1991 ACURA NSX oil pressure

9. Relieve fuel pressure by loosening the service bolt
on the fuel filter about one turn (see section 11).
Do not smoke while working on the
fuel
system.
Keep open flame away from work
area. Drain fuel only into an approved container.
10. Remove the fuel feed pipe and fuel return hose.
11. Remove the wire harness cover, then remove the fuel pipe clamp.

22 N·m
(2.2 kg-m,
16 Ib-ft)

WIRE HARNESS

COVER
6 x 1.0 mm

12 N·m
(1.2 kg-m,

9 lb-ft)

FUEL FEED
PIPE

WASHERS
Replace.

FUEL RETURN

HOSE

12. Remove the brake booster vacuum hose and evapo- rative emission (EVAP) control canister hose.

BRAKE BOOSTER

VACUUM HOSE

EVAP CONTROL

CANISTER HOSE
13. Remove the expansion tank cap.

14. Raise the hoist to full height.
15. Drain the engine coolant (see page
10-5).
Loosen the drain plug from the radiator lower
tank. Remove two drain bolls from the water pipes.
Reinstall the drain bolts with new washers.
Loosen the front and rear engine drain bolts to
drain engine coolant from the cylinder heads.
Connect rubber hoses to the drain bolts.
16. Drain the transmission oil/fluid. Reinstall the drain plug with a new washer.
17. Drain the engine oil. Reinstall the drain plug with a
new washer.

18. Lower the hoist, then remove the air cleaner hous-

ing (see page 6-25 ('91-'93 Mode ls),or('95-'96 Models).

19. Disconnect two hoses, then remove the expansion

tank.

6 x 1.0 mm

10 N·m
11.0 kg-m,

7 lb-ft)

EXPANSION

TANK

WATER BYPASS

HOSES
(cont'd)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

Cylinder Heads

Illustrated Index (cont'd)
CAUTION:
To
avoid
damage,
wait
until
the
engine
coolant
temperature
drops
below
100°F
(39-C]
before
removing
the
cylin-

der head.

NOTE: Use new O-rings and gaskets when reassembling.

Prior to reassembling, clean all the parts in solvent, dry them, and apply lubricant to any contact parts.

REAR VARIABLE VALVE TIMING
AND VALVE LIFT ELECTRONIC CONTROL
SYSTEM (VTEC) SOLENOID VALVE

Troubleshooting, page 6-3 ('91-'93) or ('94-'96)

EXHAUST GAS
RECIRCULATI0N (EGR) VALVE

6 x 1 .0 mm
12 N·m
(1.2 kg-m.
9 Ib-ft)
8 x
1.25
mm

22 N·m
(2.2 kg-m,
16 Ib-ft)
ENGINE COOLANT
TEMPERATURE (ECT) SENSOR
18 N·m (1.8 kg-m, 13 Ib-ft)

8 x
1.25
mm
22 N·m (2.2 kg-m. 16 lb-ft)
FRONT VTEC SOLENOID VALVE

Troubleshooting. page 6-3

SEALING BOLTS

60 N·m
(6.0 kg-m,

43 lb-ft)

OIL PRESSURE

GAUSE SENDING
UNIT (section 23)

ROCKER

SHAFTS
WASHERS
Replace.

8 x
1.25
mm

22 N·m
(2.2 kg-m,16 Ib-ft)
DOWEL PIN

0-RING

Replace.

ECT SWITCH

28 N·m
12.8 kg-m.

20 lb-ft

O-RING

Replace.

O-RING

Replace.

ROCKER ARM ASSEMBLY[PRIMARY. MID, SECONDARY]

Inspection, page 6-32 ('91-'93) or ('94-'96)

ROCKER SHAFT

OIL CONTROL
ORIFICE

Remove with 5 mm

boit and clean.

FILTER
Replace.

GASKET

Replace.

