1991 ACURA NSX drain bolt

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

Cylinder Heads

Removal

Engine removal is not required for this procedure. Make sure jacks and safety stands are
placed properly and hoist brackets ere attached to cor- rect positions on the engine.
CAUTION: Use a fender cover (special tool) to avoid damaging
painted surfaces. Unplug the wiring connectors carefully while holding
the connector portion to avoid damage.
To avoid damaging the cylinder heads, wait until the
engine coolant temperature drops below 100°F
(38°C) before loosening the retaining bolts. Do not open the engine cover when the roof panel is
stored (NSX-T open top).
NOTE:
Unspecified items are common.

Mark all wiring and hoses to avoid misconnection.
Also, be sure that they do not contact other wiring or

hoses or interfere with other parts.

Inspect the timing belt before removing the cylinder

head.

Turn the crankshaft pulley SO that the No. 1 piston is at top dead center (see page 6-19 ('91-'93) or ('94-'96)).
1. Disconnect the negative terminal from the battery.
2. Remove the expansion tank cap. Use care when removing the expan-
sion tank cap to avoid scalding by engine coolant
or steam.
3. Raise the car, then remove the right rear wheel/tire.
4. Drain the engine coolant (see page 10-5 ). 5. Remove the engine under guard, then remove the
front exhaust pipe A.

GASKETS
Replace.

FRONT EXHAUST

PIPE A

SELF-LOCKING NUT

10 x
1.25
mm

55 N·m (5.5 kg-m, 40 Ib-ft)
Replace.
SELF- LOCKING NUT

8 x
1.25
mm

22 N·m (2.2 kg-m. 16 Ib-ft)

Replace.

6. Remove the rear exhaust pipe A.

SELF- LOCKING NUT

8 x
1.25
mm
22 N·m (2.2 kg-m, 16 Ib-ft)

Replace.

REAR

EXHAUST

PIPE A

SELF-LOCKING NUT
10 x
1.25
mm

55 N·m (5.5 kg-m.

40 Ib-ft)

Replace.
GASKETS

Replace.

7. Remove the engine oil cooler base assembly (see
page 6-15 ('91-'93) or ('94-'96).

8. Lower the car.
9. Remove the strut brace (see page 5-3 ).ProCarManuals.com

10. Remove the engine cover stay from the strut brace,
then set the engine cover stay between the engine
cover and rear hatch latch (NSX-T open top),
CAUTION: Use a shop tower to avoid damaging

painted surfaces.

SHOP

TOWEL

11. Relieve fuel pressure by loosening the service bolt on the fuel filter about one turn (see section 11).
Do not smok* while working on fuel
system; Keep open flame or spark away from work

area. Drain fue1 only into an approved container.

12. Remove the fuel feed pipe and fuel return hose (see page 5-5 ('91-'93) or ('94-'96).

13. Remove the evaporative emission (EVAP) control
canister hose and brake booster vacuum hose (see
page 5-5 ('91-'93) or ('94-'96).
14. Disconnect the breather pipe and vacuum hose, then remove the air cleaner housing.

6 x 1.0 mm

10 N·m (1.0 kg-m, 7 lb-ftl

AIR CLEANER
HOUSING

BREATHER

PIPE

: CORROSION RESISTANT BOLT
15. Remove the Hoses, then remove the expansion tank
(see page 5-5 ('91-'93) or ('94-'96).
16. Removel the radiator hoses and heater hose (see
page 5-6 ('91-'93) or ('94-'96).

17. Disconnect the two connectors, then remove the
control box (see page 5-6 ('91-'93) or ('94-'96).

18. Remove the intake manifold plate and top cover.

INTAKE MANIFOLD

PLATE
6 x
1.0mm

12 N·m (12kg-m,

9 lb-ft)

TOP COVER

19. Remove the fuel injector covers.
6 x 1.0 mm
12 N·m (1-2 kg-m, 9 lb-ft)

FUEL INJECTOR

COVER

(cont'd)

ENGINE

COVER

STAYProCarManuals.com

Oil Pump
Removal/lnspection/lnstallation
1. Drain the engine oil. 2. Remove the timing belt (see page 6-15('91-'93)or('94-'96)).
3. Remove the dipstick and the pipe.
4. Remove the oil filter assembly.
5. Remove the oil pan.
6. Remove the oil screen.
7. Remove the baffle plate,
8. Remove the oil pass
pipe and the joint.
9. Remove the mounting bolts and the oil pump

assembly.

