XJ Trail Spare Parts Guide

Universal Spares — All Vehicles

These spares apply to every platform. Carry them regardless of what you drive.

• U-joints — 1–2 that fit your driveshaft; carry both sizes if your front differs from the rear
• Driveshaft slip yoke grease — lithium grease
• CV axle boot repair kit — if applicable to your axle setup

• Radiator stop-leak tablets (Bar's Leaks) — buys a recovery, not a fix
• Upper radiator hose — OEM equivalent; write the part number on the bag
• Thermostat + gasket
• 1 gallon premixed 50/50 coolant

• Serpentine belt — exact OEM part number; write it on the bag before you go
• Lower radiator hose — carry both if upper is a known failure on your truck

• Fuse assortment — same range as your tools kit; double it here
• Spare relay — 87/30/85/86 style, the most common automotive relay
• Spare bulbs — headlight (H4 or vehicle fitment), brake light, turn signal

• Engine oil: 2 quarts — correct viscosity; label it
• Power steering fluid: 1 qt
• Brake fluid: 1 small bottle — DOT 3 or DOT 4; label which spec your truck takes
• ATF: 1 qt — if automatic; label the spec
• Gear oil: 1 qt — 75W-90 or 80W-90 for front and rear diff
• Transfer case fluid: 1 qt — same as gear oil for most, ATF for some; label it

• Grade 8 bolt assortment — M8, M10, M12 in common lengths
• SAE bolt assortment — 3/8-16, 7/16-14, 1/2-13
• Nylock nuts to match
• Cotter pins — assorted
• Safety wire — stainless, .032"

XJ-Specific Spares

The XJ has a predictable failure signature built around the 4.0L engine, its electrical system, and the steering components that take abuse on aggressive terrain.

• Upper AND lower radiator hose The XJ runs hot under load. Carry both hoses. The plastic radiator neck fails on aged trucks — carry a spare radiator cap rated to spec. The water pump bolts externally and can start leaking suddenly. If you're doing remote runs, carry one.
• Crankshaft position sensor (CPS) The most trail-common XJ strand. The CPS dies in heat with no warning — the engine just stops and won't restart. Under $20. Part number varies by year; look it up before the trip and write it on the bag. This is the highest-priority spare on the list.
• Schrader valve cap (fuel rail) The Schrader valve on the fuel rail sticks open and causes hard starts after a hot soak. The cap costs $1. Carry two.
• Front CV axle shaft If you're running 33"+ tires and aggressive angles, the inner axle joint is the failure point. Write the part number on the box before you go.
• Outer tie rod end (Moog ES3480) + drag link (Moog DS1266) Tie rod ends fail. Drag links bend on rock hits. Carry one outer tie rod end and a drag link. If you've ever had death wobble, also carry the track bar — OEM or aftermarket, whichever is on the truck. Carry two front upper control arm bolts as well; they back out.
• ASD relay + fuel pump relay (same part number — carry two) Both live in the TIPM box under the hood. Both fail without warning and strand the vehicle. They're the same relay, swappable. Two relays weigh nothing and cost under $15 total.
• Bar's Leaks Copper (tablet/pellet version) The 4.0L head gasket fails between cylinders 3 and 4. The stop-leak tablet doesn't fix it, but it gets you out. Also carry a can of Bar's engine oil treatment if you see milky oil on the dipstick.
• Correct fluids for your drivetrain Automatic: ATF+4 (Chrysler spec). Manual AX-15: Redline MTL or equivalent — not universal gear oil; the AX-15 is picky about this. NSG370 manual: use the specified fluid. NP231 transfer case: ATF+4.