Poppet Valve Replacement - Mercury MerCruiser Service Manual

2. The poppet valve prevents condensation at low speeds.
Poppet Valve Identification
The poppet valve assemblies are color coded to indicate the specific application. The different assemblies use different springs
and have different size orifices. When replacing the poppet valve assembly, refer to the following chart.
Poppet Valve Springs
There are two specific spring pressures that are used to hold the poppet closed, depending on the cooling system type. When
replacing a spring, be certain to order one with the proper spring pressure rating.
NOTE: While springs can be identified by their color when they are new, the color becomes difficult to interpret after the springs
have been in service. Color alone is not a reliable means of identifying the spring pressure rating of a used spring.
Cooling System Type
Standard cooling
Closed cooling
On all models, the poppet valve is connected to the seawater hoses at the top rear of the engine.

Poppet Valve Replacement

Removal
1. Drain the seawater portion of the cooling system.
2. Disconnect the five seawater hoses from the poppet valve assembly.
3. Remove the two screws that secure the poppet valve assembly to the poppet valve bracket. Be certain to retain the J‑clips.
Cleaning and Inspection
NOTE: For parts reference, refer to the preceding exploded view.
1. Remove the two screws from the poppet housing cover to remove the poppet valve subassembly.
2. Carefully remove the pan head screw from the poppet subassembly to inspect the individual components. Inspect the
poppet, spring, relief valve, diaphragm, and O‑rings for debris or damage. Clean or replace parts as necessary.
3. Inspect the poppet valve plate for debris or damage.
4. Inspect the poppet valve housing and inlet fitting for debris or damage. Clean or replace parts as necessary.
NOTE: Remove the two screws from the inlet fitting that hold the two pieces together, if further inspection is necessary.
Installation
NOTE: For parts reference, refer to the preceding exploded view.
1. If the inlet fitting was removed, ensure that the mating surfaces are clean and the O‑ring is in position. Then loosely attach
the two parts with two screws.
IMPORTANT: Poppet valve springs are available in two spring ratings. Be certain to order a spring with the correct rating.
2. Assemble the pieces of the poppet subassembly (poppet, spring, relief valve, diaphragm, washer, and pan head screw).
Tighten the pan head screw to the specified torque.
Description
Pan head screw
3. Ensure that all mating surfaces are clean.
4. Place the O‑ring in the groove on the poppet valve housing.
5. Slide the poppet subassembly into the poppet valve housing.
6. Use two screws to secure the housing cover to the poppet housing.
7. Tighten all screws to the specified torque.
Description
Poppet assembly screws
90-8M0099748 eng DECEMBER 2015
Cooling System Type
Standard cooling
Closed cooling
Drive Type
Bravo
Bravo
Bravo
Drive Type
Color
Stainless steel 1.19 mm (0.047 in.)
Black 1.57 mm (0.062 in.)
Stainless steel 1.19 mm (0.047 in.)
© 2016 Mercury Marine
Bravo
Bravo
Wire Diameter
Nm lb‑in.
2.5 22.1
Nm lb‑in.
8.5 75.2
All Models
Color
Green
Gray
Part Number
90392
64878
90392
lb‑ft
–
lb‑ft
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