Acura RL (1996-2004 year). Manual — part 337
Valve Guides
Valve Movement
Wobble Method
Measure the guide-to-stem clearance with a dial indica-
tor while rocking the stem in the direction of normal
thrust.
Intake Valve Stem-to-Guide Clearance:
Standard (New): 0.04 - 0.10 mm
(0.002 - 0.004 in)
Service Limit: 0.16 mm (0.006 in)
Exhaust Valve Stem-to-Guide Clearance:
Standard (New): 0.10 - 0.16 mm
(0.004 - 0.006 in)
Service Limit: 0.22 mm (0.009 in)
Valve extended 10 mm out from seat.
If the measurement exceeds the service limit, recheck
using a new valve.
If the measurement is now within the service limit,
reassemble using a new valve.
If the measurement still exceeds the limit, recheck
using the alternate method, then replace the valve
and guide, if necessary.
Alternate Method
An alternate method of checking guide to stem clear-
ance is to subtract the O.D. of the valve stem, measured
with a micrometer, from the I.D. of the valve guide, mea-
sured with an inside micrometer or ball gauge. Take the
measurements in 3 places along the valve stem and
three places inside the valve guide. The difference
between the largest guide measurement and the small-
est stem measurement should not exceed the service
limit.
Intake Valve Stem-to-Guide Clearance:
Standard (New): 0.02 - 0.05 mm
(0.001 - 0.002 in)
Service Limit: 0.08 mm (0.003 in)
Exhaust Valve Stem-to-Guide Clearance:
Standard (New): 0.05 - 0.08 mm
(0.002 - 0.003 in)
Service Limit: 0.11 mm (0.004 in)
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Valve Seats
Reconditioning
1. Renew the valve seats in the cylinder head using a
valve seat cutter.
NOTE: If the guides are worn (see page
),
replace them (see page
) before cutting the
valve seats.
VALVE SEAT
CUTTER
(Commercially available)
2. Carefully cut a 45° seat, removing only enough
material to ensure a smooth and concentric seat.
3. Bevel the upper edge of the seat with the 30° cutter
and the lower edge of the seat with the 60° cutter.
Check the width of the seat and adjust accordingly.
SEAT WIDTH
4. Make one more very light pass with the 45° cutter to
remove any possible burrs caused by the other cut-
ters.
5. After resurfacing the seat, inspect for even valve
seating: Apply Prussian Blue compound to the valve
face, insert the valve in its original location in the
head, then lift it and snap it closed against the seat
several times.
ACTUAL
SEATING
SURFACE
6. The actual valve seating surface, as shown by the
blue compound, should be centered on the seat.
If it is too high (closer to the valve stem), you
must make a second cut with the 60° cutter to
move it down, then one more cut with the 45°
cutter to restore seat width.
If it is too low (closer to the valve edge), you
must make a second cut with the 30° cutter to
move it up, then one more cut with the 45° cutter
to restore seat width.
NOTE: The final cut should always be made with
the 45° cutter.
7. Insert the intake and exhaust valves in the head and
measure valve stem installed height.
8. If valve stem installed height is over the service limit,
replace the valve and recheck. If it is still over the ser-
vice limit, replace the cylinder head; the valve seat in
the head is too deep.
Valve Seat Width:
Standard (New): Intake 0.80 - 1.00 mm
(0.031 - 0.039 in)
Exhaust 1.25-1.55 mm
(0.049 - 0.061 in)
Service Limit: Intake 1.5 mm (0.06 in)
Exhaust 2.0 mm (0.08 in)
Valve Stem Installed Height:
Standard (New): Intake 46.935 - 47.425 mm
(1.8478-1.8671 in)
Exhaust 47.885 - 48.375 mm
(1.8852-1.9045 in)
Service Limit: Intake 47.625 mm (1.8750 in)
Exhaust 48.575 mm (1.9124 in)
VALVE STEM
INSTALLED HEIGHT
VALVE
SEAT
PRUSSIAN BLUE COMPOUND
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Valve Guides
Replacement
As illustrated below, use a commercially available
air-impact valve guide driver attachment modified to
fit the diameter of the valve guides. In most cases,
the same procedure can be done using the special
tool and a conventional hammer.
2. Select the proper replacement guides, and chill them
in the freezer section of a refrigerator for about an hour.
3. Use a hot plate or oven to evenly heat the cylinder
head to 300°F (150°C). Monitor the temperature with
a cooking thermometer.
CAUTION:
Do not use a torch; it may warp the head.
Do not get the head hotter than 300°F (150°C);
excessive heat may loosen the valve seats.
To avoid burns, use heavy gloves when handling
the heated cylinder head.
4. Working from the camshaft side, use the driver and an
air hammer to drive the guide about 2 mm (0.1 in)
towards the combustion chamber. This will knock off
some of the carbon and make removal easier.
CAUTION:
Always wear safety goggles or a face shield
when driving valve guides.
Hold the air hammer directly in line with the
valve guide to prevent damaging the driver.
5. Turn the head over and drive the guide out toward
the camshaft side of the head.
VALVE GUIDE DRIVER, 5.5 mm
If a valve guide still won't move, drill it out with a
8 mm (5/16 in) bit, then try again.
CAUTION: Drill guides only in extreme cases: you
could damage the cylinder head if the guide breaks.
6. Remove the new guides from the freezer, one at a
time, as you need them.
VALVE GUIDE DRIVER
(Commercially available)
5.3 mm
(0.21 in)
10.8 mm
(0.42 in)
57 mm
(2.24 in)
87 mm
(3.43 in)
or
VALVE GUIDE DRIVER, 5.5 mm
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Valve Guides
Replacement (cont'd)
7. Apply a thin coat of clean engine oil to the outside of
the new valve guide. Install the guide from the
camshaft side of the head; use the special tool to
drive the guide in to the specified installed height. If
you have all 12 guides to do, you may have to reheat
the head.
VALVE GUIDE
DRIVER, 5.5 mm
Valve Guide Installed Height:
Intake: 15.75 - 16.25 mm (0.620 - 0.640 in)
Exhaust: 15.75 - 16.25 mm (0.620 - 0.640 in)
VALVE GUIDE
Measure here.
CYLINDER HEAD
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