1991 ACURA NSX Service Repair Manual

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
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Removal

NOTE:
Before removing the belt, turn the crankshaft pulley
so the No. 8 piston is at top dead center (TDC) (see
page 6-19 ('91-'93) or ('94-'96)

Inspect the water pump after removing the timing
belt (see page 10-11).

If it is to be reused, mark the direction of rotation on

the belt.
1. Disconnect the battery negative terminal first, then the positive terminal,
2. Remove the right rear wheel/tire.
3. Remove the engine oil cooler base assembly- NOTE: Do not disconnect the hoses.

O-RING

Replace.

8 x
1.25
mm

22 N·m
(2.2 kg-m,
16 Ib-ft)

8 x
1.25
mm

22 N·m
(2.2 kg-m,

16 Ib-ft)

Replace.

4. Remove the strut brace (see page 5-3 ('91-'93) or ('94-'96)

5. Remove the intake manifold plate and top cover (see

page 6-25 ('91-'93) or ('94-'96)

4. Remove the ignition coil covers, the injector cover
and the wire harness covers.
5. Remove the ignition coils and the connectors.
NOTE:
There are front and rear ignition coils and covers.
They can be identified by the mark FF (front) orRR (rear) printed on them.
When installing front and rear ignition coil covers,
attach a rubber seal to the intake side.

6 x 1.0 mm

12 N·m
(1.2 kg-m,

9 Ib-ft)
IGNITION COIL

COVER

6 x 1.0 mm

10 N·m
(1.0 kg-m,

7 Ib-ft)

HARNESS

COVERS

6 x 1.0 mm
12 N·m
(1.2 kg-m,

9 Ib-ft)

CONNECTOR

IGNITION COIL

6. Remove the expansion tank.
NOTE: Do not disconnect water hoses.

6 x 1.0 mm
10 N·m (1.0 kg-m, 7 Ib-ft)

EXPANSION TANK

(cont'd)ProCarManuals.com

Timing Belt

Removal (cont'd)

7. Remove the breather hose and the air cleaner hous-
in
g
(see page 6-25 ('91-'93) or ('94-'96) )

8. Disconnect the alternator connector and the termi-

nal.

9. Remove the cover, adjusting bolt, the mounting bolt and mounting nut, then remove the alternator belt
and the alternator.

COVER

6 x 1.0 mm

12 N·m
(1,2 kg-m,

9 Ib-ft)

MOUNTING BOLT
10 x 1.25 mm

45 N·m
(4.5 kg-m,

33 Ib-ft)

ADJUSTING

BOLT

MOUNTING NUT
10 x
1.25
mm

45 N·m
(4.5 kg-m,

33 Ib-ft)
ALTERNATOR

BELT

10. Remove the cylinder head covers.

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

11. Remove the two bolts from the side engine mount
near the alternator bracket. Pivot the mounting bracket

into the housing of the body.

12 x 1.25 mm

73 N·m (7.3 kg-m, 53 Ib-ft)

Replace.

12 x
1.25
mm

95 N·tn (9,5 kg-m,
69 Ib-ft)
CORROSION RESISTANT BOLT

12. Remove the transmission mount (see page 5-10 ('91-'93)
or ('94-'96) transmission mount

13. Install a brace under the engine, then tilt the engine
approximately 5 using a jack.

NOTE: Make sure to place a cushion between the

oil pan and the jack.

14. Remove the alternator bracket stiffener and dipstic
pipe.

ALTERNATOR BRACKET
STIFFENER

8 x
1.25
mm
22N·m

(2.2 kg-m,
16 lb-ft!

10 x
1.25
mm

45 N·m
(4.5 kg-m,

33 Ib-ft!
6 x 1.0 mm

12N·m (1.2 kg-m, 9 Ib-ft)
DIPSTICK PIPProCarManuals.com

15. Loosen the idler pulley center nut and adjusting nut,

then remove the air conditioning (A/C) compressor
belt.

IDLER PULLEY
CENTER NUT

45 N·m
(4.5 kg-m,

33 lb-ft)

ADJUSTING

NUT

A/C COMPRESSOR

BELT

16. Remove the crankshaft pulley (see page 6-12 ('91-'93)
or ('94-'96)

17. Remove the rubber seal from the adjusting bolt,
then remove the middle covers and lower cover.

6 x 1.0 mm

12 N·m
(1.2 kg-m.

9 Ib-ft)
LOWER COVER RUBBER SEAL
6 x 1.0 mm
12 N·m
(1.2 kg-m,

9 lb-ft)

9 x
1.25
mm

22 N·m
(2.2 kg-m,

16 Ib ft)
IDLER PULLEY
ASSEMBLYCOLLAR
MIDDLE COVER
18. Loosen the adjusting boll 180
0
turn. Push the ten-

sioner to remove tension from the timing belt, then
re tighten the adjusting bolt.

