91052-ZW1-003 Honda BEARING ASSY. (Honda Code 4856738).

Introduction
Do not perform any procedure in this Special Instruction until you have read the information and you understand the information.This special instruction will provide the needed tooling and procedure to take valve recession measurements on a C175 engine without removing the valve mechanism components.The depth indicator can be assembled using the components called out in this instruction, or purchased as a set. The indicator should be able to measure between 90 to 105 mm (3.5 to 4.1 inch). The tip of the indicator must be small enough to fit through the bridge oil passage ( 2.0 mm (0.08 inch)).All dimensions are in mm and should be measured and recorded in mm.For consistent readings, always measure stem projection with the cylinder heads torqued to the engine.Required Parts
Table 1
Required Parts
Qty Part Number Part Name
3 3C-3364 Half Nut
1 3P-1565 Clamp
1 5P-4156 Indicator Base
3 8T-4224 Hard Washer
3 9X-6000 Bolt
1 369-2607 Dial Indicator
1 Swiss Precision 21-265-4 or equivalent Stem Drop Indicator Point
1 Starret PT21697-3 or equivalent Drop Indicator Extension
1 FT3339 FT drawing of stand
Illustration 1 g06178343
Stand Assembly
(1) 9X-6000 Bolt
(2) 8T-4224 Hard Washer
(3) 3C-3364 Half Nut
For the FT3339 print, go to https://dealer.cat.com/en/ps/service-tools.html.
Click the "FT Prints" tab.
Click the "FT3300 - FT3399" tab.
Click "FT3339" tab.
Illustration 2 g06178345
Depth Indicator Assembly
(4) 369-2607 Dial Indicator
(5) 3P-1565 Clamp
(6) 5P-4156 Indicator Base
(7) PT21693-2 Drop Indicator Extension
(8) 21-265-4 Stem Drop Indicator PointProcedure
Allow the engine to cool until the valve mechanism is approaching room temperature.
Remove the valve cover.
Place stand on head and tighten three bolts to "hand tight".
Illustration 3 g06178352
(1) Zero hole/tube
Place depth indicator firmly onto stand plate in "Zero" hole/tube.
Illustration 4 g06178353
Run down indicator until the indicator touches. Zero the indicator by pressing "SET" button on the indicator. Spring pressure provides consistent contact on the master surface.
Place the depth indicator into the Intake Inboard (II) slot and run the depth indicator tip through the bridge oil hole and ensure that the tip does not touch the side walls of the 2 mm hole.
Run the probe down until the probe makes solid contact with the top of the valve, while holding the depth indicator firm to the stand plate.
Record the measurement on the check sheet provided at the end of this document.
Repeat Steps 6 through 8 for the Intake Outboard (IO) and Exhaust Outboard (EO).Note: Do not measure the Exhaust Inboard (EI).
Remove stand bolts and repeat Steps 1, 2, 6 through 8 for the remaining cylinder heads
At the same time, while doing projection measurements, the valve lash (intake and exhaust) should be measured/documented and adjusted as needed.
Record and store measurements.Measurement Interpretation
The first measurement is usually 0.0 mm to +0.4 mm
The first measurement should be taken in the first 250 hours.
If the first measurement is taken within the first 4000 hours, the measurement will still be usable to track valve recession over timeFuture measurements will typically be less than the original, as the valve moves upward over time.Future measurement limit: -0.4 mm to 0.0 mm
If the current measurement is -0.4 mm or less than the previous measurement, this head should be monitored closely for valve recession.
If future measurements continue to show a similar linear increase, the head should be planned to be replaced as the measurements approach 2 mm, do not let the measurement reach 2 mm before scheduling the head for replacement.Valve Recession Sample Calculation
Table 2
0 hr 250 hr Recession 500 hr Recession 1K hr Recession 2K hr Recession 3K hr Recession
Cyl #1 Inboard 0.22 0.1 0.12 -0.1 0.32 -0.2 0.42 -0.3 0.52 -0.4 0.62
Outboard 0 0