cooling ACURA NSX 1991 Service Repair Manual

General Info
Specifications
Maintenance
Engine
Cooling
Fuel and Emissions
’91’92 Models
’93’94 Models
’95’96 Models
*TransaxleSuspension
*Brakes (Including ABS)
*Body
*Heating, Ventilation and
Air Conditioning
*Body Electrical
*Engine Electrical
*SRS
1991-96 NSX Main Menu
As sections w/ * include SRS components,
special precautions are required when servicing.
Steering
’91’94 Models
’95’96 Models
ProCarManuals.com

M/T: Manua l Transmissio n A/T : Automati c Transmissio n
Cooling — Sectio n 1 0
Engin
e Lubricatio n — Sectio n 8
Engin
e Bloc k — Sectio n 7
ProCarManuals.com

5. Install the side engine mount, then tighten the bolts
in the numbered sequence as shown ( - ),

12 x
1.26
mm

73 N·m
(7.3 kg-m,
53 Ib-ft)

Replace.
12 x
1.25
mm

95 N·m
(9.5 kg-m,
69 Ib-ft)

SIDE ENGINE

MOUNT

6. Tighten the transmission mount mounting bolt.

MOUNTING BOLT
12 x
1.25
mm

95 N·m (9.5 kg-m, 69 Ib-ft)
7. Tighten the rear mount mounting bolt.
MOUNTING BOLT

12 x
1.25
mm

77 N·m (7.7 kg-m, 56 Ib-ft)
Replace.

Check that the spring clip on the end of each
driveshaft clicks into place.
CAUTION: Use new spring clips.
Bleed air from the cooling system (see page 10-5).
Bleed air from the brake lines {see section 19).
Check the clutch pedal free play (see section 12).

Adjust the clutch guide assemblies when disas-

sembling clutch (see section 12).

Check that the transmission shifts into gear

smoothly.

Adjust the alternator belt (see section 23).
Adjust the A/C compressor belt (see section 22).
Clean battery posts and cable terminals with
sandpaper, assemble, then apply grease to pre-
vent corrosion.
Inspect for fuel leakage (see section 11). After assembling the fuel line parts, turn on
the ignition switch (do not operate the starter) so that the fuel pump operates for approxi-
mately two seconds and the fuel line pressu-
rizes. Repeat this operation two or three times
and check for fuel leakage at any point in the

fuel line.

Check and adjust wheel alignment (see section 18).

Refill the engine with engine oil (see page 8-4 ('91-'92
Models), ('93-Model),or ('94-'96 Models).

Refill the transmission with oil/fluid (see section

13 or
14).ProCarManuals.com

Cooling
Illustrated Index
Syste m is unde r hig h pressur e whe n th e
engin e i s hot . T o avoi d dange r o f releasin g scaldin g
engin e coolant , remov e th e ca p onl y whe n th e engin e i s
cool .
Tota l Coolin g Syste m Capacity : Includin g expansio n
tank 2. 1 (2. 2 U S qt . 1. 8 Im p qt )
5 M/T : 16. 0 (17. 0 US qt , 14. 1 Imp qt )
4 A/T : 16. 5 (17. 4 US qt , 14. 5 Imp qt )
NOTE :
• Chec k al l coolin g syste m hose s fo r damage ,
leak s o r deterioratio n an d replac e i f necessary .
• Chec k al l hos e clamp s an d retighte n i f
necessary .
• Us e ne w O-ring s whe n reassembling .
Radiator, Wate r Pipe s an d Hoses :
BLEED BOL T10 N- m (1. 0 kg-m ,7 Ib-ft )
WASHE RReplace .
HEATER PIP E
RADIATO R
LOWE R HOS E
RADIATO R
UPPE R HOS E
RADIATO REngine coolan t refillin g an dbleeding , pag e 10- 5Leak test , pag e 10- 8Inspec t soldere d joint s an dseam s fo r leaks .Blow ou t dir t fro m betwee ncore fin s wit h compresse d air .If insects , etc. , ar e cloggin gradiator, was h the m of f wit hlow-pressur e water . BLEE
D PLU G
RESISTO R
RADIATO R DRAI N
PLU G
FRON T LOWE R
WATE R PIP E
FRON T UPPE R
WATE R PIP E FA
N SHROU D
5 x 0. 8 m m4.5 N- m (0.4 5 kg-m , 3. 3 Ib-ft )
Replace .
BLEED BOL T
10 N- m (1. 0 kg-m ,7 Ib-ft )
WASHER S
Replace .
WATER PIP E
DRAI N BOLT S
15 N- m (1. 5 kg-m , 1 1 Ib-ft )
WATE RPIPE ASSEMBL YWASHE
RReplace .
FAN MOTO R
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Ignition System

