JeepWrangler19984.0L/jeep/wrangler/1998/4-0l/
TJ platform

1998 Jeep Wrangler — 4.0L

Factory specifications, fluid capacities, torque values, EPA fuel economy and the federal safety record for the 1998 Wrangler 4.0L.

Engine 4.0LTransmission Automatic 3-spd

The 1998 Jeep Wrangler, built on the TJ platform, is equipped with a 4.0L engine and a 3-speed automatic transmission, requiring 6 quarts of oil with a filter change using 10W-30 or 5W-30 viscosity. Its EPA fuel economy ratings stand at 13 mpg city, 16 highway, and 14 combined. Within the model’s complaint history from 1990 to 2023, this year’s 271 owner complaints—primarily in the engine and engine cooling category, along with six recalls—place it well below the 2018 peak of 1,793 but above the 1996 low of just five, marking it as a relatively moderate year for reported issues.

Model year200620052004200320012000199919981997

Quick specs

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

Engine oil capacity6 qt w/ filterOEM · verified
Engine oil type10W-30 / 5W-30 APIOEM · verified
Lug nut torque85-110 ft-lbsOEM · verified
EPA fuel economy13/16/14 mpgEPA · verified

Fitment & sizes

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

From the factory this vehicle uses a BCI 34 · 500 CCA battery, OE oil filter 05281090AB. Note the factory fuel filter and front wiper blades are now discontinued — plan on a superseded or quality aftermarket equivalent, which the part pages below list where known.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 34 · 500 CCAOEM · verified

OE service part numbers OEM · verified

Engine oil filter05281090AB
Engine air filter04797777AC
Fuel filter04798301 discontinued
Spark plug68304020AA
Battery1BPB5800AA
Front wiper blades55154762AF discontinued
Serpentine belt53011035 alt 53010254AB
Thermostat52028186AC alt 53020547AC

Full specifications

Engine, drivetrain, dimensions and economy.

Engine & drivetrain NHTSA vPIC

TransmissionAutomatic 3-spd

Ratings & economy EPA / vPIC

EPA city / highway / combined13 / 16 / 14 mpg
Drivetrain4-Wheel or All-Wheel Drive
Recommended fuelRegular Gasoline

Performance & power Independent road tests

0–60 mph, quarter-mile, horsepower and torque from independent road tests.

No 1998 road test on record; the results below are same-engine tests from nearby model years, each shown under its own year.

7.6–9.8 sec0–60 mph (tested)quickest 7.60 sec — 1997 Sport 2-door
YearTrim / engine0–60¼ mileHPDrivetrain
1997Sport 2-door 4.0L I-67.60 sec16.30 sec181 hp4x4
1997Sport 2-door 4.0L I-69.10 sec16.90 sec181 hp4x4
1999Sport 2-door 4.0L I-69.30 sec17.10 sec181 hp4x4
2003Rubicon 2-door 4.0L I-69.80 sec17.30 sec190 hp4x4

Service quick specs OEM factory data

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

This engine holds 6 qt w/ filter of 10W-30 / 5W-30 API engine oil, 75W-90 · GL-5 · 80W-140 in the differential, DOT 3 brake fluid. Torque lug nuts to 85-110 ft-lbs, the oil drain plug to 25.0 ft-lbs. The firing order is 1-5-3-6-2-4.

Lubricants & capacities

Brake FluidDOT 3
Differential Gear Oil75W-90 · GL-5 · 80W-140
Differential Gear Oil Capacity4.9 Pints,
Engine CoolantHOAT · MS9769
Engine Oil10W-30 · API · 5W-30
Engine Oil Capacity6 qt w/ filter
Power Steering FluidMS-5931

Engine torques

Connecting Rod (Large End) Bearings33-35 ft-lbs
Engine Oil Pan Drain Plug25.0 ft-lbs
Oil Pump to Cylinder BLock Bolts/StudsPump bolts: 14 ft-lbs, Cover bolts: 9 ft-lbs

Chassis torques

Lug Nuts85-110 ft-lbs
Transfer Case Fill Plug35.0 ft-lbs
Transfer Case Drain Plug35.0 ft-lbs
Front Wheel Hub175 ft-lbs

Ignition

Cylinder Firing Order1-3-4-2
Cylinder Firing Order1-5-3-6-2-4
Ignition Coil Primary Resistance.95-1.20 Toyodenso ohms
Ignition Coil Secondary Resistance11,300-13,300 ohms
Spark Plug ManufacturerChampion
Spark Plug Gap0.040 in
Spark Plug Torque22.0 ft-lbs

Battery & A/C

RefrigerantR134a
Refrigerant Capacity1.25 lbs
Oil GroupPAG
Oil TypeSP-20
Oil Capacity8.10 oz
Optional BCI Group Number34
Optional BCI Cranking Performance600 cca
Standard BCI Group Number34

Service checks

Pressure Test18 psi
Radiator Cap Pressure Relief12-18 psi
Thermostat Opening Temperature195 °F
Regulated Fuel System Pressure (With Vacuum)47-51 psi
Engine Compression120-150 PSI. 30 Maximum variation PSI.

