1991 ACURA NSX Service Repair Manual

Special Tools

Ref.
No.

Tool Number

07HAH—-PJ7010B

07JAA—001020A

07JAB—001020A

07MAA—PR70110

07MAA—PR70120

07MAF—PR9010A

07MAJ—PR7020A

07NAB—001030A

07NAB — 001040A

07742—0010100

07757—-PJ1010A
Description

Valve Guide Reamer, 5.5 mm
Socket, 19 mm Holder Handle
Tappet Adjuster
Tappet Locknut Wrench Valve Spring Compressor Attachment
Extension

VTEC Plug

Holder Attachment, 45 mm
Holder Attachment, 50 mm
Valve Guide Driver, 5.5 mm
Valve Spring Compressor Attachment
Qty

1

1
1
1
1

1
1
1
1
1

1
Page Reference

6-41 ('91-'93) or
('94-'96 Models).

6-12 ('91-'93) or
('94-'96 Models).
6-12 ('91-'93) or
('94-'96 Models).
6-10 ('91-'93) or
('94-'96 Models).
6-10 ('91-'93) or
('94-'96 Models).
6-36('91-'93)or
('94-'96 Models).

6-7,8('91-'93) or
('94-'96 Models).

6-12 ('91-'93) or
('94-'96 Models).

6-12 ('91-'93) or
('94-'96 Models).

6-40 or 41('91-'93) or
('94-'96 Models).
6-36 ('91-'93)or ('94-'96 Models).
ProCarManuals.com

VTEC
VTEC Solenoi d Valv e Inspectio n
1. Disconnec t th e 2 P connecto r fro m th e VTE C sole -
noi d valve .
2 . Measur e resistanc e betwee n th e BLU/YE L (front/rear )
terminal s an d bod y ground .
Resistance : appro x 1 4 - 3 0 ohm s
BLU/YE L
3. I f th e resistanc e i s withi n specifications , remov e th e
VTE C solenoi d valv e fro m th e cylinde r head , an d
chec k th e VTE C solenoi d valv e filte r fo r clogging .
• I f ther e i s clogging , replac e th e engin e oi l filte r
an d engin e oil .
VTE C SOLENOI D VALV E
VTE C SOLENOI D VALV E
FILTER/O-RIN G
Replace.
6 x 1. 0 m m12 N- m (1. 2 kg-m , 9 Ib-ft )
4. I f th e filte r i s no t clogged , pus h th e VTE C solenoi d
valv e wit h you r finge r an d chec k it s movement .
• I f VTE C solenoi d valv e is normal , chec k th e engin e
oi l pressure .
6 x 1. 0 m m12 N- m (1. 2 kg-m , 9 Ib-ft )
ProCarManuals.com

Rocker Arms


Manual Inspection

1. Remove the ignition coil covers (see page 6-15 ('91-'93) or ('94-'96)
2. Remove the ignition coils (see page 6-15 ('91-'93)or ('94-'96).

3. Remove the cylinder head covers.

NOTE: Refer to pages 6-47 ('91-'93)
or ('94-'96) ,48 ('91-'93)

or ('94-'96) when installing the cylinder head cover.

4. Set the No. 1 piston at top dead center (TDC) (see

page 6-19 ('91-'93)
or ('94-'96).
5. Push the mid rocker arms on the No. 1 cylinder man-

ually.

6. Check that the mid rocker arms move independently
of the primary and secondary rocker arms.

MID ROCKER

ARM
SECONDARY

ROCKER ARM

PRIMARY

ROCKER ARM

7. Check the mid rocker arms of each cylinder at TDC. If a mid rocker arm does not move, remove the

mid, primary and secondary rocker arms as an

assembly and check that the pistons in the mid
and primary rocker arms move smoothly.
Replace the rocker arms as an assembly if there
is any abnormality. Rocker Arms


Inspection Using

Special Tools

CAUTION:
Before using the special tool, make sure that the air
pressure gauge on the air compressor indicates over
250 kPa (2.5 kg/cm2. 36 psi). Inspect the valve clearance before rocker arm inspec-

tion.

