Recently while on vacation my 190E shutdown on the interstate.
The first sign of a problem was the turn signals quit working a short time later the engine quit. I was told that the alternator had gone bad and needed replacement. I would like to try removing the unit and have it repaired .

A battery charger was placed on the battery and the car restarted
and the battery seems to be holding a charge if discnnected from the car.

My quiestions are : How do I losen the belt and how do I remove the unit for testing.

Get a manual or do a search on here. If you have the original owners manual it should show you the belt routing. Make sure you draw it out prior to disassembly if you do not have the manual.
Once you get the belt out of the way there are two or three bolts that hold the altermator on. Remove those bolts, disconnect the wiring at the back of the alternator and it should then come out.

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Jim

We need to know what year the car is and what type of engine. There are a few different ones an d the procedure is different on each.

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1990 190E 2.6
1996 Grand Voyager 3.3
1985 Mustang GT 5.0 5 SPD
1982 Suzuki GS 750T

Some parts stores such as AutoZone will test your charging system in the car at no cost to you. This diagnosis often saves time and money.

I replace the voltage regulator / brush holder assembly first to see if it corrects the problem. On many vehicles it can be done by removing two screws with the alternator still on the car. The part cost is much less and the labor is about five minutes if access is easy. My best luck has been with Bosch regulators. Others may cost less but often have a shorter life or allow voltage surging.

If your alternator has over 100,000 miles on it, or is noisy, you may want to have the bearings / bushing replaced which requires removal of the assembly.

Good Luck,

JD

The regulators tend to fail before the alternator itself, or even the bearings. The regulators are typically very easy to replace, and so much cheaper that it may be worth just trying this first with no further debugging. On my 300E, I can do it without removing even the belt. Your 190E may differ.

Alas, my alternator did finally die. Probably could have replaced the brushes, bearings, etc., but time is money, so I bought a rebuilt unit for just $84.00 net (shipping and everything).

If you do decide for full replacement, I found that this vendor had better prices on rebuilt MB alternators than any salvage yard quote on a used unit, plus a 3 year warranty. 6 months later, I am still a very happy customer.

http://autoexpress.safeshopper.com

I pulled my alternator (did not need to loosen belt). Changed by brushes (brush pack) fix worked great.

Brush pack on my car can be changed easily without removing the alternator. As stated by others it's just two screws.

Easy job,
Good luck,
Joel

The brush pack is on the back of the alterntor.

My alternator finally died -- 12 years and 232,000 miles later. Amazingly, the bearings were still in seemingly perfect condition, but apparently a diode went bad (left side dummy lights wouldn't light -- only SRS, Check Engine, and ABS... regulator checked out fine)

I took csnow's advice and ordered from the vendor he linked above. Although, it's only been a day, so far so good. What was a pleasant surprise, though, was that it came with a new pulley attached. It wasn't expected, and I was dreading the thought of busting loose the old pulley.

Installation on the 103 is a snap. I removed the fan shroud, and instead of bothering with the belt tensioner, I manhandled the belt off the top pulley giving me enough slack to remove belt from alternator pulley.

Two long 15mm bolts hold it on, and it is very accessible from underneath, with the right side of car jacked up -- 1 hr to R&R, a very easy DIY job.

Car seems to be running quite a bit cooler, possibly due to more voltage spinning the aux fans -- but it's too early to tell for sure as I haven't had it in stop and go traffic yet.

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-Paul-
'01 E430, Sport 72,000 mi
'98 C280, 126,500 mi

Well that is a very impressive lifespan!

That $84 alternator still seems like the best deal going.
Volume and a very short distribution channel, I suppose.
The internet at its finest.

Mine is still going strong more than a year after I posted this link.
Hope it lasts 232k miles...

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1986 300E 5-Speed 240k mi.