Spark Plug Inspection

1. Inspect the electrodes and ceramic insulator for:

Worn or deformed

electrodes

Damaged

gasket
• Improper gap

• Oil-fouling

• Carbon deposits

• Cracked center

electrode insulator

Cracked

insulator

Burned or worn electrodes may be caused by:

• Advanced ignition timing

• Loose spark plug

• Plug heat range too low

• Insufficient cooling

Fouled plug may be caused by:

Retarded ignition timing

Oil in combustion chamber

Incorrect spark plug gap

Plug heat range too high

Excessive idling/low speed running

Clogged air cleaner element

Deteriorated ignition coil
2. Replace the plug if it is fouled or worn.

NOTE: Do not use spark plugs other than those

listed below.

Spark Plug:

PFR6N-11 (NGK)

PK20PR-L11 (Nippondenso)

3. Make sure that the 1.3 mm (0.051 in) plug gauge

does not go into the gap for the platinum tip plug. If

the gauge goes into the gap, do not attempt to ad-

just the side electrode; replace the plug with a new

one.

Electrode Gap:

Platinum tip plug:

Check and confirm that the

1.3 mm (0.051 in) plug

gauge does not go into the

gap.

Anti-seize compound

applied to threads

4. Screw the plugs into the cylinder head finger-tight,

then torque them to 18 N-m (1.8 kg-m, 13 Ib-ft).

NOTE: Apply a small quantity of anti-seize com-

pound to the plug threads before installing each

plug.ProCarManuals.com

Radiator and Condenser Fan Controls

Description

Fan control system:

The cooling fan system is comprised of the radiator fan, condenser fan (left and right), engine compartment fan, radiator

fan low relay, radiator fan high relay, condenser fan relay, engine compartment fan relay, radiator fan resistor, radiator

fan control sensor, A/C pressure switch, fan control unit, climate control unit, and ECM.

The fan control unit controls the operation of the radiator fan and condenser fans.

It uses inputs from the radiator fan control sensor and the A/C pressure switches (A and B) in the A/C system to deter-

mine when the fans should run and at what speed.

Additionally, the temperature switch shuts down the A/C system if the engine coolant temperature (ECT) exceeds

266°F (130°C). If the pressure in the A/C system is higher than normal, pressure switch A closes and the fans will run at

high speed only. See the A/C section for the description and specifications of that function.ProCarManuals.com

This engine has the following new features.

Type

Displacement
Bore x Stroke
Compression Ratio
Cam, Valve Mechanism
Valve Train
Fuel Supply System Water-cooled V6—90° Cross Flow
2,977 cm3(181.6cu-in)

90 x 78 mm
(3.54
x
3.07
in)
10.2
Dual Overhead Camshafts, VTEC Belt Driven
Sequential Multiport Fuel Injection (SFI)VTEC; High output and a broad power band is achieved through control of low-speed and high-speed valve operation
by the Engine Control Module (ECM).
(Two knock sensors are used to detect octane level of the fuel.)
Titanium connecting rods ; Accomodate high rotation speed and high output. Titanium material of light weight and
high strength is used for the connecting rods.
(Strength is at the same level as iron.)
(Weight is about 30% lighter than iron.)
New mechanism to the intake system; Increased low and middle speed torque and higher output can be achieved by
switching the chamber volume of the intake manifold according to engine speed. This is electronically-controlled.
Cooling system for the mid-ship engine:
Radiator located in front compartment (An aluminum alloy radiator and pipes made of aluminum alloy)
Engine room cooling fan
Expansion tank
The cylinder block is highly rigid with deep water jackets. In order to achieve lighter weight, magnesium is used for the following parts: Cylinder head coverIntake manifold cover
Intake manifold chamber
Major SpecificationsProCarManuals.com

Cooling

Cooling System

Two cooling systems are employed:

An antifreeze/water system with the radiator mounted in the front of the vehicle.

An air-cooling system driven by a fan mounted in the engine compartment.

