JOB AID
STUCK INTAKE VALVE
INTRODUCTION
Although a stuck intake valve may occur on any engine, this information is based on the GCV160 engine where the
majority of symptoms have occurred.
The intake valve may stick in the intake valve guide. This most often occurs on:
• Units that are run for short periods of time where the engine doesn’t come to full operating temperature
• Units that are operated in all climate conditions
• Units that are using old or stale fuel
The most likely reason for valve sticking is gasoline "gumming." Gasoline gumming can occur because of the age of the
gasoline, improper storage, and the blend of the gasoline.
There are things your customers can do to prevent this from happening:
• Be sure to use fresh gasoline. As fuel sits in a container, many of the substances will evaporate, causing gumming in
as little as 30 days.
• Store fuel in a larger, red, plastic container that is treated to help prevent the gas from oxidizing and deteriorating
while in storage. Small containers, hot storage areas, and translucent plastic containers cause fuel to deteriorate
more rapidly.
• Follow the storage procedure shown in the owner's manual.
The Distributor's Limited Warranty does not cover fuel system damage or engine performance problems resulting from
improper storage.
The following procedure is for freeing a valve that has been stuck in the open position caused by gum build-up.
PROCEDURE
This procedure was performed on a GCV160 on an HRR216 lawn
mower. Refer to the appropriate shop manual for the model you are
working on.
Tools Required:
• Heat gun rated at 500 degrees (see page 2)
• New Valve Cover (P/N 12310-Z0J-000)
• Hondabond HT Sealant (P/N 08718-0004)
1. Lift the front of the lawn mower (or engine) slightly.
2. Drain the fuel from the fuel tank and carburetor.
3. Referring to the appropriate shop manual, remove the fan cover,
control assembly, carburetor, and insulator.
4. Remove the valve cover.
5. Rotate the engine to just before TDC of the compression stroke.
The cam lobe should be angled about 10 degrees as shown. This
will allow good valve movement, while still preventing the valve
from dropping in the cylinder.
10° BTDC
©2009 American Honda Motor Co., Inc.—All Rights Reserved
Date of Issue: October 2009 (PJA54119)
Page 1 of 2
6. Remove the intake rocker arm, valve retainer, valve
spring, and valve stem seal.
VALVE COVER
VALVE
RETAINER
VALVE
SPRING
VALVE
STEM
SEAL
6 x 12 mm
FLANGE BOLT
INTAKE
ROCKER
SHAFT
INTAKE
ROCKER
ARM
7. Set the heat gun to the 500°F setting and
position it near the intake port as shown.
Do not set the heat gun above 500°F, and be
careful when using the heat gun around
gasoline vapors or residue.
8. Continue using the heat gun, and use a pair of
pliers on the tip of the intake valve stem to
attempt to move the valve. Continue this
process until the valve begins to move (could
take 15 ~ 20 minutes).
9. After the valve begins to move, apply engine oil
to the valve stem groove and continue moving
the valve in and out until it becomes completely
free. The total process could take 30 minutes.
Be patient!
10. Reassemble the valve stem seal, valve spring,
retainer, and rocker arm. Allow the engine to
cool, and adjust the valve clearance.
11. Apply a bead of Hondabond HT sealant to the
new valve cover, and install following the shop
manual procedure.
OIL
PLIERS
INTAKE
VALVE
STEM
INTAKE
PORT
HEAT GUN, ET1400
(Commercially available)
Commercially Available Tool
Description Model Number
Heat Gun ET1400
There are two convenient ways to order: online or by toll-free phone.
• To order online, go to the iN: SERVICE>Tools>Tool and Equipment Program>Online Catalog, and then search by
model number.
• To order by phone, call 1-888-424-6857.
Customer service representatives are available from 7:30 AM until 7:00 PM CT, Monday through Friday.
Page 2 of 2
©2009 American Honda Motor Co., Inc.—All Rights Reserved
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