1980 CHEVROLET BLAZER

Typical onset: 80,000-140,000 mi

Symptoms: Slipping between 1st and 2nd gear, especially under load, Delayed engagement when shifting into drive or reverse, Burned transmission fluid smell, dark or metallic fluid, Loss of reverse or complete failure to move

Fix: Full rebuild required in most cases — 8-12 hours labor. These transmissions were marginal from the factory, especially behind the 350/400/454. Cooler lines rust through and starve the trans of fluid. Plan on pulling the trans, rebuilding with updated clutch packs and bands, replacing torque converter, and adding auxiliary cooler.

Estimated cost: $1,800-3,200

Typical onset: 120,000-180,000 mi

Symptoms: Heavy knock on cold start that quiets when warm (rod bearings), Low oil pressure at idle below 10 psi when hot, Blue smoke on deceleration or startup (rings), Excessive blowby visible at oil fill cap

Fix: Full engine rebuild or replacement needed — 18-28 hours labor depending on approach. These engines lived hard lives towing and idling. Main and rod bearings wear out, piston rings glaze and lose tension. Most cost-effective fix is a reman short block swap, but many owners go full rebuild with bore/hone, new pistons, crank grind, and all bearings. Expect machine shop work on top of labor.

Estimated cost: $3,500-6,500

Symptoms: Visible surface rust or perforation on frame rails behind cab, Body shifts or squeaks over bumps independent of frame, Doors misalign or won't latch properly, Cracks in cab corners or around rear window

Fix: Severity depends on climate — salt-belt trucks are often terminal by now. Body mounts rot out every 15-20 years regardless of mileage (2-4 hours to replace all). Frame rust requires professional assessment; surface scale is fixable, but holes in the C-channel mean it's scrap or a full frame-off restoration. POR-15 and patch panels only go so far.

Estimated cost: $400-800 for body mounts only; frame repair $2,000-8,000+

Symptoms: Rough idle, stalling at stop signs when warm, Black smoke and poor fuel economy (flooding), Hesitation or flat spot on acceleration, Fuel leaking from carb base or accelerator pump

Fix: The Quadrajet is reliable when clean but suffers from ethanol fuel damage and neglect. Most need a full rebuild kit installed — 3-5 hours for a thorough job including removal, disassembly, new gaskets, float adjustment, and proper tuning. Many owners swap to Edelbrock or Holley to avoid dealing with the Q-jet's complexity.

Estimated cost: $350-650

Typical onset: 100,000+ mi

Symptoms: Gear oil puddle under center of truck, Whining noise in 4WD that changes with speed, Difficulty shifting into or out of 4WD

Fix: Output shaft seals and input seal are common leak points — 2-4 hours depending on which seal. The NP205 is virtually bulletproof otherwise; the NP203 full-time case has a reputation for more issues. Reseal while you're in there, check for worn bearings. If the chain is stretched or gears are chipped, budget for a rebuild.

Estimated cost: $300-700 for seals; $1,200-2,000 for full rebuild

Symptoms: Engine dies after 15-20 minutes of driving, restarts when cool, Surging or stumbling under load, Fuel filters clog repeatedly with brown sediment, Visible rust flakes in fuel filter

Fix: Steel fuel tanks rust from the inside out on these trucks, especially if they sat. Requires tank removal and replacement (3-5 hours), plus new fuel lines if they're scaling internally. Many owners add inline filters before the pump and after. If the mechanical fuel pump diaphragm is compromised, fuel leaks into the crankcase — check oil level and smell.

Estimated cost: $400-900

Typical onset: 60,000-100,000 mi

Symptoms: Excessive play at steering wheel — more than 2 inches before wheels respond, Wandering on highway, constant correction needed, Clunking from steering when hitting bumps, Leaking gear oil from steering box

Fix: The recirculating-ball steering box can be adjusted for slop (free), but most need rebuild or replacement by now — 2-3 hours. Pitman arm, idler arm, and tie rod ends also wear out and compound the issue. Budget for a full front-end refresh including alignment. Overfilling or using the wrong fluid accelerates wear.

Estimated cost: $500-1,200