Section 5 - Maintenance; Positive Crankcase Ventilation Valve (Pcv); Changing; Changing The Water-Separating Fuel Filter - Mercury MerCruiser 4.3 TKS User Manual

Table of Contents

Positive Crankcase Ventilation Valve (PCV)

CHANGING

IMPORTANT: Use only Mercury MerCruiser replacement parts to ensure compliance with

emission regulations.

NOTE: On V6 models the PCV valve is non‑serviceable and is an internal component of

the valve cover.

1. Remove the PCV valve from the port valve cover.

2. Disconnect the PCV valve from the hose and discard the valve.

3. Install a new PCV valve in the valve cover and reconnect the hose.

4. Ensure the PCV valve is tightly seated in the valve cover.

Changing the Water‑Separating Fuel Filter

Fuel is flammable and explosive. Ensure the key switch is off and the lanyard is positioned

so that the engine cannot start. Do not smoke or allow sources of spark or open flame in

the area while servicing. Keep the work area well ventilated and avoid prolonged

exposure to vapors. Always check for leaks before attempting to start the engine and

wipe up any spilled fuel immediately.

1. Allow the engine to cool down.

NOTE: Mercury MerCruiser recommends that the engine be shut off for 12 hours prior to

filter removal.

2. Close fuel supply valve, if equipped.

3. Wrap the water separating fuel filter with a cloth to help catch any fuel spills or spray.

4. Remove and discard the water separating fuel filter and sealing ring from the mounting

bracket.

5. Coat the sealing ring on the new filter with engine oil.

Tube Ref. No.

90-899883179 OCTOBER 2007

a -

PCV valve

Description

Synthetic Blend MerCruiser Engine

Oil SAE25W‑40

mc71925-1

b -

Hose

WARNING

Where Used

Filter sealing ring