Acura NSX 1997 Service Manual page 94

Main Menu
Valve Guides
Replacement
1. 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.
IMPACT VALVE GUIDE DRIVER
(Commercially available)
or
VALVE GUIDE DRIVER, 5.5 mm
07742-0010100
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.
Table of Contents
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 head.
VALVE GUIDE DRIVER, 5.5 mm
07742-0010100
If a valve guide still won't move, drill it out with a
8 mm (5/16 inch) 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.