Cover the timing belt with a shop towel to prevent

getting oil on the belt.

Check the mid rocker arms of each cylinder at TDC.

1. Plug the relief hole with the special tool as shown.

Front cylinder head:

RELIEF HOLE

VTEC PLUG

07MAJ–PR7020A

VTEC INSPECTION HOLE

SEALING BOLT

Rear cylinder head:

RELIEF HOLE
VTEC PLUG

07MAJ–PR7020A

VTEC INSPECTION HOLE

SEALING BOLT
(cont'd)ProCarManuals.com

Valve Clearance

Adjustment

NOTE:
Valves should be adjusted cold, when the cylinderhead temperature is less than 100°F (38°C).
Adjustment is the same for both intake and exhaust valves.
Adjust valve clearance at TDC of each cylinder.
Do not rotate the engine counterclockwise. The tim-
ing belt could jump a tooth on the camshaft pulleys.

1. Remove the cylinder head covers.
NOTE: Refer to pages 6-47 ('91-'93),or ('94-'96), 6-48
('91-'93), or ('94-'96) when installing the cylinder head cover.

FRONT:

No.6 No.5 No.4
EXHAUST

INTAKE

No.6 No.5 No.4

REAR:
No.3 No.2 No.1

INTAKE

EXHAUST

No.3 No.2 No.1 (cont'd)

CRANKSHAFT PULLEY
TDC MARK (WHITE PAINT)
POINTER ON

THE LOWER

COVER

REAR:

Number 1 PISTON at TDC

FRONT:

2. Rotate the crankshaft to set No. 1 piston at TDC.
TDC mark (white paint) on the crankshaft pulley
should align with pointer on the timing lower
cover, and TDC grooves on the camshaft pulleysshould align with timing belt cover plates.ProCarManuals.com

Valve Clearance
Adjustment (cont'd)
3. Manually inspect the rocket arms for independentoperation (see page 6-7, 8 ('94-'96), 6-36, 37 ('91-'93).
4. Adjust valves on No.1 cylinder.
• Adjusting screws are on primary and secondary
rocker arms,

Intake: 0.15-0.19 mm (0.006-0.007 in)

Exhaust: 0.17-0.21 mm (0.007-0.008 in)

5. Loosen the locknut, and turn the adjustment screw
until the feeler gauge slides back and forth with a

slight amount of drag.

INTAKE:
TAPPET ADJUSTER

07MAA–PR70110
FEELER

GAUGE

TAPPET LOCKNUT

WRENCH

07MAA–PR70120

EXHAUST: NOTE: Use a mirror to check if the special tool is

positioned on the locknut correctly.

FEELER

GAUGE
6. Tighten the locknut and check the clearance again.
Repeat adjustment if necessary.

INTAKE:
FEELER

GAUGE
LOCKNUT

7 x

0.75
mm

20 N·m
(2.0
kg-m.
14 Ib-ft)

EXHAUST:
FEELER

GAUGE
LOCKNUT

7
x

0.75
mm

20 N·m
(2.0
kg-m,

14 Ib-ft)ProCarManuals.com

7. Rotate the crankshaft 120° clockwise (camshaft pulley

turns 60°). Check that the front intake camshaft pulley

is positioned as shown.

Repeat step 3 to step 6.

Number 4 piston at TDC:

8. Rotate the crankshaft 120° clockwise (camshaft pulley

turns 60°). Check that the front intake camshaft pulley

is positioned as shown.

Repeat step 3 to step 6.

Number 2 piston at TDC:

9. Rotate the crankshaft 120° clockwise (camshaft pulley

turns 60°). Check that the front intake camshaft pulley

is positioned as shown.

Repeat step 3 to step 6.

