Mercruiser outdrive parts | Alpha one lower unit repairs

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Mercruiser Alpha One lower unit parts drawing

Lower gearcase housing exploded view component drawing 1 - 25

  • Mercruiser and Alpha One (up to 1990) exploded view lower unit drawing
  • Water pump components, impellers, seals and shafts
  • Manufactured by GLM, California. All parts include a 2 year warranty
  • Easy to identify photos with OEM Mercury numbers

Mercruiser parts breakdown 1-25

Photo
Description / OEM #
Price
(USD)
Price (Canadian)
12120 Water pump impeller kit V4-V6-V8

12120 Water pump

Item A
P/N 12120
Complete water pump kit (1984 - 1990, MR and Alpha One, serial numbers 6854393-OD469858). Click on picture for older MC-1, R and 1991 and up Gen 2 models.

$35.95

$46.95

51220 GM manifold V6 exhaust assembly

51220 GM manifold

Item B
P/N 51220
GM 4.3L V6 exhaust manifold, center rise for 1986 and up models. Click on photo for all other engine / model manifolds.

99746A17

$218.95

$288.95

18100 Lower Unit 1623-8951A43

18100 Lower Unit

Item C
P/N 18100
New lower unit assembly for all ratios and motors, up to 330 hp. 2 year warranty (1970 - 1990, MC-1, R/MR and Alpha One, serial numbers 2791957 - 0A545003)

#1623-8951A43

$1399.95

$1846.95

12410 Pump housing

12410 Housing

Item 1
P/N 12410
Upper water pump housing (1966 - 1990)

#46-96148T1

$29.00

$36.00

 
Item 2
P/N 12810
Pump cup (included in upper housing and in P/N 12110 and 12120)

#48752

$5.00

$6.00

89840 Impeller

89840 Impeller

Item 3
P/N 89840
Impeller (1966 - 1990)

#47-89984T4

$15.00

$19.00

21720 Washer

21720

Item 4
P/N 21720
Washers (3 units)

12-36001

$4.00

$4.00

12821 Screw

12821

Item 5
P/N 12821
Screw

12-36001

$4.00

$4.00

21180 Lock nuts

21180

Item 6
P/N 21180
Lock nuts (5 units)

11-35888

$7.00

$8.00

12830 Seal

12830 Seal

Item 7
P/N 12830
Seal

26-38970

$4.00

$4.00

12820 Tube guide

12820 Tube guide

Item 8
P/N 12820
Tube guide

23-29804T

$4.00

$4.00

81160 O-rings

81160 O-ring

Item 9
P/N 81160
O-rings (5 units)

25-30613

$4.00

$4.00

21190 Nut

21190 Lock nuts

Item 10
P/N 21190
Nut (5 units)

11-826709111

$9.00

$11.00

21490 Washers

21490 Washers

Item 11
P/N 21490
Washer (5 units)

12-29245

$6.00

$7.00

11070 Key

11070 Key

Item 12
P/N 11070
Key

28-56654

$4.00

$4.00

31020 Gasket

31020 Gasket

Item 13
P/N 31020
Gasket

27-858524

$4.00

$4.00

12510 Wear plate

12510 Wear plate

Item 14
P/N 12510
Wear plate

32435-1

$4.00

$4.00

31010 Gasket

31010

Item 15
P/N 31010
Gasket

27-85608-1

$4.00

$4.00

12310 Pump base

12310 Base

Item 16
P/N 12310
Water pump base (1970 - 1983 only)

46-57234A1

$25.00

$31.00

85040O Oil seal

85040 Oil seal

Item 17
P/N 85040
Oil seal

26-16977

$8.00

$11.00

85070 OiI seal

85070

Item 18
P/N 85070
Oil seal

26-89238

$9.00

$12.00

82260 O-ring

82260

Item 19
P/N 82260
O-ring (5 units)

25-33145

$7.00

$9.00

31040 Base gasket

31040

Item 20
P/N 31040
Gasket

27-856704

$4.00

$4.00

21570 Roller bearing

21570 Roller bearing

Item 21A
P/N 21570
Bearing (1970 - 1983 only)

31-53079A1

$23.00

$28.00

21580-31-36387A1

21580

Item 21B
P/N 21580
Bearing (1984 - 1997 only)

31-36387A1

$32.00

$40.00

23300 Shims

23300 Shims

Item 22
P/N 23300
Shim

15-57007A1

$6.00

$7.00

21800 Washer

21800

Item 23
P/N 21800
Washers (5 units)

12-29395

$5.00

$6.00

30010 Washers

30010

Item 24
P/N 30010
Washers (5 units)

12-31266

$4.00

$4.00

85581 Seal

85581

Item 25
P/N 85581
Oil seal

26-816464-1

$7.00

$9.00