The 1970 AMC Rebel Machine is a limited-production muscle car with the 390ci V8 and automatic transmission. While the drivetrain is generally robust, age-related issues dominate—expect transmission mounts, cooler lines, and bottom-end bearing wear if the engine has seen hard use or poor maintenance.
Transmission Mount Failure
Common · medium severityTypical onset: 50,000-80,000 mi or after 50+ years of age
Symptoms: Clunking when shifting into drive or reverse, Excessive drivetrain movement during acceleration, Vibration at idle in gear
Fix: Replace transmission mount and crossmember bushings. Typically 1.5-2 hours labor. On these older AMCs, the rubber deteriorates even with low miles due to age.
Estimated cost: $150-300
Transmission Oil Cooler Line Corrosion and Leaks
Common · high severitySymptoms: Transmission fluid pooling under vehicle, Low fluid level causing delayed engagement, Burnt fluid smell if driven low on fluid
Fix: Replace steel cooler lines (often rusted through at fittings or along body contact points). 2-3 hours labor including fluid refill. Neglect leads to transmission starvation and catastrophic failure.
Estimated cost: $250-500
390ci Bottom-End Bearing Wear
Occasional · high severityTypical onset: 80,000-120,000 mi or high-rpm abuse
Symptoms: Knocking or rumbling noise at idle, worse when warm, Low oil pressure at idle, Metallic debris in oil pan
Fix: Main and rod bearings replacement requires full engine disassembly—crankshaft removal, bearing installation, plastigage clearances. 16-24 hours labor for in-chassis rebuild, more if block needs machine work. These engines tolerate abuse but eventually the forged crank wears the soft babbitt bearings.
Estimated cost: $2,500-4,500
Piston Ring Blowby and Cylinder Wear
Occasional · medium severityTypical onset: 100,000+ mi or stuck rings from sitting
Symptoms: Excessive crankcase blowby through breather, Blue smoke on acceleration, Loss of compression, High oil consumption
Fix: Ring replacement requires bore inspection—often needs 0.030" overbore and new pistons if taper exceeds spec. 20-30 hours for complete teardown, machine work, reassembly. Many Machines sat for decades and developed stuck rings.
Estimated cost: $3,500-6,000
BorgWarner Automatic Transmission Failure
Occasional · high severityTypical onset: 60,000-100,000 mi or abuse
Symptoms: Slipping in 2nd or 3rd gear under load, Delayed engagement when cold, No reverse or erratic shifting, Burnt fluid
Fix: Rebuild requires clutch pack replacement, band adjustment, valve body servicing. 8-12 hours labor for R&R and rebuild. These BW automatics are less common than TorqueFlites—parts availability is tighter and specialists fewer.
Estimated cost: $1,800-3,200
Fuel System Varnish and Filter Clogging
Common · medium severitySymptoms: Hard starting after sitting, Stumbling or hesitation under acceleration, Stalling at idle
Fix: Replace inline fuel filter, clean or replace carburetor, flush tank if varnish is severe. 2-4 hours depending on carb condition. Machines that sat for years develop varnish in the Holley or Carter carb—expect to rebuild or replace.
Estimated cost: $300-800
Buy one if you're handy or have a trusted AMC specialist—parts are available but not at every corner, and the transmission is less supported than a TorqueFlite; expect deferred maintenance on any survivor.
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.