1975 PLYMOUTH TRAIL DUSTER

Typical onset: 80,000-120,000 mi

Symptoms: Hard starting when warm, especially after sitting 15-30 minutes, Rattling noise from front of engine on cold start for 2-3 seconds, Backfiring through carburetor, poor idle quality, Check timing and find it's retarded 8-12° even after adjustment

Fix: Replace timing chain, gears, and tensioner as a set. On V8s expect 4-5 hours labor; Slant Six runs 5-6 hours due to awkward access. Must remove harmonic balancer, timing cover, water pump. Critical: align timing marks precisely or you'll have valve-to-piston contact on 360/400 engines. Use double-roller chain set for longevity.

Estimated cost: $450-750

Symptoms: Raw fuel smell, black smoke on acceleration, 8-10 mpg when should be 12-14, Hesitation or stumble off idle, surging at steady cruise 45-55 mph, Hard starting when hot, flooded condition, fuel dripping from air cleaner base, Idle speed increases 200-300 rpm after warmup then slowly drops

Fix: Ethanol fuel destroys original cork and rubber components in these carbs. Full rebuild with modern ethanol-compatible kit: 2-3 hours for experienced tech, 4-6 for first-timer. Carter BBD (Slant Six and 318) is simpler; Thermoquad (360/400) has plastic main body prone to warping—often better to swap to an Edelbrock 1406 for $350 and be done. Set float levels precisely with transparent gauge.

Estimated cost: $280-650

Symptoms: Visible rust perforation under driver/passenger feet, carpet wet after rain, Soft or spongy floor when stepping in, seat mount bolts loose or spinning, Cab corners rusted behind rear doors, rocker panels crumbling, Body mounts rotted, causing cab to shift on frame during turns

Fix: Classic Mopar truck disease—factory undercoating traps moisture. Proper fix requires cutting out rusted metal and welding in patch panels or full floor sections. Front floors: 8-10 hours per side including seam sealer and undercoat. Cab corners: 6-8 hours per side. This is body-shop work; most DIY-ers patch with pop-riveted sheet metal that fails in 2-3 years. Inspect before buying—if it's bad, walk away.

Estimated cost: $1,800-4,500

Typical onset: 60,000-90,000 mi

Symptoms: Clunking from front end when engaging 4WD or accelerating in 4WD, Vibration at 35-50 mph in 4WD only, smooths out in 2WD, Grinding or clicking during tight turns with 4WD engaged, Front driveshaft separation if catastrophic failure occurs

Fix: Front axle U-joints take severe angles due to short wheelbase and high ground clearance. Original single-cardan joints fail; upgrade to Spicer 5-760X or 5-297X. Front driveshaft: 1.5-2 hours. Inner axle shaft U-joints (inside knuckles): 4-5 hours per side, requires knuckle disassembly and seal replacement. Always replace in pairs. Check yokes for wear—grooved yokes will destroy new joints in 10,000 miles.

Estimated cost: $350-850

Typical onset: 70,000-110,000 mi

Symptoms: Power steering fluid puddle under left frame rail near steering box, Excessive play in steering wheel—1-2 inches before wheels respond, Wandering on highway, constant correction needed, 'drunk driver' feel, Groaning or whining from pump, especially when cold

Fix: Saginaw-style manual recirculating ball box on base models wears out sector shaft bushings; power boxes leak from input shaft seal. Adjustment can tighten play: 30 minutes, free. Rebuild kits available but fiddly: 3-4 hours for experienced tech. Most swap in a rebuilt box ($150-250 core charge refundable): 2 hours including alignment. Also inspect pitman arm, idler arm, and tie rod ends—these wear fast and cause same symptoms.

Estimated cost: $320-580

Symptoms: Fuel gauge reads empty even with full tank, or stuck at 1/4, Engine stalls or starves for fuel with more than 1/4 tank showing, Fuel pump runs dry, overheats, fails prematurely every 2-3 years, Visible rust flakes in fuel filter, brown/orange debris

Fix: Steel tank behind rear axle rusts from inside out—water condensation and ethanol accelerate it. Sending unit float arm corrodes and seizes; pickup tube (sock filter) clogs with rust scale. Drop tank (1.5-2 hours), replace sending unit and hoses. If tank is rusty inside, replace or have professionally cleaned and sealed ($200-300). Consider switching to in-tank electric pump setup from '90s Dodge truck for reliability—requires wiring work.

Estimated cost: $280-650