Bosch Alternator 12V 120A 1986A00856

The Bosch Alternator 12V 120A, part number 1986A00856, is a new alternator for 12-volt charging systems with a 120A charge current. It uses an internal regulator and is listed as an alternator type excl. vacuum pump, so the physical layout needs to suit that application before purchase.

Key mounting details matter on this unit: mount leg thickness is 56mm, mount centre to centre is 156mm, pivot hole diameter is 10mm and adjusting hole diameter is 10mm. The alternator mount is a single leg with a single pivoted lever fastening type, which makes correct alignment and bracket match essential.

The pulley is a 6 groove design with a 50mm outside diameter. Recommended related repair work includes a V-belt or V-ribbed belt if the existing drive belt shows wear, as belt condition can directly affect charging performance and belt tracking.

Key Features

• Bosch alternator, part number 1986A00856
• 12V unit with 120A charge current
• New alternator, not remanufactured
• Internal regulator fitted
• Excludes vacuum pump type
• 6 groove pulley, 50mm outside diameter

Specifications

• Brand: Bosch
• Product type: Alternator
• Part No.: 1986A00856
• Voltage: 12V
• Charge current: 120A
• Power rating: 120A
• Regulator type: Internal
• Alternator type: Excl. vacuum pump

Confirmed fitment notes

• Listed fitment includes Mercedes-Benz applications.
• Fitment references include Mercedes-Benz C-Class, Mercedes-Benz CLK, Mercedes-Benz M-Class and Mercedes-Benz SLK.
• Sample applications shown include Mercedes-Benz C-Class 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007 and 2008.
• Fitment data is grouped by Mercedes-Benz and model families rather than a full engine-by-engine or chassis-by-chassis breakdown.

Application and Buying Notes

Before ordering, compare the part number 1986A00856 and the physical mounting details against the unit already fitted to the vehicle. The important checkpoints on this Bosch alternator are the 12V electrical system, 120A output, 56mm mount leg thickness, 156mm mount centre to centre, 10mm pivot hole and 10mm adjusting hole.

The alternator uses an internal regulator and a 6 groove pulley with a 50mm outside diameter. Those details need to match the vehicle’s charging system and belt drive arrangement, especially on applications where the alternator is listed as excl. vacuum pump.

If the existing alternator is noisy, charging inconsistently, or the belt system is worn, it is sensible to inspect the drive belt and related hardware at the same time. The recommended additional repair is a V-belt or V-ribbed belt, which is often checked whenever an alternator is replaced.

This unit is listed as new and carries a 12 months warranty. Even so, alternator replacement should still be confirmed against the actual installation on the vehicle, because mounting style, pulley specification and regulator setup must line up with the existing system for a correct fit.

Before supply, the safest approach is to confirm the original unit details against the listed part number, voltage, output rating, mounting arrangement, and pulley configuration. That checking process is standard practice in the parts trade because visually similar units can still differ in service-critical ways.

For workshop, fleet, and equipment applications, accurate identification of part number 1986A00856 helps avoid unnecessary freight, additional labour, and vehicle or machine downtime. Where the application is not straightforward, the original unit, OEM reference, or workshop records should be used as the primary confirmation point.

Relevant published details for this unit include Type ALTERNATOR, Unit of Measure EACH, Warranty 12 Months, Mount Leg Thickness 56mm, Pivot Hole Diameter 10, Pulley Outside Diameter 50mm, Regulator Type Internal, Voltage 12, Mount Cnt to Cnt 156mm, Alternator Charge Current [A] 120.

Additional published details for cross-checking include Alternator Type excl. vacuum pump, Packaging length 23.9, Packaging height 20, Product Group 2 ALTERNATORS, Part No. 1986A00856, Brand BOSCH, Description Bosch Alternator 12V 120A, Adjusting Hole Diameter 10, Pin Code IR139.

Bosch Alternator 12V 120A. Part number 1986A00856 should be checked first. Listed voltage is 12. Listed output rating is 120. These details form the core reference points used by parts interpreters when confirming the correct replacement.

Mount style is Single Leg. Regulator type is Internal. Pulley configuration is 6 Groove. Those physical and electrical details should line up with the original unit before the replacement is approved for fitment.

For part number 1986A00856, the normal identification sequence is part number, electrical rating, mounting arrangement, connector or terminal style, and pulley or drive details. Using those checkpoints helps confirm that the listed unit matches the service requirement rather than only looking similar.

For a alternator in workshop, fleet, trade, agricultural, or construction service, the listed voltage 12 and output 120 should be checked carefully. Incorrect selection can affect installation time, return freight, and equipment availability.

Compatibility note: Confirm compatibility using part number 1986A00856, the 12V 120A specification, the internal regulator, the single leg mount, and the 6 groove pulley details before purchase. Fitment is listed for selected Mercedes-Benz applications, but the vehicle should still be checked against the exact mounting and drive setup.

FAQ

What is the part number for this Bosch alternator?

The part number is 1986A00856. For this listing, part number 1986A00856 is the main reference point. Listed voltage is 12. Listed output rating is 120. Published fitment references include MERCEDES-BENZ C-CLASS, MERCEDES-BENZ C-CLASS 2000, MERCEDES-BENZ C-CLASS 2001. These details should still be checked against the original unit before ordering.

Is this alternator 12V or 24V?

It is a 12V alternator. For this listing, part number 1986A00856 is the main reference point. Listed voltage is 12. Listed output rating is 120. Published fitment references include MERCEDES-BENZ C-CLASS, MERCEDES-BENZ C-CLASS 2000, MERCEDES-BENZ C-CLASS 2001. These details should still be checked against the original unit before ordering.

What is the output rating?

The alternator is rated at 120A charge current, and the power rating is also listed as 120A. For this listing, part number 1986A00856 is the main reference point. Listed voltage is 12. Listed output rating is 120. Published fitment references include MERCEDES-BENZ C-CLASS, MERCEDES-BENZ C-CLASS 2000, MERCEDES-BENZ C-CLASS 2001. These details should still be checked against the original unit before ordering.

Does it have an internal regulator?

Yes. The regulator type is listed as internal. For this listing, part number 1986A00856 is the main reference point. Listed voltage is 12. Listed output rating is 120. Published fitment references include MERCEDES-BENZ C-CLASS, MERCEDES-BENZ C-CLASS 2000, MERCEDES-BENZ C-CLASS 2001. These details should still be checked against the original unit before ordering.

What pulley does it use?

It has a 6 groove pulley with a 50mm outside diameter. For this listing, part number 1986A00856 is the main reference point. Listed voltage is 12. Listed output rating is 120. Published fitment references include MERCEDES-BENZ C-CLASS, MERCEDES-BENZ C-CLASS 2000, MERCEDES-BENZ C-CLASS 2001. These details should still be checked against the original unit before ordering.

What vehicles are shown in the fitment data?

The fitment data lists Mercedes-Benz applications, including C-Class, CLK, M-Class and SLK references, with sample C-Class years shown from 2000 through 2008. For this listing, part number 1986A00856 is the main reference point. Listed voltage is 12. Listed output rating is 120. Published fitment references include MERCEDES-BENZ C-CLASS, MERCEDES-BENZ C-CLASS 2000, MERCEDES-BENZ C-CLASS 2001. These details should still be checked against the original unit before ordering.