MerCruiser R / MR
- Predecessor to the Alpha One
- Single propeller
- External trim cylinders
MerCruiser R / MR
- 1967–1990
Drive specs
| Model years | 1967–1990 |
|---|---|
| Type | Drives |
| Gear ratios | 1.98:1 · 1.84:1 · 1.65:1 · 1.5:1 · 1.32:1 |
|---|---|
| Oil type | Mercury/Quicksilver High Performance Gear Lube SAE 90 |
| Propeller system | Single propeller |
Capacity not listed in our sources; follow the workshop manual.
Lower unit variants
| Variant | Gear ratio | Year | Identification | Source |
|---|---|---|---|---|
| R/MR, 4-cyl 2.5 l | 1.98:1 | 1969–1983 | Tooth count 20/24 | PowerBoatSupply: gear ratio chart R/MR, Alpha One, Alpha One Gen II (external link) |
| R/MR, 6-cyl 165 | 1.65:1 | 1969–1983 | Tooth count 24/24 | PowerBoatSupply: gear ratio chart R/MR, Alpha One, Alpha One Gen II (external link) |
| R/MR, 470 (4-cyl) | 1.84:1 | 1969–1983 | Gear teeth 17/19 | PowerBoatSupply: gear ratio chart R/MR, Alpha One, Alpha One Gen II (external link) |
| R/MR, V8 260 | 1.5:1 | 1969–1983 | Gear teeth 20/22 | PowerBoatSupply: gear ratio chart R/MR, Alpha One, Alpha One Gen II (external link) |
| R (1983) | 1.32–1.98:1 | 1983 | Serial numbers 6225577–0D469828; lower unit 5356A4 | Sterndrives.com: drive table with serial numbers and gear ratios |
| MR (1984–1990) | 1.32–1.98:1 | 1984–1990 | Serial numbers 6225577–0D469828; lower unit 8951A37 (counter-rotating: 8951A39) | Sterndrives.com: drive table with serial numbers and gear ratios |
| Older drives 120/140, 160/165, 470/485, 888, 233 | 1.32–1.98:1 | 1967–1982 | Serial numbers from 2062141 up to 6225576 | Sterndrives.com: drive table with serial numbers and gear ratios |
Service points
- Drive oil: change it and check that it isn't milky (water)
- Bellows: U-joint bellows, exhaust bellows, shift cable bellows
- Gimbal bearing
- Sacrificial anodes
- Propeller and propeller shaft seals
Troubleshooting
Runs rough, stalls or loses power
Cooling and temperature
Electrics, alarms and fault codes
How to identify the drive
Decal on the port or starboard side of the upper drive shaft housing. On newer Bravo drives the number may be stamped behind the rear cover. The transom assembly has its own number on the inner or outer plate. Confirm the gear ratio from the markings or a serial-number-specific parts catalog.
Compare all drives →Official identification charts
- Sterndrives.com: MerCruiser Sterndrive Chart (years, serial numbers, gear ratios)
- Mariner's Warehouse: How to identify a MerCruiser outdrive (Alpha One, Gen II, Bravo)
- MercruiserParts: Where is my serial number
Spare parts
| Part | Part number | Note | Source |
|---|---|---|---|
| Bellows kit with exhaust bellows | 30-803097T1 | R, MR and Alpha One with exhaust bellows | Mercruiserparts.com: 30-803097T1 |
| Gimbal bearing | 30-879194A02 | MC-1, R and MR | PowerBoatSupply: gimbal bearing 30-879194A02 (MC-1, R, MR, Alpha 1974–1997, Bravo One 1988–1995) (external link) |
Exploded views & parts catalogs
- ShopMercruiserparts.com: exploded views (Mercury parts catalogue)
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Related models
Service guides
Sources
- PowerBoatSupply: gear ratio chart R/MR, Alpha One, Alpha One Gen II (external link)
- PowerBoatSupply: gimbal bearing 30-879194A02 (MC-1, R, MR, Alpha 1974–1997, Bravo One 1988–1995) (external link)
- Sterndrives.com: drive table with serial numbers and gear ratios
- Mercury Marine: MerCruiser – the leader in sterndrive innovation (blocks bots, opened in browser) (external link)
- Wikipedia: Mercury Marine (en) (external link)
- Mercruiserparts.com: 30-803097T1
- Mariner's Warehouse: identifying MerCruiser drives
- MercruiserParts: serial number location