SERVICE GUILD: NEW 2.3 QUAD 4 ENGINE SPECS.

MODELS AFFECTED: 1988 SKYLARKS

The new Quad 4 will be an optional engine for the 1988 Buick Skylark. "4" means that there are four valves per cylinder. With its chain-driven double overhead camshafts, the Quad 4 is GM's first high production engine of its type ever.

ENGINE DESCRIPTION

- 150 HP @ 5,200 rpm - 1.1 HP per cubic inch - 160 ft. lbs. of torque @ 4,000 rpm - 7,000 rpm red line - 9.5 to 1 compression ratio - Two overhead camshafts - Direct-acting lifters - Cylinder block - cast grey iron - Head, camshaft housing, oil pan, timing chain housing - aluminum

COMPONENT DESCRIPTION

One of the most innovative elements of the Quad 4 is a manufacturing process called "microsizing". This close-tolerance process is used on the cylinder block, cylinder bores, crankshaft bearing bores, connecting rods, crankshaft and piston pin bores. Microsizing produces the necessary finishes and geometry needed to meet the low friction design goals.

CRANKSHAFT

- The crankshaft is cast nodular iron with eight counterweights. - It is a rolled fillet crankshaft for additional strength. - It has a pressed-on oil pump drive gear which is serviced separately. - It has an ignition reluctor wheel with seven notches machined into the number five counterweight. - It has a highly polished microfinish on rod and main bearing journals.

HEAD

- Aluminum head with pressed-in sintered iron valve guides and valve seats.

CAMSHAFT CARRIER HOUSING

- Two piece camshaft carrier which utilizes camshaft bearing journals that are smaller than the camshaft lobes for reduced friction. The cam carrier halves seal together with a silicone bead seated into a groove machined into the carrier.

OIL PUMP

- Gerotor design driven by a steel gear on the crankshaft.

CONNECTING RODS

- Floating piston pins retained by a wire ring on each end. - Connecting rods are forged steel with a bronze bushing for increased piston pin life. An oil cooling hole which indexes once per revolution with the connecting rod oil feed hole is drilled into the rod on the exhaust side.

PISTONS

- Cast aluminum pistons. - .010" oversize pistons are available for service. - Piston pin bore is slightly offset to the exhaust side of the block to reduce skirt load on the power stroke. This results in quieter engine operation and increased durability.

IGNITION SYSTEM

- Under an attractive die case cover is a unique ignition system. The ignition assembly cover also serves as a heat sink for the ignition module, which is mounted on the top of the engine between the two camshaft housings. The ignition module includes closed loop dwell control and limited backup spark timing control. The ignition is a fast-rise, two coil system with the coils bolted to the ignition assembly cover directly above the spark plugs.

The Integrated Direct Ignition (IDI) module fits directly onto the spark plugs, eliminating spark plug wires. Service procedure is to apply release agent to the spark plug porcelain. Spark plug torque is 21-24 N.m cold. Undertorqued spark plugs may lose torque during heat cycles and loosen.

IGNITION SYSTEM

- Multiport Fuel Injection system with Rochester Products injectors. - A cold start injector is not needed.

FUEL DELIVERY

- 300 kpa/43 psi system pressure regulator and an extruded aluminum fuel rail.

QUAD 4 SERVICE INFORMATION

TIMING CHAIN

- The timing chain is a double-row roller chain designed to last for the life of the engine. A hydraulic tensioner and three guides control chain motion. The hydraulic tensioner is fed by engine oil.

A burst of chain noise rattle may occur after overnight or a 1-2 hour hot soak. This is caused by a 1-2 second delay in engine oil pressure buildup to the hydraulic chain tensioner.

OPERATING CHARACTERISTICS ON SHORT DRIVES

- Milky deposits in crankcase.

In cold weather, repeated short trips with limited engine warmup may allow moisture to accumulate in the engine oil. This can cause milky deposits to form on internal engine surfaces, and may be visible on the oil dipstick. Running the engine at full operating temperature dissolves the deposits, and evaporates the moisture, allowing their removal through the engine vent system. There are no effects on engine durability or performance. This condition is not uncommon in other internal combustion engines.

NORMAL MAINTENANCE REPLACEMENT PARTS

Air Filter Element 2.3L L-4 (Engine Code D) AC Type A-1088C

Engine Oil Filter 2.3L L-4 (Engine Code D) AC Type PF-40 or PF-47

Spark Plugs 2.3L L-4 (Engine Code D) AC Type FR3LS Gap 0.035" (.889mm)

CAPACITIES AND SPECIFICATIONS

Liters Quarts

Cooling System 2.3L L-4 (Engine Code D) 7.20 7.60

Engine Crankcase 2.3L L-4 (Engine Code D) 3.78 4.00

Oil Viscosity API Oil Requirements are SF/CC or SF/CD 5W-30

Thermostat Temperature 91 degrees C (195 degrees F)

OIL PRESSURE (5W30 Oil)

Minimum Oil Pressure: 10 psi at 900 rpm 25 psi at 2000 rpm

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.