Sierra 55 Amp Alternator 18-5966-1 for MerCruiser GM V-8 Engines
Sierra 55 Amp Alternator 18-5966-1 for MerCruiser GM V-8 Engines
The Sierra 18-5966-1 is a 55 amp alternator built for MerCruiser GM V-8 sterndrive applications. It supplies reliable charging output to keep the starting battery and onboard electronics topped off during engine operation, replacing a worn or failed factory unit with a direct-fit part sized for the same engine bay.
The housing has a machined exterior finish for a clean, factory-correct appearance. At 8.25 x 6.13 x 6.13 inches and 11.34 pounds, it mounts using the factory bracket and pulley arrangement on the applicable MerCruiser GM V-8 engines listed below.
This alternator is cataloged against a range of MerCruiser GM V-8 engine and drive combinations, including 440 TRS, 454 Mag., 460 TRS, 465, 500 Bulldog, and 502 Mag. Bravo engines across their respective model years. Confirm your engine model and year against the fitment list before ordering.
Specifications
- Brand: Sierra
- Manufacturer Part Number: 18-5966-1
- Product Type: Alternator
- Amperage: 55 Amp
- Exterior Finish: Machined
- Product Dimensions: 8.25 x 6.13 x 6.13 inches
- Weight: 11.34 pounds
- UPC: 808282387068
Fitment
- MerCruiser 440 TRS GM V-8, 1983-1986
- MerCruiser 454 Mag. GM V-8, 1986-1994
- MerCruiser 454 Mag. GM V-8, 1995-1997
- MerCruiser 460 TRS GM V-8, 1983-1986
- MerCruiser 465 GM V-8, 1990-1994
- MerCruiser 500 Bulldog GM V-8, 1990-1996
- MerCruiser 502 Mag. Bravo GM V-8, 1990-1993
Replaces (OEM)
- No OEM cross-reference numbers are listed for this part.
Frequently Asked Questions
What amperage does the Sierra 18-5966-1 alternator produce? This alternator is rated at 55 amps, sized to keep the starting battery and onboard electronics charged on applicable MerCruiser GM V-8 engines.
Which MerCruiser engines does the 18-5966-1 alternator fit? The 18-5966-1 is cataloged for MerCruiser GM V-8 440 TRS (1983-1986), 454 Mag. (1986-1994 and 1995-1997), 460 TRS (1983-1986), 465 (1990-1994), 500 Bulldog (1990-1996), and 502 Mag. Bravo (1990-1993) engines.
What are the dimensions of this alternator? The Sierra 18-5966-1 measures 8.25 x 6.13 x 6.13 inches.
How much does the 18-5966-1 alternator weigh? It weighs 11.34 pounds.
What finish does the alternator housing have? The housing on the 18-5966-1 has a machined exterior finish.
Does the 18-5966-1 fit both 454 Mag. Model years? Yes, part number 18-5966-1 is listed for MerCruiser 454 Mag. GM V-8 engines across both the 1986-1994 and 1995-1997 model spans.
Is this a genuine Sierra part or aftermarket? The 18-5966-1 is a Sierra-branded alternator, sold under Sierra's own part number rather than an OEM engine manufacturer number.
Will the 18-5966-1 work on a 500 Bulldog engine? Yes, it is cataloged for the MerCruiser 500 Bulldog GM V-8 engine for the 1990-1996 model years.
What is included when I order this alternator? The order includes one Sierra 18-5966-1 55 amp alternator unit.
Does this alternator fit the 502 Mag. Bravo? Yes, the 18-5966-1 is listed for the MerCruiser 502 Mag. Bravo GM V-8 engine for the 1990-1993 model years.
What is the manufacturer part number for this alternator? The manufacturer part number is 18-5966-1, made by Sierra.