Replace.
O-RINGS
Replace.

OIL SCREEN OIL PASS PIPE

AND JOINT
BAFFLE PLATE

OIL PUMP
10. Remove the nine screws from the pump housing,

then separate the housing and cover.

11. Check the inner-to-outer rotor radial clearance.

Inner-to-Outer Rotor Radial Clearance
Standard (New): 0.05 – 0.21 mm (0.002 – 0.008 in)
Service Limit: 0.23 mm (0.009 in)

OUTER ROTOR

INNER ROTOR

12. Check the housing-to-rotor axial clearance. Housing-to-Rotor Axial Clearance
Standard (New): 0.02 – 0.07 mm
(0.001 – 0.003 in)

Service Limit: 0.12 mm (0.005 in)

PUMP HOUSING

OUTER ROTORProCarManuals.com

Engine Coolant Refilling and Bleeding

CAUTION: When pouring engine coolant, be sure to

shut the relay box lid and not let coolant spill on the

electrical parts or the paint. If any coolant spills, rinse it

off immediately.

NOTE:

• Perform this maintenance when the engine is cool.

• Before replacing the coolant, turn the ignition ON,

slowly turn the climate control temperature knob to

90° and turn off the ignition. This will allow the

coolant in the heater to drain out with the rest of the

system.
1. Open the hood, the rear window and the engine

cover.

2. Remove the cover protecting the water pipes and

shift cables on the underside of the car.

3. Before removing the expansion tank cap, first

loosen the cap to lower pressure.

CAUTION: Do not remove the expansion tank cap

when engine is hot. The coolant is under pressure

and may blow out and scald you. Open the cap

slowly when the engine is cool.

4. Loosen the drain plug in the bottom of the radiator,

and drain the coolant.

5. Remove the two drain bolts from the water pipes,

and drain the coolant.

WASHERS

Replace.

DRAIN BOLTS

15 N-m (1.5 kg-m, 11 Ib-ft)
DRAIN HOLE
DRAIN PLUGProCarManuals.com

Radiator
Engine Coolan t Refillin g an d Bleedin g
6. Instal l rubbe r hose s o n th e drai n bolt s a t th e fron t
an d rea r of the engin e unde r th e cylinde r banks .
Loose n th e drai n bolt s t o drai n th e coolant .
• Drainin g ca n b e don e mor e quickl y i f al l th e blee d
bolt s an d plu g ar e als o opened . Befor e openin g
them , mak e sur e th e coolan t leve l i n th e expan -
sio n tan k ha s com e dow n completel y s o tha t th e
coolan t wil l no t pou r ou t o f th e blee d bolt s an d
plug .
7. Whe n th e coolan t stop s draining , tighte n th e
radiato r drai n plug , wate r pip e drai n bolt s an d
engin e drai n bolts .
• B e sur e t o replac e th e wate r pip e drai n bol t
washer s wit h ne w ones .
REAR ENGIN E DRAI N BOL T
3 0 N- m (3. 0 kg-m , 2 2 Ib-ft )
8. Ope n al l fou r bleeders .
1 ) Loose n th e radiato r blee d plug .
2 ) Remov e th e heate r pip e blee d bolt .
3 ) Loose n th e wate r pip e blee d bolt .
4 ) Loose n th e engin e blee d bol t o n th e therm o
cover.
9. Mi x th e recommende d antifreeze/coolan t wit h a n
equa l amoun t o f wate r i n a clea n container .
NOTE:
• Us e onl y Honda-recommende d anti-freeze /
coolant.
• Fo r bes t corrosio n protection , th e coolan t con -
centration s mus t b e maintaine d year-roun d a t
50 % minimum . Coolan t concentration s les s tha n
50 % ma y no t provid e sufficien t protectio n
agains t corrosio n o r freezing .
• Coolan t concentration s greate r tha n 60 % wil l
impai r coolin g efficienc y an d ar e no t recom -
mended.
CAUTION :
• D o no t mi x differen t brand s o f anti -
freeze/coolant .
• D o no t us e additiona l rus t inhibitor s o r anti-rus t
products ; the y ma y no t b e compatibl e wit h th e
recommende d coolant .
Engin e Coolan t Refil l Capacity : Includin g expansio n
tank 2. 1 (2. 2 U S qt , 1. 8 Im p qt )
Manual : 12. 0 (12. 7 U S qt , 10. 6 Im p qt )
Automatic : 12. 0 (12. 7 U S qt , 10. 6 Im p qt )
FRON T ENGIN E DRAI N BOL T30 N- m (3. 0 kg-m , 2 2 Ib-ft )
ProCarManuals.com