Brakes

Torque to Knuckle7-15 ft-lbs
Minimum Pad Thickness0.030 in
Minimum Shoe Thickness0.030
Rotor Max Parallel Variation0.0005 in
Rotor Runout Limit0.005 in
Rotor Nominal Thickness From0.944 in
Rotor Nominal Thickness To0.944 in
Rotor Minimum Machining0.894 in

Multi-step torque procedures OEM · verified

Cylinder Head — tightening sequence 4 stages

Prep Coat threads of left hand front bolt with sealant

122 ft. lbs.22 ft. lbs
245 ft. lbs.45 ft. lbs
3all bolts except L.H. front bolt110 ft. lbs
4100
Main Bearings — tightening sequence 7 stages
1caps 1, 2, 4, 5, 6, and 740 ft. lbs
2caps 1, 2, 4, 5, 6, and 770 ft. lbs
3caps 1, 2, 4, 5, 6, and 780 ft. lbs
4Push the crankshaft forward and backward. Load the crankshaft front or rear and tighten cap bolt No.3 to 40 ft. lbs.40 ft. lbs
5Tighten to 70 ft. lbs.70 ft. lbs
6Tighten to 80 ft. lbs.80 ft. lbs
7Rotate the crankshaft after tightening each main bearing cap to ensure the crankshaft rotates freely.

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; spark plugs every 30,000 mi; coolant every 7,500 mi. The big-interval services (every 7,500 mi for coolant, and the transmission fluid) are the ones owners most often skip — on a lower-mileage example, assume the original fluids are still in it and check them first.

Every 7,500 miBody Fasteners (torque) · Brake Line (inspect) · CV Joint Boot (inspect) · Driveshaft U-Joint (lubricate) · Engine Coolant System (leak inspection) · Engine Oil (drain & refill)
Every 15,000 miBattery (inspect electrolyte level)
Every 22,500 miBrake Linings (inspect)
Every 30,000 miAccessory Drive Belt (inspect) · Drive Axle Assembly (drain & refill) · Engine Air Filter Element (replace) · Engine Coolant System (drain, flush & refill) · Spark Plugs (replace) · Transfer Case Assembly (drain & refill)
Every 37,500 miBands (adjust) · Transmission Assembly (drain & refill) · Transmission Fluid & Filter (replace)
At 51,000 miEngine Coolant System (drain, flush & refill)
Every 60,000 miSpark Plug Wires (replace)

Owner how-tos

Condensed service procedures for routine maintenance. Procedures that require dealer diagnostic equipment are identified and summarized only.

Common procedures

Key fob — remote (RKE) programming programming new fob buttons Dealer tool OEM · verified
Tool requiredDRBIII scan tool (dealer / locksmith)
WhyTransmitter codes are written into the receiver in the passenger door module
Anti-theft (SKIS) — module initialization after immobilizer module replacement Dealer tool OEM · verified
When neededAfter Sentry Key Immobilizer Module (SKIM) replacement
Tool requiredDRBIII scan tool
Also requiredThe vehicle's four-digit PIN code

Reliability & federal safety record

Owner-reported issues, recalls, investigations and service bulletins on record with NHTSA — an unfiltered look at what owners actually experience.

The 1998 Jeep Wrangler recorded 271 complaints, 6 recalls, zero investigations, and 75 technical service bulletins (TSBs), placing it in the declining phase of a sharp complaint spike that began in 1997, which itself saw a dramatic surge to 455 complaints from just 5 in 1996. Compared to the years immediately following, 1998's complaint count of 271 was slightly elevated versus 1999's 223 but remained lower than the 288 logged in 2000, suggesting the 1998 model navigated a transitional period between the initial defect cluster and subsequent fluctuation. The top complaint categories were Engine & Engine Cooling (38), Electrical System (26), Power Train (20), and Air Bags (16), accompanied by 24 crash-related and 9 fire-related complaints, though the data does not specify root causes for these incidents. Recalls held steady at 5–7 annually across 1997–2000, indicating no acute safety crisis unique to 1998, while the 75 TSBs reflect persistent but non-critical technical guidance. The 1998 model thus occupies a middle position in the generation's reliability arc—post-spike normalization rather than peak complaint activity. The takeaway: 1998 represents a reasonable purchase within this generation, benefiting from the resolution trajectory of the 1997 issues, though buyers should prioritize pre-purchase inspection of engine cooling, electrical, and powertrain systems given the documented complaint distribution.

