GMC Truck›C-Series Pickup 2WD CNG›1998›Overview/gmc-truck/c-series-pickup-2wd-cng/1998/base/

1998 GMC Truck C-Series Pickup 2WD CNG

Factory specifications, fluid capacities, torque values, EPA fuel economy and the federal safety record for the 1998 C-Series Pickup 2WD CNG.

The 1998 GMC Truck C-Series Pickup 2WD CNG takes 4.5 qt of 5W-30 engine oil.

Quick specs

Fluid capacities, tune-up values and fuel economy at a glance.

Engine oil capacity4.5 qtOEM · verified

Engine oil type5W-30 APIOEM · verified

Lug nut torque140 ft-lbsOEM · verified

Fitment & sizes

Replacement part sizes and factory part numbers — battery, bulbs, filters and belts.

From the factory this vehicle uses a BCI 78 · 600 CCA battery, OE oil filter 19210286. Note the factory fuel filter is now discontinued — plan on a superseded or quality aftermarket equivalent, which the part pages below list where known. Each part links to every other vehicle that shares it, so a part you already stock may fit more of your fleet than you'd expect.

Battery groupBCI 78 · 600 CCAOEM · verified

Tire sizeLT245-75R16EOEM · verified

Wheel / rim6.5-J inOEM · verified

OE service part numbers OEM · verified

Engine oil filter	19210286 alt 25013454
Engine air filter	25168081 alt 25168082
Fuel filter	25171792 discontinued
Spark plug	12681665
Front wiper blades	93441742
Serpentine belt	19244955 alt 19355374
Thermostat	12632948 alt 12551507

Service quick specs OEM factory data

Capacities, torques and tune-up values from the factory service manual.

This engine holds 4.5 qt of 5W-30 API engine oil, 80W-90 · GL-5 in the differential, DOT 3 brake fluid. Torque lug nuts to 140 ft-lbs. The firing order is 1-6-5-4-3-2. Note the cylinder-head bolts finish on a torque angle (torque-to-yield) — they stretch permanently and should be replaced, not reused, during any head service.

Lubricants & capacities

Brake Fluid	DOT 3
Differential Gear Oil	80W-90 · GL-5
Differential Gear Oil Capacity	5.5 qt
Differential Gear Oil	80W-90 · GL-5
Differential Gear Oil Capacity	8.5 qt
Engine Oil	5W-30 · API
Engine Oil Capacity	4.5 qt
Engine Oil	5W-30 · API

Engine torques

Crankshaft Pulley and/or Damper Bolts	74 ft-lbs
Crankshaft Pulley and/or Damper Bolts	110 ft-lbs
Cylinder Head Steps	Apply sealant GM P/N 12346004
Cylinder Head Steps	Apply sealant GM P/N 12346004
Cylinder Head Steps	Apply the thread sealant GM P/N 12346004
Cylinder Head Steps	Apply sealer GM P/N 12346004
Exhaust Manifold to Cylinder Head Bolts	40 ft-lbs
Intake Manifold to Engine Bolts	11.0 ft-lbs

Chassis torques

Leaf Spring to Axle (U-bolts)	110.0-150.0 ft-lbs
Leaf Spring to Chassis Bracket	110.0 ft-lbs
Leaf Spring Rear Shackle to Chassis Bracket	70.0 ft-lbs
Lug Nuts	140 ft-lbs

Ignition

Cylinder Firing Order	1-6-5-4-3-2
Cylinder Firing Order	1-8-4-3-6-5-7-2
Cylinder Firing Order	1-8-7-2-6-5-4-3
Cylinder Firing Order	1-8-4-3-6-5-7-2
Cylinder Firing Order	1-6-5-4-3-2
Spark Plug Manufacturer	AC Delco
Spark Plug Gap	0.060 in
Spark Plug Torque	11-14 ft-lbs

Battery & A/C

Refrigerant	R134a
Refrigerant Capacity	2.00-2.50 lbs
Oil Group	PAG
Oil Type	GM part number 12345923 or equivalent.
Oil Capacity	8.00 oz
Standard BCI Group Number	78
Standard BCI Cranking Performance	600 cca
Standard BCI Group Number	78

Service checks

Pressure Test	20 psi
Radiator Cap Pressure Relief	15 psi
Thermostat Opening Temperature	188-206 °F
Fuel Pump Pressure Minimum	66.0 psi
Key ON Engine OFF (KOEO)	60-66
RPM	50-63 @ Idle rpm
Fuel Pump Pressure Minimum	66.0 psi
Key ON Engine OFF (KOEO)	60-66

Brakes

Torque Caliper to Bracket	15 ft-lbs
Torque to Knuckle	38 ft-lbs
Torque Caliper to Bracket	15 ft-lbs
Torque to Knuckle	38 ft-lbs
Minimum Pad Thickness	Front: 0.030; Rear: 0.030 specification
Drum Runout Limit	0.006 in
Drum Nominal Diameter	10 in / 11.15 in / 13 in
Drum Maximum Machining	10.05 in / 11.21 in / 13.06 in

Multi-step torque procedures OEM · verified

Cylinder Head — tightening sequence 4 stages

1	all bolts	22 ft. lbs
2	long bolts	75 degrees
3	medium bolts	65 degrees
4	55

Cylinder Head — tightening sequence 2 stages

1	all bolts	22 ft. lbs
2	long bolts	75 degrees

Cylinder Head — tightening sequence 2 stages

1	22 ft. lbs.	22 ft. lbs
2	long bolts	75 degrees

Cylinder Head — tightening sequence 4 stages

1	20 ft. lbs.	20 ft. lbs
2	55 ft. lbs.	55 ft. lbs
3	55 ft. lbs.	55 ft. lbs
4	90

Cylinder Head — tightening sequence 2 stages

1	37 ft. lbs.	37 ft. lbs
2	bolts 1, 2, 3, 6, 8, 9, 12, 13, 14, 15, 16	150 degrees

Intake Manifold to Engine Bolts — tightening sequence 1 stages

22 ft. lbs., step 2: 30

22 ft. lbs

Exhaust Manifold to Cylinder Head Bolts — tightening sequence 1 stages

22.0

Exhaust Manifold to Cylinder Head Bolts — tightening sequence 1 stages

22.0

Intake Manifold to Engine Bolts — tightening sequence 1 stages

40.0

Factory maintenance schedule OEM · verified

Normal service, condensed from the factory interval matrix.

Under the factory schedule, replace the engine oil and filter every 7,500 mi.

At 3,000 mi	Drive Axle Assembly (drain & refill)
Every 3,000 mi	King Pin (lubricate)
Every 5,000 mi	Brake Hydraulic System (inspect fluid level) · Steering Linkage (lubricate) · Steering System (inspect)
Every 7,500 mi	CV Joint Boot (inspect) · Differential (inspect fluid level) · Driveshaft Slip Yoke (lubricate) · Driveshaft U-Joint (lubricate) · Engine Oil (drain & refill) · Engine Oil Filter (replace)
Every 10,000 mi	Air Intake System (inspect)
Every 12,000 mi	Underbody Splash Shield (inspect)
Every 15,000 mi	Cabin Air Filter (replace)
Every 30,000 mi	Clutch Cross Shaft (lubricate) · Clutch Release Lever Pivot Points (lubricate) · Fuel Filter (replace) · Wheel Bearing (inspect)
Every 60,000 mi	Accessory Drive Belt (inspect) · Crankcase Depression Regulator Valve (inspect) · EGR System (inspect) · Exhaust Pressure Regulator (inspect) · Fuel Evaporative Emission Control System (inspect) · Fuel Line (inspect)