Number 5 piston at TDC:
10. Rotate the crankshaft 120° clockwise (camshaft pulley

turns 60°). Check that the front intake camshaft pulley

is positioned as shown.

Repeat step 3 to step 6.

Number 3 piston at TDC:

11. Rotate the crankshaft 120° clockwise (camshaft pulley

turns 60°). Check that the front intake camshaft pulley

is positioned as shown.

Repeat step 3 to step 6.

Number 6 piston at TDC:ProCarManuals.com

Crankshaft Pulle y an d Pulle y Bol t
Replacemen t
When installin g an d tightenin g th e pulley , follo w th e procedur e below .
Clean , remov e an y oi l an d lubricat e point s show n below .
Clean
Remov e an y oi l
Lubricat e
CRANKSHAF TPULLEY
WASHE R
PULLEY BOL T
TIMIN G BEL TDRIV E PULLE YCRANKSHAF T
TIMING BEL TGUID E PLAT ETIMING BEL T
GUID E PLAT E
Crankshaf t pulle y bol t siz e an d torqu e value :
16 x 1. 5 m m
250 N- m (25. 0 kg-m , 18 1 Ib-ft )
NOTE :
• D o no t us e a n impac t wrenc h whe n installing .
• Mak e sur e th e handl e thum b scre w align s wit h th e hol e i n th e attachment .
HOLDER HANDL E07JAB - 001020 A
M/T: HOLDE R ATTACHMENT , 4 5 m m
07NA B - 001030 A
A/T : HOLDE R ATTACHMENT , 5 0 m m
07NA B - 001040 A
TORQU E WRENC H
SOCKET, 1 9 m m
07JA A - 001020 A
o r (Commerciall y available )
ProCarManuals.com

Timing Belt
Illustrated Index
NOTE:
Refer to page 6-18 ('91-'93) or ('94-'96) for positioning crankshaft and pulley before installing the belt.

if it is to be reused, mark the direction of rotation on the belt before removing.

Do not use the middle cover and lower cover for storing removed items.

Clean the middle cover and lower cover before installing.

Replace the camshaft seals and crankshaft seals if there is oil leakage.

Refer to page 6-12 ('91-'93) or ('94-'96) before installing timing belt.

CYLINDER HEAD COVER

Refer to page 6-47 ('91-'93) or ('94-'96)

when installing

RUBBER SEALS
Replace when damaged
or deteriorated.

6 x 1.0 mm
12N·m (1.2 kg-m,

9 Ib-ft)

6 x 1.0 mm
12N·m (1.2 kg-m.

9 Ib-ft)

MIDDLE

COVER

RUBBER SEALS

Replace when damaged
or deteriorated.

LOWER COVER

6 x 1.0 mm

12 N·m
(1.2
kg-m,

9 Ib-ft)

CRANKSHAFT
PULLEY

Replacement,

page 6-12 ('91-'93) or ('94-'96)

PULLEY BOLT

16x 1.5 mm

250 N·m
(25.0 kg-m. 181 Ib-ft)

Replacement,

page 6-12 ('91-'93)
or ('94-'96)

Do not use an impact

wrench when installing.
HEAD COVER GASKET

Replace when leaking,
damaged or deteriorated.
Apply liquid gasket at
the eight corners of the

ecesses
CAP NUT

6 x 1.0 mm

10N m (1.0 kg-m,

7 Ib-ft)

WASHERS
Replace when damaged
or deteriorated.

RUBBER SEALS

Replace when damaged
or deteriorated.
ADJUSTING BOLT
10 x
1.25
mm

43N.m (4.3 kg-m.31 Ib-ft)

For adjustment only,

do not remove.

COLLARS
TIMING BELTInspection, page 6-14 ('91-'93) or ('94-'96)

Adjustment, page 6-14 ('91-'93) or ('94-'96)

Install with concave

surface facing out.

6 x 1.0 mm
12N·m (1.2 kg-m, 9 Ib-ft)ProCarManuals.com