6
Open recalls
NHTSA campaigns
75
Service bulletins
Manufacturer communications
0
ODI investigations
Office of Defects Investigation
271
Owner complaints
24 involved a crash · 9 a fire

Owner complaints filed with NHTSA, by component

All 271 complaints on record, top 8 components.

Engine & Engine Cooling38
Electrical System26
Power Train20
Air Bags16
Structure14
Suspension12
Electrical System,Air Bags11
Seat Belts11

Source: NHTSA Office of Defects Investigation complaint database.

Recalls NHTSA · verified

Showing 2 of 6 campaigns on record for this vehicle.

06E022000Service Brakes, HydraulicReported 13/03/2006

CERTAIN AFTERMARKET BRAKE HYDRAULIC MASTER CYLINDERS SOLD AS REPLACEMENT BRAKE CYLINDERS FOR CERTAIN FORD, DAIMLERCHRYSLER, AND JEEP PASSENGER VEHICLES. THESE BRAKE CYLINDERS WERE SOLD UNDER THE BRAND NAMES OF NAPA… Remedy: AFFINIA (BRAKE PARTS, INC.) WILL REPLACE THE SUBJECT BRAKE HYDRAULIC MASTER CYLINDERS FREE OF CHARGE. THE RECALL BEGAN ON MARCH 20, 2006. OWNERS CAN CONTACT AFFINA GROUP CUSTOMER…

06E026000Exterior LightingReported 23/03/2006

CERTAIN PRO-A MOTORS CORNER LAMPS, TURN SIGNALS, AND HEADLIGHTS SOLD AS REPLACEMENT LAMPS FOR USE ON CERTAIN PASSENGER VEHICLES LISTED ABOVE. SOME COMBINATION LAMPS THAT ARE NOT EQUIPPED WITH AMBER SIDE REFLECTORS FAIL… Remedy: PRO-A MOTORS WILL NOTIFY OWNERS AND OFFER TO REPURCHASE THE LAMPS. THE RECALL BEGAN ON APRIL 3, 2006. OWNERS MAY CONTACT PRO-A MOTORS AT 323-838-2988.

Technical service bulletins NHTSA · verified

Showing 5 of 75 bulletins on record with NHTSA.

BulletinDateComponentSummary
90042752020-07-22Electrical SystemKEY, Master If replacing the key/FOBIK on a WJ, KJ, TJ, or PT Cruiser, use the "AC" NIC…
90042752020-07-22Electrical SystemKEY, Master If replacing the key/FOBIK on a WJ, KJ, TJ, or PT Cruiser, use the "AC" NIC…
08-049-202020-04-22Electrical SystemCharging System, Battery Diagnostic Tools and Warranty This information only bulletin…
D-20-02 Rev. A2020-03-04EquipmentDIPAP Requirements - Addition of Jeep Wrangler (JL/JK) and Jeep Gladiator (JT) Hard Top…
31005192019-11-20StructureUse of Aftermarket Parts This bulletin involves discussing FCA US LLC position with…

Common OBD-II trouble codes

The most common OBD-II codes for this vehicle's emissions system. These are standardized SAE J2012 definitions, not vehicle-specific fault reports.

P0420
Catalyst system efficiency below threshold — Bank 1
P0300
Random / multiple cylinder misfire detected
P0171
System too lean — Bank 1
P0455
Evaporative emission system leak detected — large leak
P0128
Coolant thermostat below regulating temperature
P0442
Evaporative emission system leak detected — small leak

VIN tools

Decode factory build data for a specific vehicle by VIN.

VIN
Decode a VIN to confirm the transmission and build data for a specific Wrangler. OEM
Build data
Plant, GVWR class, engine and body data for any 17-character VIN.
Recalls
Check open recall campaigns against a specific vehicle by VIN.

Vehicles with shared specs

Find every vehicle that shares this one's battery, bulbs, oil capacity, platform or parts.

Reference guides

Cross-vehicle references for the kinds of data on this page.

Frequently asked

How much oil does the 1998 Wrangler 4.0L take?

6 qt w/ filter of ABOVE 0 degrees F: 10W-30 API, BELOW 60 degrees F: 5W-30 API, per the factory manual.

Does the 1998 Wrangler have open recalls?

NHTSA lists 6 recall campaign(s) for this model year. Check your specific vehicle by VIN.

What gas mileage does the 4.0L get?

EPA figures are 13 city / 16 highway / 14 combined mpg.