V12 PROPELLERS
IMPORTANT: This document guides our dealers, boatbuilders, and company service personnel in the proper installation or
service of our products. If you have not been trained in the recommended servicing or installation procedures for these or
similar Mercury Marine products, have the work performed by an authorized Mercury Marine dealer technician. Improper
installation or servicing of the Mercury product could result in damage to the product or personal injury to those installing or
operating the product. Always refer to the appropriate Mercury Marine service manual for component removal and installation
instructions.
NOTE: After completing installation, place these instructions with the product for the owner's future use.
Components Contained in Kit
b
a
71703
Front Propeller Kit Description
Ref. Qty. Description
a 1 Front propeller (4‑blade)
Rear Propeller Kit
Ref. Qty.
b 1 Rear propeller (3‑blade)
Propeller Installation
! WARNING
Accidental engine starting can cause serious injury or death. Remove the key from the ignition switch and engage the
lanyard stop or E‑stop switch to prevent the engine from starting when performing service or maintenance on the power
package.
IMPORTANT: Mercury Marine V12 propellers are matched sets. Do not operate the engine without a front and rear propeller
of the same pitch.
1. Apply a liberal amount of Extreme Grease to all splined, threaded, and tapered surfaces on the propeller shaft, thrust
hubs, propeller nuts, and propeller hubs.
Tube Ref No. Description Where Used Part No.
Extreme Grease Inner and outer propeller shaft splines, large thrust hub, 8M0071842
small thrust hub, large propeller nut, small propeller nut,
front propeller hub, rear propeller hub
2. Slide the large thrust hub onto the outer propeller shaft with the tapered end of the hub facing rearward.
3. Align the splines of the front (4‑blade) propeller with the splines on the shaft and slide the propeller into place on the
outer shaft.
4. Insert a block of wood between the propeller blades and the anti‑ventilation plate, to prevent the propeller from turning
during tightening of the propeller nut.
5. Install the large propeller nut and tighten the nut to the specified torque using a propeller nut tool.
90-8M0166975 eng APRIL 2021 © 2021 Mercury Marine Page 1 / 2
V12 PROPELLERS 8M0171389
Propeller Nut Tool
Aids in the removal and installation of the large propeller nut.
71752
Description Nm lb‑in. lb‑ft
Large propeller nut 339 – 250
6. Slide the small thrust hub onto the inner propeller shaft with the tapered end of the hub facing rearward.
7. Align the splines of the rear (3‑blade) propeller with the splines on the shaft and slide the propeller into place on the inner
shaft.
b c a - Large thrust hub
a de b - Front (4‑blade) propeller
c - Large propeller nut
d - Small thrust hub
e - Rear (3‑blade) propeller
f f - Small propeller nut
71705
8. Insert a block of wood between the propeller blades and the anti‑ventilation plate, to prevent the propeller from turning
during tightening of the propeller nut.
9. Secure the propeller with the small propeller nut. Use a 1‑13/16 in. socket to tighten the nut to the specified torque.
Description Nm lb‑in. lb‑ft
Small propeller nut 135.6 – 100
72406
Propeller installation with a block of wood between blades and anti-ventilation plate (typical)
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© 2021 Mercury Marine 90-8M0166975 eng APRIL 2021