Page 284 - REPOWER REFERENCE GUIDE (2020)

Critical Procedures

Tube Ref No. Description Where Used Part No.
25W-40 Synthetic Blend
139 4-Stroke Marine Engine Engine crankcase 92-8M0078629
Oil
2. Remove all spark plugs.
NOTE: Tag spark plug wires with temporary labels, as necessary to ensure that they are reconnected correctly.
3. Disconnect the coil wire from the distributor and connect it to a good ground.
IMPORTANT: Ensure that the ignition key is in the OFF position.
4. Connect the remote starter switch to the large, 12 volt terminal (typically a red battery cable) and the small terminal
(yellow/red cable) on the starter motor.
IMPORTANT: It is possible to perform this procedure using the boat's key switch instead of a remote starter switch. Should
you choose this option, make certain that you disconnect the purple wire from the coil before turning the key. Protect the
purple wire's connector with electrical tape to avoid accidentally grounding the wire.
5. Prime the oil pump and passages:
a. Crank the engine for approximately 15–18 seconds.
b. Let the starter motor cool down for one minute before cycling again.
c. Repeat this process until the oil pressure registers on an oil pressure gauge. Oil pressure will typically register within
six or seven cycles of cranking and cooling the starter motor.
6. Remove the remote starter switch (or reconnect the purple wire to the ignition coil, if using the boat's key switch).
7. Install the spark plugs and plug wires.
NOTE: Ensure that all plug wires are connected to the proper cylinders and that they are correctly routed. Remove any
temporary labels.
8. Supply the seawater pump with cooling water.
9. Start the engine to verify oil pressure.
Dipstick Installation
1. MCM and MIE TowSport models:
• Reuse the oil dipstick tube from the existing longblock or purchase a new dipstick tube.
• Position the dipstick tube as shown.
2. MIE Inboard models:
• Remove the inboard dipstick assembly from the old engine.
• Install it onto the remanufactured longblock and tighten securely.
• Position the dipstick tube as shown.

Bottom view of engine
a - Proper orientation for dipstick

a

8638
3. MIE Inboard models:
a. Install a bushing, part number 19‑93654, into the dipstick hole on the starboard side of the engine block.

Page 8B-12 © 2019 Mercury Marine 90-8M0149179 eng NOVEMBER 2018