Water Pum p
Illustrate d Inde x
NOTE : Us e ne w O-ring s an d ne w specia l bolt s whe n
reassembling .
8 x 1.2 5 mm22 N- m (2. 2 kg- m16 Ib-ft )
ECT SWITC H18 N- m (1. 8 kg-m ,13 Ib-ft ) ENGIN
E COOLAN T
TEMPERATUR E (ECT )GAUG E SENDIN G UNI T9 N- m (0. 9 kg-m ,7 Ib-ft )Apply liqui d gaske tto th e threads .BLEED BOL T10 N- m(1.0 kg-m , 7 Ib-ft )
8 x 1.2 5 mm22 N- m (2. 2 kg-m ,16 Ib-ft )
O-RIN G
Replace .
DRAIN BOLT S
1 0 N- m (1. 0 kg-m , 7 Ib-ft )
Us e rubbe r hose s
when draining .
SPECIAL BOL T
8 x 1.2 5 mm : 2 BOLT S
2 2 N- m (2. 2 kg-m , 1 6 Ib-ft )
Replace . DOWE
L PI N
O-RIN G
Replace .
WATER PUM PInspection , pag e 10-1 1 DOWE LPIN
SPECIA L BOL T
6 x 1. 0 mm : 7 BOLT S
1 2 N- m (1. 2 kg-m , 9 Ib-ft )
Replace .
WATER PASSAG E
O-RING S
Replace .
CONNECTIN
G PIP E
ProCarManuals.com

Accumulator/Pressure Switch

Index/Torque
CAUTION: Do not spill brake fluid on the car; it may damage the
paint; if brake fluid does contact the paint, wash it
off immediately with water.
To prevent spills, cover the hose jpints with rags or shop towels.
Clean all parts in brake fluid and air dry; blow out all passages with compressed air.
Before reassembling, check that all parts are free of
dust and other foreign particles. Replace parts with new ones whenever specified to

do so.

Before disassembling the accumulator unit, bleed the
high-pressure brake fluid out from the system using
the Bleeder T-wrench (see page 19-62('91-'92)('93-'96)

the Bleeder

*: CORROSION RESISTANT BOLT

Make sure no dirt or other foreign matter is allowed
to contaminate the brake fluid. Do not reuse the drained fluid.
Use only clean DOT 3 or 4 brake fluid.

NOTE: Replace the 0-ring with a new one before

reassembly. The accumulator contains high-pressure
nitrogen gas, do not puncture, expose to flame, or at-
tempt to disassemble the accumulator or it may ex-
plode; severe personal injury may result.

19 N·m
(1.9 kg-m,

14 Ib-ft)

PRESSURE SWITCH

SEALING WASHERS

Replace.

BANJO BOLT

35 N·m (3.5 kg-m, 26 Ib-ft)
6 x 1.0 mm

9 N·m
(0.9 kg-m,7 Ib-ft)
ACCUMULATOR

Disposal, page 19-68
* 6 x 1.0 mm

10 N·m (1.0 kg-m, 7 Ib-ft)

O-RING

Replace.
PRESSURE SWITCH

JOINT
6 x 1.0 mm

10 N·m
(1.0 kg-m,

7 Ib-ft)ProCarManuals.com