go away if the car is running. ( Electric fuel pump , engine computer , injectors , ignition system , transmission control. )

Not all cars use this resistor, my 97 SL 320 has one but the same regulator used on a Audi or SAAB does not.

Jeremy5848 · #3 01-30-2013, 08:04 PM

Those are Bosch part numbers; they don't necessarily translate into Mercedes numbers. My 1987 300D Turbo used the identical Bosch part in its (65W?) alternator so I think you're safe. AFAIK these regulators are pretty much all the same.

If no one can provide exact part numbers, and confirm you have the right part (or not) here's something you can try: Install the new regulator in your alternator (this assumes it's physically the right size). Then re-connect the battery, put a voltmeter connected to the battery where you can see it and start the engine. The voltage should drop down to 9 or 10 volts under the load of the glowplugs and then come up to no more than 15 volts when the engine starts, preferably 14.something. The alternator light should go out. If the voltage goes significantly over 15 volts then there is a problem; immediately shut down and seek another regulator. If the voltage is under 13 volts there is also a problem. If the alternator light doesn't go out there is a problem.

Jeremy

Squiggle Dog · #4 01-30-2013, 09:08 PM

Thanks for the replies. I had a dead battery a couple weeks ago. Maybe it wasn't so much a bad battery as the alternator wasn't charging it.

I looked at the alternator on the spare engine I have (from a 1979 W116 300SD), which has a shiny label that reads "BOSCH, 55A" and it has a large rectangular voltage regulator and what I think is a condenser.

I'm not sure what type of alternator I have on my 1980 W116 300SD as there is no label currently on it (there is also no condenser). I looked on Pelican Parts, and for a 1980 300SD it shows a picture of one with what appears to be part number 1 197 311 090. It calls this a "short brush" regulator. The old one is marked 1 197 311 009. Maybe this is the replacement?

I looked up the new one I have and Pelican Parts shows it as a "long brush" regulator. Maybe the only difference between the regulators is the brush length, and if I install the long brush type, I wonder if it would damage anything if it fits.

I can certainly install it and test the voltage.

Squiggle Dog · #5 01-30-2013, 09:51 PM

I got some big help from JasonP on W116.org. He showed me this .pdf listing the Bosch voltage regulators: http://www.regitar.com/FlyerPDF/cs.pdf

The original voltage regulator removed from my car (1 197 311 009--page 15) is intended for a 28mm OD slip ring. The brushes are D+/L and F. The ground is on the left side and it has a resistor. 14.7V

The new voltage regulator in the box (1 197 311 028--page 18) is also intended for a 28mm OD slip ring, brushes are also D+/L and F, and the ground is also on the left side. It seems identical except for lacking the resistor (possibly for partially charging if the regulator totally fails). 14.7V

The voltage regulator listed on Pelican Parts (1 197 311 090--page 20) is intended for a 32mm OD slip ring, which means the brushes are shorter than my original part. The brushes are A and F, which is a different configuration than my original part. The ground is on the right side, which is different than my part. No resistor. 14.7V

What I can deduce from this is that the original voltage regulator is the long brush type. The only difference between the original part and the new one is the lack of a resistor in the new one. I am not sure if this will matter, or be worth trading for another one since it seems it will do the job.

The reason the voltage regulator listed on Pelican Parts isn't the one for my application could be because I either have a late production W116 or a newer alternator. The alternator on my spare 1979 W116 300SD engine uses a square voltage regulator, no doubt the short brush type.

Squiggle Dog · #6 01-30-2013, 10:34 PM

When I look up the W116 450SEL on Pelican Parts, it shows both long and short brush voltage regulators available, so the same information can probably be used toward the W116 300SD.

Why does it seem only 1 197 311 090 (short brush) 1 197 311 028 (long brush) are available, and not the original 1 197 311 009 long brush with resistor? Perhaps the resistor model 1 197 311 009 was phased out by Bosch since 1 197 311 028 is identical and the resistor is not a necessary function.

dude99 · #7 01-30-2013, 10:39 PM

Not sure if it will help at all but I know that the long brush regulator was used with the w126 300sd.

http://www.peachparts.com/shopforum/diesel-discussion/333508-long-brush-regulators.html

Squiggle Dog · #8 01-30-2013, 10:42 PM

The old-style rectangular voltage regulators like my 1979 part engine has (0 192 052 004--page 14) is also intended for a 32mm OD slip ring and has the A and F brushes.

So, the old style is 32mm slip ring, A and F short brushes. The newer style is 28mm slip ring, D+/L and F long brushes--resistor optional. Just for fun, I might pull off the voltage regulator on my 1979 parts engine and take a look at the slip ring to see if I can notice a difference in size between it and the alternator in my 1980.

I did notice that my slip ring has deep grooves in it, so I may be into replacing it sometime soon.