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3-Year / Unlimited-Mile Parts & Labor Nationwide Warranty— up to 5-Year / Unlimited-Mile No-Fault available
12 months of coverage
1-Year
No-Fault Warranty
$99.00
- One-time free replacement, no matter the cause of failure.
- Unlimited miles during the 1-year term.
- $50/hr labor coverage using Mitchell or AllData book time.
4.0L Inline-Six · Trusted since 1961
Remanufactured 4.0L Jeep Engines
Built for long-term reliability. Premium replacement 4.0L inline-six engines for the Jeep Wrangler, Cherokee, Grand Cherokee, Comanche and related AMC/Jeep applications. The legendary 4.0L is known for durability and low-end torque, but high mileage, overheating, oiling concerns, cylinder head cracking and internal wear eventually lead to major failure.
- Zero-Mileage Remanufactured Build
- Crack-Inspected Cylinder Head
- New Rear Main Seal
- 4.7L Stroker Option
- Up to 5-Yr / Unlimited Warranty
Quick Answer: Where to Buy a Remanufactured 4.0L Jeep Engine
Fraser Engines, trusted since 1961, sells zero-mile remanufactured 4.0L Jeep inline-six engines for the 1987–2001 Cherokee XJ, 1987–1992 Comanche MJ, 1991–1995 Wrangler YJ, 1997–2006 Wrangler TJ, 1993–1998 Grand Cherokee ZJ and 1999–2004 Grand Cherokee WJ, plus a 4.7L stroker build for more low-end torque. Every engine gets a crack-inspected, pressure-tested, resurfaced head and new pistons, rings, bearings, timing components, oil pump, gaskets and seals, including the rear main.
Choose Standard (3-year / unlimited-mile warranty), Fraser Advantage™ with all TSB updates and an updated head (5-year / unlimited-mile warranty plus 1 year free No-Fault), or the 4.7L Stroker with the same Fraser Advantage™ coverage. Fraser matches fitment by VIN and head casting. Call 800-731-3177 (press 1 for sales).
Choose Your 4.0L Jeep Engine Option
Option 1
Standard Remanufactured 4.0L
Fully remanufactured 4.0L with new wear components.
- Crack-inspected, pressure-tested head
- New pistons, rings, bearings
- New timing, oil pump and rear main seal
3 Yrs / Unlimited Miles
Option 2 · Fraser Advantage™
Advantage 4.0L
Everything in Option 1, plus:
- Every applicable OEM and aftermarket TSB update
- Updated cylinder head
- 1 year of free No-Fault coverage
5 Yrs / Unlimited + 1 Yr No-Fault
Option 3 · Fraser Advantage™
4.7L Stroker
Fraser Advantage™ build with more displacement:
- Longer-stroke rotating assembly
- 4.7L pistons
- Noticeably more low-end torque on the trail
5 Yrs / Unlimited + 1 Yr No-Fault
Fraser handles warranty claims directly with engine specialists, not call-center reps. Labor is reimbursed using Mitchell or ALLDATA book time. Optional No-Fault upgrades from 1 to 5 years are available on every option. Coverage, eligibility, exclusions and claim procedures are governed by Fraser Engines' written warranty agreement.
4.0L Jeep fitment matters
Vehicle Applications and VIN / Casting-Based Fitment
Jeep 4.0L fitment varies by VIN, model year, cylinder head design, block casting, crankshaft position sensor setup, emissions package, accessory configuration, transmission pairing and platform. Fraser recommends VIN verification before purchase to make sure the correct replacement engine is quoted for your Jeep.
Jeep Wrangler YJ / TJ
Jeep Cherokee XJ
Jeep Grand Cherokee ZJ / WJ
Jeep Comanche MJ
Automatic & Manual
| Make | Model | Years | Engine | Notes |
|---|---|---|---|---|
| Jeep | Wrangler YJ | 1991–1995 | 4.0L Inline-6 | Confirm head casting and sensor setup by VIN |
| Jeep | Wrangler TJ | 1997–2006 | 4.0L Inline-6 | Confirm head casting and sensor setup by VIN |
| Jeep | Cherokee XJ | 1987–2001 | 4.0L Inline-6 | Confirm model year and emissions package by VIN |
| Jeep | Grand Cherokee ZJ | 1993–1998 | 4.0L Inline-6 | Confirm block casting and accessories by VIN |
| Jeep | Grand Cherokee WJ | 1999–2004 | 4.0L Inline-6 | Confirm block casting and accessories by VIN |
| Jeep | Comanche MJ | 1987–1992 | 4.0L Inline-6 | Pickup sharing the XJ drivetrain |
| Jeep | Wagoneer XJ | 1987–1990 | 4.0L Inline-6 | Confirm by VIN |
| AMC / Jeep | Other inline-six applications | Varies | 4.0L Inline-6 | Contact us with your VIN for matching |
VIN- and casting-specific matching: have your full 17-character VIN ready so our team can match the exact 4.0L (or 4.7L stroker) replacement engine for your Jeep. 1987–1990 "Renix" engines and 1991-and-newer "High Output" engines use different sensors and fuel systems.