BLEEDER

RADIATOR

BLEEDER

WATER VALVE

HEATER CORE
DRAIN

DRAINS

BLEEDER

ENGINE DRAIN

WATER PUMP

ENGINE OIL

COOLER

ENGINE DRAIN

FAST IDLE THERMO VALVE

IDLE AIR CONTROL (IAC) VALVE

BREATHER PIPE

THROTTLE

BODY
THERMOSTAT
TEMPERATURE SWITCH
ENGINE COOLANT
BLEEDER
EXPANSION

TANKProCarManuals.com

Engine Removal/Installation

(cont'd)

Torque the engine mounting bolts in sequenceshown below.
CAUTION: Failure to tighten the bolts in the proper

sequence can cause excessive noise and vibration

and reduce bushing life; check that the bushings

are not twisted or offset.
Bleed air from the cooling system (see section 10)
Bleed air from the brake lines (see section 19)
Adjust the throttle cable tension.
Check the clutch pedal free play.
Adjust the clutch guide assemblies when
disassembling clutch (see section 12). Check that the transmission shifts into gear
smoothly (M/T see section 13, A/T see section 14).
Adjust the alternator belt (see section 23).
Adjust the A/C belt (see section 22).
Clean battery posts and cable terminals with sand-
paper, assemble, then apply grease to prevent

corrosion.

Inspect for fuel leakage:
• After assembling fuel line parts, turn on the igni- tion switch (do not operate the starter) so that
the fuel pump operates for approximately two seconds and the fuel line pressurizes. Repeat
this operation two or three times and check whether any fuel leakage has occurred at any
point in the fuel line.
Check and adjust wheel alignment.

10 x
1.25
mm

60 N .
m (6.0 kg-m, 43 Ib-ft)
MOUNTING BOLT SPECIAL BOLT

12 x
1.25
mm

77 N .
m
(7.7 kg-m,
56 Ib-ft)

Replace.
10 x
1.25
mm

60 N .
m
(6.0 kg-m
43 Ib-ft) 73 N.m (7.3 kg-m, 53 Ib-ft)

12 x
1.25
mm

95 N .
m
(9.5 kg-m,
69 Ib-ft)

RUBBER CAP

(M/T only)
SIDE MOUNT
: CORROSION RESISTANT
BOLT/NUT

12 x
1.25
mm

105 N .
m (10.5 kg-m, 76 Ib-ft)

10 x
1.25
mm

60 N .
m (6.0 kg-m, 43 Ib-ft) MOUNTING BOLT FRONT MOUNT
TRANSMISSION
MOUNT (A/T)

12 x
1.25
mm

95 N .
m
(9.5 kg-m,
69 Ib-ft)
SEAT STOPPER
TRANSMISSION
MOUNT (A/T)

REAR MOUNT
SPECIAL NUT
12 x
1.25
mm

77 N .
m
(7.7 kg-m,
56 Ib-ft)

Replace.
M/T:

A/T:

After the engine is in place:ProCarManuals.com

Cylinder Heads

Removal

Engine removal is not required in this procedure.
CAUTION: To avoid damaging the cylinder heads, wait until the engine coolant temperature drops below 100°F (38°C) before loosening the retaining bolts.

NOTE:
Inspect the timing belt before removing the cylinder
heads.
Turn the crankshaft so that the No. 1 piston is at top
dead center (TDC (page 6-25, 26). Mark all emission hoses before disconnecting them.
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.
4. Remove the right rear wheel/tire.
5. Remove the engine under guard, then remove the front exhaust pipe.
6. Remove the rear exhaust pipe.
CAUTION: Do not use an air wrench or hammer to
remove or install the exhaust system unless you
first remove the heated oxygen sensors.

GASKETS

Replace.

FRONT EXHAUST

PIPE

SELF-LOCKING NUTS

10 x
1.25
mm

34N .
m (3.4 kg-m, 25 Ib-ft)

Replace.
REAR EXHAUST

PIPE

SELF-LOCKING NUTS

10 x
1.25
mm

34N .
m (3.4 kg-m, 25 Ib-ft)

Replace.

GASKETS
Replace.

7. Remove the under cover, then remove the water pipe drain bolts and drain the engine coolant.
8. Attach the hoses to front and rear engine drain bolts, then loosen the bolts and drain the engine
coolant.
Bleed air from the cooling system when install-
ing the cylinder heads (page 10-5).
9. Remove the engine oil cooler base assembly (page
6-23).

10. Lower the car.
11. Remove the strut bar (page 5-19).
12. Remove the intake manifold plate and top cover (page 5-21).
13. Remove the throttle cable by loosening the locknut, then slip the cable and nut off the throttle bracketand throttle link (page 5-21).

NOTE:
Take care not to bend the cable when removingit. Always replace a kinked cable with new one.Adjust throttle cable when installing (see sec-

tion 11).ProCarManuals.com