O-RING

Replace.ProCarManuals.com

24. Remove the engine wire harness connectors and
wire harness clamps from the cylinder head and
intake manifold, Six injector connectors
Intake air temperature (IAT) sensor connector
CKP/CYP sensor connector
Heated oxygen sensor (HO2S) connectors

Ignition control module (ICM) connectors

Engine coolant temperature (ECT) sensor connec-

tor

ECT gauge sending unit connector
ECT switch connector
Exhaust gas recirculation (EGR) valve lift sensor

connector

Throttle position sensor connector Engine oil pressure gauge sending unit connector
Knock sensor connector
VTEC solenoid valve connectors
VTEC pressure switch connectors
Engine oil pressure switch connector
Alternator connector

Alternator terminal

Throttle body 6P connector

25. Remove the ignition coils and connector.

26. Remove the EGR pipe and intake manifold assem- bly.

8 x 1.25mm

22 N·m (2.2 kg-m, 16 Ib-ft)

6 x 1.0 mm
12 N·m
(1.2 kg-m,

9 lb-ft)

GASKETS

Replace. INTAKE
MANIFOLD
ASSEMBLY

GASKET
Replace.
27. Loosen the adjusting nut and idler pulley center nut,
then remove the air conditioning compressor belt

(see page 6-17('91-'93) or ('94-'96)).

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

COVER

MOUNTING BOLT
10 x
1.25
mm

45 N·m (4.5 kg·m,

33 Ib-ft)

MOUNTING NUT
10 x
1.25
mm

45 N·m (4.5 kg·m.

33 Ib·ft)
ALTERNATOR

BELT

29. Disconnect the knock sensor connector, then remove
the wire holder.

6 x 1.0 mm
12N·m (1.2 kg-m, 9 Ib-ft)

KNOCK SENSOR
WIRE HOLDER
(cont'd)

6 x 1.0 mm

12 N·m (1.2 kg-m, 9 Ib-ft)

ADJUSTING

BOLTProCarManuals.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

Oil Pressur e
Testing
If th e oi l pressur e warnin g ligh t stay s o n wit h th e engin e
running , chec k th e engin e oi l level . I f th e oi l leve l i s
correct :
1 . Remov e th e engin e oi l pressur e switch , an d instal l
a n oi l pressur e gauge .
2. Star t th e engine . Shu t i t of f immediatel y i f th e
gaug e register s n o oi l pressure . Repai r th e proble m
befor e continuing .
3 . Allo w th e engin e t o reac h operatin g temperatur e
(fa n come s o n a t leas t twice) . Th e pressur e shoul d
be:
Engin e Oi l Pressure :
A t Idle : 7 0 kP a (0. 7 kg/cm2, 1 0 psi )
minimu m
At 3,00 0 rpm : 35 0 kP a (3. 5 kg/cm2, 5 0 psi )
minimu m
• I f oi l pressur e i s
within specifications , replac e th e
oi l pressur e sende r an d recheck .
• I f oi l pressur e i s NO T withi n specifications , inspec t
th e oi l pum p (se e pag e 8-8) .
ENGIN E OI L PRESSUR ESWITCHMOUNTIN G HOL E
OIL PRESSUR E GAUG E ADAPTO R
(1/8 " - 28 , BSPT )
ProCarManuals.com

Expansion Tan k
Cap Testin g
1. Remov e th e expansio n tan k cap , we t it s sea l wit h
engin e coolant , the n instal l i t o n th e pressur e
tester.
2. Appl y a pressur e o f 95-12 5 kP a (0.95-1.2 5
kg/cm2, 14-1 8 psi) .
3 . Chec k fo r a dro p i n pressure .
PRESSUR E TESTE R
ADAPTO R(for 3 2 m m neck )
EXPANSIO N TAN K
CAP
Testin g
1. Wai t unti l th e engin e is cool , the n carefull y remov e
the expansio n tan k ca p an d fil l th e expansio n tan k
with engin e coolan t t o th e to p o f th e fille r neck .
2. Attac h th e pressur e teste r t o th e expansio n tank ,
an d appl y a pressur e o f 9 5 - 12 5 kP a (0.9 5 - 1.2 5
kg/cm
2, 14 - 1 8 psi) .
3 . Inspec t fo r coolan t leak s an d a dro p i n pressure .
4 . Remov e th e tester , an d reinstal l th e expansio n tan k
cap.
NOTE : Chec k fo r engin e oi l i n th e coolan t and/o r
coolan t i n th e engin e oil .
PRESSUR E TESTE R
EXPANSION TAN K
ADAPTO R(for 3 2 m m neck )
ProCarManuals.com