1991 ACURA NSX clock

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

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

Timing Belt

Inspection

1. Remove the ignition coil covers and harness clamps.
2. Disconnect the connectors, then remove the ignition
coils.
3. Remove the cylinder head covers,
4. Inspect the timing belt for cracks and coolant or oil soaking.

NOTE:
Replace the belt if coolant or oil soaked.
Remove any oil or solvent that gets on the belt.

Inspect this area

for wear.

Rotate pulley and

Inspect belt.
Tension Adjustment

CAUTION:
Always adjust timing belt tension with the engine cold
Do not rotate the crankshaft when the adjusting bolt
is loose (the timing belt will skid over the teeth of
the rear intake caimshaft pulley).
Adjust the belt tension only when the belt has been
removed and reinstalled or replaced.

NOTE:
Tensioner is spring-loaded to apply proper tension to
the belt automatically after making the following ad-
justment. Inspect the timing belt before adjusting the belt
tension.
Always rotate the crankshaft clockwise. Rotating it
counterclockwise may result in improper adjustment
of the belt tension or cause the belt to jump a tooth
on the camshaft pulleys.
Install the timing beIt with the No. 1 piston at TDC
(see pages 6-18 ('91-'93) or ('94-'96),19 ('91-'93)
or ('94-'96) Remove the slack in the sequence of , and

by turning each camshaft pulley slightly.
Loosen the timing belt adjusting bolt 180° (the slack
at should be eliminated).

Then, tighten the timing belt adjusting bolt.

Verify that No. 1 piston is at TDC (see page 6-19).
Rotate the crankshaft clockwise nine teeth on the
camshaft pulley (The blue mark on the crankshaft pul- ley should line up with the pointer on lower cover).
Loosen
the
timing
belt
adjusting
bolt.

Retighten the adjusting bolt, torque to 43 N·m (4.3
kg-m, 31 Ib-fl).
Direction

of rotation

POINTER ON
LOWER COVER

ADJUSTING BOLT

43N·m (4.3 kg-m,

31 Ib-ft)
BLUE MARK
TDC MARK
ProCarManuals.com

Timing Belt

Installation

Install the timing belt in the reverse order of removal;

Only key points are described here.

NOTE: Clean the middle and lower covers before instal-

lation.

1. Set the timing belt drive pulley so that the No. 1 pis-

ton is at top dead center (TDC). Align the mark on

the teeth side of the timing belt drive pulley to the

pointer on the oil pump.

POINTER

MARK

KEY

TIMING BELT

DRIVE PULLEY

Clean.

2. Set the front camshaft pulleys so that the No. 1 pis-

ton is at TDC. Align the TDC marks on the front

exhaust camshaft pulley and front intake camshaft

pulley to the pointer on the back cover.

Pointer on the

back cover.

FRONT INTAKE

CAMSHAFT PULLEY
FRONT EXHAUST

CAMSHAFT PULLEY

TDC MARKS
3. Set the rear camshaft pulleys so that the No. 1 pis-

ton is at TDC. Align the TDC mark on the rear intake

camshaft pulley to the pointer on the back cover.

Align the rear exhaust camshaft pulley one half

tooth clockwise past TDC.

REAR EXHAUST

CAMSHAFT PULLEY
Pointer on the

back cover.
REAR INTAKE

CAMSHAFT PULLEY

TDC MARKS

4. Install the timing belt tightly in the sequence shown.

Timing belt drive pulley (crankshaft)

Adjusting pulley Front exhaust camshaft pulley

Front intake camshaft pulley Water pump

pulley Rear intake camshaft pulley Rear

exhaust camshaft pulley.

NOTE: Make sure the timing belt drive pulley and

camshaft pulleys are at TDC.

5. Tension the timing belt between the pulleys in the

sequence A to E as shown below.ProCarManuals.com

Reaming
NOTE: Fo r ne w valv e guide s only .
1 . Coa t bot h reame r an d valv e guid e wit h cuttin g oil .
2 . Rotat e th e reame r clockwis e th e ful l lengt h o f th e
valv e guid e bore .
3 . Continu e t o rotat e th e reame r clockwis e whil e
removin g i t fro m th e bore .
4 . Thoroughl y was h th e guid e i n detergen t an d wate r
t o remov e an y cuttin g residue .
5 . Chec k clearanc e wit h a valv e (se e pag e 6-39 ).
— Verif y tha t th e valv e slide s in th e intak e an d exhaus t
valv e guide s withou t exertin g pressure .
VALVE GUID E
REAMER , 5. 5 m m
07HAH-PJ7010 B
ProCarManuals.com

28. Tighten bolts and nuts finger tight at six points as

shown below.

29. Starting with nut torque all bolts and nuts, in a

clockwise pattern in three steps.

NOTE: Excessive tightening can cause distortion of

oil pan gasket and oil leakage.

Torque: 14 N-m (1.4 kg-m, 10 lb-ft)ProCarManuals.com

Inspection


Replacement
1. Remove the timing belt (see page 6-15) ('91-'93) or

('94-'96).

2. Check that the water pump pulley turns counterclock-

wise.

3. Check for signs of seal leakage.
NOTE: A small amount of "weeping" from the bleed
hole is normal.

Turns
counterclockwise

BLEED HOLE
BLEED HOLE

1. Remove the timing belt (see page 6-15 ('91-'93) or
('94-'96).

2. Unscrew the bolts, then remove the water pump.
NOTE: Inspect and clean the 0-ring groove and
mating surface with the cylinder block.

DOWEL PIN
SPECIAL BOLTS
6 x 1.0 mm: 7 BOLTS
12 N·m

(1 .2 kg-m, 9 Ib-ft)

Replace,

WATER PUMP
0-RING

Replace.
SPECIAL BOLTS
8 x 1.25 mm: 2 BOLTS

22 N·m
(2.2 kg-m,
16 Ib-ft)
Replace.

3. Install the water pump in the reverse order of
removal.

NOTE:
Keep the 0-ring in position when installing.
Clean up spilled engine coolant.ProCarManuals.com

II. Engine Control Module (ECM) Reset Procedure

Either of the following actions, will reset the ECM.

• Using the OBD-II scan tool or Honda PGM Tester to clear the ECM's memory.

NOTE: See the OBD-II scan tool or Honda PGM Tester user's manuals for specific operating instructions.

• Turn the ignition switch OFF. Remove the CLOCK (7.5 A) fuse from the under-hood fuse/relay box for 10 seconds.

UNDER-HOOD

FUSE/RELAY BOX
CLOCK

(7.5 A) FUSE

III. Final Procedure (this procedure must be done after any troubleshooting)

1. Remove the SCS Service Connector if it is connected.

NOTE: If the SCS service connector is connected and there are no DTCs stored in the ECM, the MIL will stay on

when the ignition switch is turned on.

2. Do the ECM Reset Procedure.

3. Turn the ignition switch OFF.

4. Disconnect the OBD-II scan tool or Honda PGM Tester from the Data Link Connector,ProCarManuals.com