1986 Porsche 944 Bosch Alternator Part Number: Complete Guide

If you own a 1986 Porsche 944, you may be searching for the correct Bosch alternator part number. This guide covers exactly that. Whether you have the base 944 or the 944 Turbo (951), choosing the right alternator is essential for reliable charging. We'll break down the factory part numbers, what they fit, and what to look for when buying a replacement.

Understanding the 1986 Porsche 944 Alternator

The 1986 Porsche 944 came with alternators from Bosch. The standard output was 90 amps for the naturally aspirated 2.5L engine, while the 944 Turbo often used a 115-amp unit. The part numbers differ between these models, so it's critical to identify your engine and any modifications.

Stock Bosch Alternator Part Number for 1986 944 (Naturally Aspirated)

For the standard 1986 Porsche 944 (non-turbo), the original factory Bosch alternator part number is 0120 525 031. This is a 90-amp alternator. It is also sometimes listed under 0 120 525 031 (with spaces). The OEM Porsche part number for this alternator is 944.603.108.01 or 944 603 108 01. Note that Porsche part numbers may have been superseded; check with your dealer or supplier for the latest revision.

This alternator fits the 2.5L inline-4 (M44/40 engine) used from 1985.5 to 1988 (early offset engine). The 1986 model year is part of that generation.

Bosch Alternator Part Number for 1986 944 Turbo

The 1986 Porsche 944 Turbo (951) uses a higher-output alternator. The Bosch part number is 0 120 525 036 (or 0120 525 036). This is a 115-amp unit. The corresponding Porsche number is 944.603.109.01 (or 944 603 109 01).

It is important not to mix these up. A 90-amp alternator will work if your electrical load is low, but the Turbo has higher demands (more electronics, fuel injection, etc.). Using a lower-output alternator could lead to low battery voltage, especially at idle.

Differences Between the Two

The 90-amp and 115-amp alternators have the same physical dimensions and mounting points, but the internal regulator and stator are different. The 115-amp unit has a different pulley design in some cases, and the wiring plug may be identical. Always confirm that the connector matches your car's harness. For 1986 models, the alternator uses a two-pin round connector (B+ terminal and a field wire).

Aftermarket Alternatives and Interchanges

If you cannot find a genuine Bosch unit, several reputable brands offer replacements. Be aware that remanufactured alternators are common and can be a good value. When ordering, provide your car's VIN or confirm the engine code to ensure correct fitment.

Bosch Remanufactured Alternators

Bosch itself offers remanufactured units under the "Bosch Reman" line. For the 944 NA, the part number is often the same (0120 525 031) or may have an "R" suffix. For the Turbo, the reman number may be 0120 525 036R. These are rebuilt to factory specs and typically include a new regulator and bearings.

Other Brands

• Valeo: Some 944s originally used Valeo alternators, but the Bosch is more common. If you have a Valeo, the part number will be different. Check your current alternator.
• Delco Remy: Offers a compatible alternator under the part number 19020151 for the 944 NA (90-amp). For the Turbo, look up 19020152 (115-amp). Cross-reference with your vehicle.
• Denso: Not a common fit but some aftermarket units may use Denso internals.

How to Identify the Correct Alternator for Your 1986 944

Before buying, inspect your existing alternator. Look for a white sticker or engraved number on the case. Often the Bosch number is stamped into the metal housing near the regulator. Also check the Porsche part number on a label if still present.

Another method: use the production date. 1986 model year 944s built from August 1985 to July 1986 use the 90-amp unit. If your car is equipped with options like air conditioning, fog lights, or rear window defroster, the 90-amp is still adequate, but the Turbo's requirements are higher. If you have a non-turbo and plan to add electrical accessories (stereo, lights), you might consider upgrading to a 115-amp, but that requires swapping the alternator and possibly the wiring. It's not a simple plug-and-play; you may need to upgrade the alternator cable and fuse.

Replacement Tips for the 1986 Porsche 944 Alternator

Replacing the alternator on a 1986 944 is moderately straightforward if you have basic mechanical skills. Here are key points:

• Disconnect the battery before starting any work.
• Remove the drive belt (serpentine or V-belt depending on your engine). You'll need a 13mm socket for the adjustment bolt.
• Unbolt the alternator: two bolts (one long, one short) securing it to the bracket.
• Carefully disconnect the wiring: the B+ terminal (large red wire) and the two-pin connector.
• Install the new alternator in reverse order. Torque the bolts to 25 Nm (18 ft-lb) for the pivot bolt and 20 Nm (15 ft-lb) for the adjuster bolt.
• Check belt tension: approximately 10mm deflection at the longest span.

Common Pitfalls

• Wrong part number: Double-check that the alternator matches your engine and model year. The 1986 944 uses a different alternator than later years (after 1987, the engine moved to a different mounting).
• Incorrect pulley: Your old alternator's pulley may be swapped onto the new one if the belt type differs. Turbo and non-turbo pulleys are often the same, but verify the number of grooves.
• Regulator issues: Some aftermarket alternators may have a different regulator that affects charging voltage. Stick with Bosch or a known brand to maintain proper 13.5-14.5 volts.

Final Recommendation

For a 1986 Porsche 944 (non-turbo), the recommended Bosch alternator part number is 0120 525 031 (90 amps). For the 1986 944 Turbo, use 0120 525 036 (115 amps). If you are buying a remanufactured unit, look for the same base number with an R suffix. Avoid generic parts that don't list specific fitment; they may cause charging issues.

Before purchasing, verify the date code on your vehicle: an early 1986 car (built before September 1985) might have a different alternator? Actually, the 1986 model year started in August 1985, so all 1986 944s should use these numbers. However, if your car has been modified or has a different engine, cross-reference with the VIN to be safe.

If you need the best reliability, a new Bosch alternator is the safest choice. Remanufactured can be acceptable but check for a warranty. Always inspect the condition of the voltage regulator and brush pack if you're rebuilding an old unit.

Ultimately, knowing the exact Bosch part number for your 1986 Porsche 944 alternator will save you time and money. Use the information above to make an informed purchase and get your car charging properly again.