4.0L Jeep Inline-Six Specifications
| Specification | 4.0L Inline-6 | Fraser 4.7L Stroker |
|---|---|---|
| Displacement | 4.0L / 3,964 cc / 242 cu in | About 4.7L |
| Configuration | Inline 6, overhead valve, 12 valves | Inline 6, overhead valve, 12 valves |
| Bore × stroke | 3.875 in × 3.414 in | Longer stroke |
| Block / head | Cast iron | Cast iron |
| Timing drive | Timing chain | Timing chain |
| Firing order | 1-5-3-6-2-4 | 1-5-3-6-2-4 |
| Factory output | About 173–190 hp, 220–235 lb-ft by year | More low-end torque than stock |
| Production years | 1987–2006 | Fraser Advantage™ build |
The 4.0L Cracked Cylinder Head Problem
Why some 4.0L heads crack
Certain later-production 4.0L head castings, most often identified by the casting number 0331 on roughly 2000–2003 engines, are known to crack between cylinders. The crack lets coolant escape, which leads to unexplained coolant loss, overheating, white smoke or coolant in the oil. Many owners chase the problem with radiators and head gaskets before finding the real cause.
A used 4.0L can carry the same cracked or crack-prone head. Every Fraser 4.0L head is crack inspected, pressure tested and resurfaced, and Fraser Advantage™ builds use an updated head.
Know the warning signs
Common 4.0L Jeep Engine Problems
The 4.0L powered many of Jeep's most recognized vehicles and is respected for long service life, but age, mileage, overheating, cooling-system neglect, oil-pressure concerns, cylinder head cracking and internal wear can make replacement the most practical repair.
Cylinder head cracking
Certain 4.0L head castings are known to crack, allowing coolant loss, overheating or coolant contamination.
Overheating damage
Radiator restrictions, thermostat failure, water pump wear, fan problems or neglect damage the head, gasket and cylinder bores.
Rear main seal and gasket leaks
Oil leakage from the rear main, valve cover, oil pan and timing cover is common on aging 4.0Ls.
Oil pressure and bearing wear
High mileage, sludge, worn bearings or oil pump wear cause low pressure, knocking and bottom-end damage.
Piston skirt and cylinder wear
Internal wear produces cold-start noise, blow-by, oil consumption, low compression or misfires.
Timing set and valvetrain wear
Chain stretch, lifter wear, worn cam components or poor lubrication cause rattling, ticking and performance concerns.
Diagnose first
Repair or Replace? Signs You Need a 4.0L Jeep Engine
Some 4.0L issues can be repaired externally, but severe overheating, internal noise, low compression, a cracked cylinder head, excessive oil consumption or oil-pressure failure make a replacement engine the better long-term repair.
- Knocking, ticking, rattling or internal noise
- Overheating damage or repeated coolant loss
- Low compression or failed leak-down test
- Misfires that continue after ignition and fuel repairs
- Timing chain rattle, ticking or cam/crank codes
- Oil pressure warnings or metal in the oil
- Coolant contamination or suspected cracked head
- Replacement recommended by a licensed repair shop
True remanufacturing, not a budget rebuild
How Your Fraser 4.0L Is Built
Every Fraser 4.0L is torn down to the bare block and rebuilt in a controlled, multi-step process. Fraser Advantage™ builds add every OEM and aftermarket TSB update, and the 4.7L Stroker option adds a longer-stroke rotating assembly for noticeably more low-end torque on the trail.
- Complete teardown to the bare block and industrial cleaning.
- Precision-machined block built to OEM or tighter tolerances.
- Remanufactured cylinder head: crack inspected, pressure tested, resurfaced.
- New pistons, rings and bearings to factory-clearance specs (4.7L pistons on the Stroker).
- New timing components to improve durability.
- New oil pump for proper lubrication and oil pressure.
- New gaskets and seals throughout, including the rear main, to prevent leaks.
- Balanced and tested rotating assembly and final quality inspection.
Used 4.0L engines
Decades-old donors with unknown overheating history and cracked-head risk.
Cheap rebuilds
Reuse marginal parts and skip the updates. The same failure comes back.
Fraser remanufactured
Fully remanufactured, VIN-verified fitment, and up to a 5-year warranty with free No-Fault on Fraser Advantage™.
The Fraser Advantage™
A Better Alternative to Another Used 4.0L Engine
A used 4.0L is risky. Most donors are now older, high-mileage units with unknown cooling-system history, oil leaks, cylinder head concerns or internal wear. Fraser remanufactured 4.0L engines are a professionally renewed direct-replacement alternative with updated components and fitment support, so you repair your Jeep correctly the first time.