ADJUSTING BOLT
Do not remove. When
adjusting, loosen

it
180°.

19. Remove the timing belt from the pulleys.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

6. Adjust the timing belt (see page 6-14 ('91-'93) or ('94-'96))

7. Install the lower cover and middle covers.

8. Install the crankshaft pulley, then tighten the pulley

bolt (see page 6-12 ('91-'93) or ('94-'96))
9. Check the crankshaft pulley and the camshaft pul- leys at TDC.
NOTE: To check the camshaft, try to insert 5.0 mm
pin punches as shown when the camshaft is at TDC.

TDC MARK
(White paint)
TDC MARK

FRONT:
TDC MARKS

5.0 mm

PIN PUNCHES BACK COVER
MIDDLE COVER
REAR: TDC MARK

5.0 mm

PIN PUNCHES
TDC MARK
MIDDLE COVER

TDC MARKS
10. If a camshaft is not positioned at TDC, remove the

timing belt and adjust the positioning following the

procedure on page 6-18 ('91-'93) or ('94-'96) then reinstall

the timing belt.

11. After installation, adjust the tension of each belt.
See section 23 for alternator belt tension adjust-

ment.

See section 22 for A/C compressor belt tension
adjustment.ProCarManuals.com

CKP/CYP Sensor

Replacement

NOTE: Turn the crankshaft so fhat the No. 1 piston is at
top dead center (see page 6-19 ('91-'93) or ('94-'96))
1. Remove the timing belt (see page
6-15 ('91-'93) or ('94-'96)

2. Remove the front intake end exhaust camshaft
pulleys.
3. Remove the back cover.
4. Remove the CKP/CYP sensor from the front
cylinder head.
5. Install the CKP/CYP sensor in the reverse order of
removal.

Refer to page 6-18 ('91-'93) or ('94-'96) and 19 when

('91-'93) or ('94-'96) installing thetiming belt.

10 x
1.25
mm

70 N·m
(7.0 kg-m,

51 Ib-ft)

6 x 1.0 mm
12N·m II.2 kg-m,

9 Ib-ft) FRONT INTAKE
CAMSHAFT PULLEY

CKP/CYP

SENSOR

FRONT

CAMSHAFTS

TIMING
BELT

FRONT EXHAUST
CAMSHAFT PULLEY

10 x
1.25
mm

70 N·m
(7.0 kg-m,

61 Ib-ft)

BACK

COVER

MIDDLE COVER

6 x 1.0 mm
12N·m (1.2 kg-m.

9 Ib-ft)
LOWER COVERProCarManuals.com

Cylinder Head s
Illustrate d Inde x
CAUTION : T o avoi d damage , wai t unti l th e engin e coolan t temperatur e drop s belo w 100° F (38°C ) befor e removin g th e cylin -
de r head .
NOTE : Us e ne w O-ring s an d gasket s whe n reassembling .
Prio r t o reassembling , clea n al l th e part s i n solvent , dr y them , an d appl y lubrican t t o an y contac t parts .
6 x 1. 0 m m10N- m (1.0 kg-m ,7 Ib-ft )
CAMSHAF T HOLDE R
DOWE L PI N
O-RIN G
Replace . CAMSHAF
T HOLDE R
PLATE
6 x 1. 0 m m12N- m (1.2 kg-m ,9 Ib-ft ) CKP/CY
P SENSO R
6 x 1. 0 m m12N- m (1.2 kg-m ,9 Ib-ft )
RUBBE R SEAL S
Replac e whe n damage dor deteriorated .
BACK COVE R
8 x 1.2 5 mm22N- m (2. 2 kg-m , 1 6 Ib-ft )Apply oi l t o th e bol t threads .
FRONT INTAK ECAMSHAF T
RUBBER SEAL S
Replac e fo r oi l
leakage .
FRON T EXHAUS T
CAMSHAF T
DOWEL PI N
CAMSHAF T PULLE Y
OI
L SEA L
Replace .
DOWE
L PI N
10 x 1.2 5 mm70N- m (7. 0 kg-m ,51 Ib-ft )
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