The 1991 Ford Ranger is a simple, body-on-frame compact truck that's mechanically straightforward but shows its age in transmission durability and head gasket longevity, especially on the 2.9L V6. These trucks rust aggressively in salt states and suffer from typical '90s Ford electrical gremlins.
2.9L V6 Head Gasket Failure
Common · high severityTypical onset: 80,000-140,000 mi
Symptoms: White smoke from exhaust on cold start, Coolant loss with no visible leaks, Milky oil on dipstick or cap, Overheating under load
Fix: Both head gaskets typically fail together due to cooling system design flaws. Requires cylinder head removal, resurfacing, new gaskets, timing components, and coolant system flush. Budget 12-16 labor hours. Always check for cracked heads while apart—common on high-mileage examples.
Estimated cost: $1,800-2,800
A4LD Automatic Transmission Failure
Common · high severityTypical onset: 100,000-150,000 mi
Symptoms: Slipping between 2nd and 3rd gear, Harsh or delayed engagement, No overdrive or stuck in overdrive, Burnt fluid smell
Fix: The A4LD 4-speed auto is notoriously fragile with weak clutch packs and valve body issues. Rebuild requires 8-12 hours, but many opt for used/reman units due to internal wear patterns. External oil cooler lines rot out and cause fluid loss—inspect carefully during any transmission work.
Estimated cost: $1,400-2,400
Frame and Cab Corner Rust
Common · high severitySymptoms: Visible rust perforation behind rear wheels, Leaf spring mounts separating from frame, Rocker panels crumbling, Frame rail scaling near rear axle mounts
Fix: Rangers in salt states develop catastrophic frame rust, especially in the rear half where salt and mud accumulate. Cab corners rust from inside out. Frame repairs require welding/plating (6-12 hours) but often structural damage is too far gone. Cab corners are 3-4 hours per side with aftermarket panels.
Estimated cost: $800-3,500
Timing Cover and Oil Pan Gasket Leaks
Common · medium severityTypical onset: 90,000-150,000 mi
Symptoms: Oil pooling under front of engine, Oil drips on starter and exhaust, Visible seepage at timing cover seam, Low oil level between changes
Fix: All three engines leak from timing covers and oil pans as gaskets age. Timing cover requires accessory removal and careful RTV application—4-6 hours. Oil pan is straightforward (2-3 hours) but crossmember may need dropping. Often done together since access overlaps.
Estimated cost: $600-1,200
Fuel Pump Failure (In-Tank)
Occasional · high severityTypical onset: 120,000-180,000 mi
Symptoms: No-start with crank but no fire, Stalling when fuel tank below 1/4, Whining noise from tank area, Loss of power under acceleration
Fix: Electric fuel pump sits in-tank and fails from age and sediment. Requires tank drop (2-3 hours). Always replace fuel filter and sock screen at same time. Pumps are affordable but labor adds up. Running tank low repeatedly accelerates pump death.
Estimated cost: $400-700
Rear Wheel Cylinder and Brake Line Corrosion
Common · medium severitySymptoms: Brake fluid leak at rear wheels, Soft brake pedal, Parking brake ineffective, Rear brakes locking prematurely
Fix: Rear drum brake wheel cylinders seize and leak, especially if truck sits. Steel brake lines rust through at frame clips and rear axle. Wheel cylinders are 1-2 hours per side. Brake line replacement (all four corners) is 4-6 hours and highly recommended on Northern trucks over 20 years old.
Estimated cost: $300-1,000
Distributor Cap, Rotor, and Ignition Module Failure
Occasional · medium severityTypical onset: 80,000-120,000 mi
Symptoms: Hard starting when hot, Random misfires and stumbling, Stalling at idle, No-start after heat soak
Fix: TFI ignition modules fail when hot (mounted on distributor). Cap and rotor crack with age causing misfires. Module replacement is 30 minutes, cap/rotor another 30 minutes. Many techs relocate module to fenderwell for better cooling. Carry a spare module if you're keeping the truck—common roadside failure.
Estimated cost: $150-400
Buy one only if the frame is solid, transmission shifts clean, and you can wrench—these are simple trucks that reward basic maintenance but punish neglect with expensive failures.
AI-assisted summary drawn from NHTSA recall data, our labor-times database, and platform knowledge. Not a substitute for a pre-purchase inspection on a specific vehicle.