- Zero-mileage build, not a questionable salvage engine
- Updated internal components for long-term reliability
- Professionally remanufactured block and cylinder head
- Direct-replacement fitment for Jeep and AMC 4.0L
- Powertrain specialists: engines and transmissions every day
- VIN-based quotes to identify the correct 4.0L
- Shipping to commercial repair shops for easy unloading
- Core return assistance with pickup after install
Know the difference
Used 4.0L vs. Low-Cost Rebuild vs. Fraser Remanufactured
A used 4.0L may come from a decades-old donor with unknown mileage, previous overheating, poor maintenance, oiling damage, cylinder head cracking or excessive internal wear. Even if it runs today, hidden problems may already be developing. Instead of gambling, you receive a professionally renewed replacement backed by Fraser's support.
| Feature | Used Salvage Engine | Low-Cost Rebuild | Fraser Remanufactured |
|---|---|---|---|
| Internal mileage | Prior service mileage; unknown | Varies | Zero miles since remanufacture |
| Factory updates (TSBs) | None | Rarely | All applicable OEM and aftermarket updates applied |
| Cylinder head condition | Unknown; cracking risk | Often reused | Remanufactured head, pressure tested; updated on Fraser Advantage™ |
| Internal components | Existing wear | Reuses marginal parts | New pistons, rings, bearings, timing, oil pump, gaskets and seals |
| Machine work | None | Minimal | Precision-machined block; head pressure-tested and resurfaced |
| Fitment verification | Varies | Varies | VIN-based verification before shipment |
| Warranty | Varies / none | Short-term | 3-Yr (Standard) or 5-Yr + 1-Yr No-Fault (Fraser Advantage™) |
| Core return | Varies | Varies | Free commercial pickup with Fraser support |
4.0L Installation Tips to Protect Your Warranty
- Flush or replace the radiator
- Replace the water pump, thermostat and hoses
- Check the fan clutch and shroud
- Replace the radiator cap
- Prime the oil system before first start
- Install a new crankshaft position sensor
- Watch the temperature gauge during break-in
- Change oil after the first 500 miles
Your engine ships with Fraser's installation guidelines. Follow them closely and keep your receipts to keep your warranty in force.
How to Order Your 4.0L Jeep Engine
- Send your VIN. Use the Fast Quote form, call 800-731-3177 (press 1), or text (586) 284-4941.
- Pick your option. A product specialist confirms fitment and helps you choose Standard, Advantage or 4.7L Stroker.
- Ship to your shop. In-stock engines ship the same day when ordered before 3 PM EST.
- Install and return the core. Fraser coordinates free commercial core pickup after installation.
Answers before you order
4.0L Jeep Engine Replacement FAQs
Is a remanufactured 4.0L Jeep engine better than a used engine?
Yes. Most used 4.0L engines are decades-old with unknown cooling history, oil leaks and cracked-head risk. A Fraser remanufactured 4.0L is zero-mile with a crack-inspected head, all-new internal and timing parts, a new rear main seal, and up to a 5-year / unlimited-mile warranty with free No-Fault on Fraser Advantage™.
What are common 4.0L Jeep engine problems?
Cylinder head cracking on certain castings, overheating damage, rear main seal and gasket leaks, low oil pressure and bearing wear, piston skirt wear, and timing set and valvetrain wear.
Which Jeep 4.0L heads crack?
Most often the 0331 casting found on roughly 2000–2003 engines, which can crack between cylinders. Every Fraser head is crack inspected and pressure tested, and Fraser Advantage™ builds use an updated head.
What is the 4.0L / 4.7L Stroker option?
A Fraser Advantage™ build with a longer-stroke rotating assembly and 4.7L pistons, raising displacement to about 4.7 liters for noticeably more low-end torque on the trail, with larger tires or when towing. It fits like a 4.0L and carries the 5-year / unlimited-mile warranty plus 1 year free No-Fault.
Does Fraser help verify 4.0L Jeep engine fitment?
Yes. Fitment varies by VIN, year, head design, block casting, crank sensor setup, emissions, accessories, transmission and platform, so we confirm it before purchase.
Can Fraser ship my 4.0L Jeep engine to my repair shop?
Yes. We ship directly to commercial repair facilities, free in the continental U.S., and coordinate free commercial core pickup after installation.
Is a No-Fault warranty upgrade available?
Yes. Optional No-Fault upgrades from 1 to 5 years are available on every option, and Fraser Advantage™ options already include 1 year of free No-Fault coverage.
Get Your 4.0L Jeep Engine Today
Talk to a product specialist Mon–Fri 8 AM–5 PM EST, or request a quote online 24/7.
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