1984 CHEVROLET BLAZER

Typical onset: 80,000-140,000 mi

Symptoms: Slipping or flare on 3-4 upshift, No overdrive engagement or drops out under load, Burnt fluid smell, dark or metallic debris in pan, Shudder or clunk when downshifting

Fix: TH700R4 was notorious for weak 3-4 clutch packs and inadequate factory cooling. Rebuild with updated hard parts, add auxiliary cooler. 8-12 labor hours for R&R and rebuild if outsourced; experienced techs can do in-chassis valve body work in 4-5 hours but full rebuild is safer.

Estimated cost: $1,800-3,200

Symptoms: Hard starting when hot, floods easily, Black smoke at idle or hesitation off-idle, Fuel smell in cab or engine bay after shutoff, Erratic idle speed, hunting between 500-1200 RPM

Fix: Q-jet carbs of this era suffer from warped choke housings, leaking accelerator pump seals, and clogged idle circuits. Rebuild kit plus choke stat and careful float adjustment. 3-4 hours for experienced carb tech; many shops now outsource or recommend Edelbrock swap instead.

Estimated cost: $350-750

Symptoms: Visible rust perforation on frame rails behind cab mounts, Body bounce or cab movement independent of frame over bumps, Cracked or crumbling rubber body mounts, Door alignment issues, gaps changing with load

Fix: Snow-belt trucks commonly rust through frame at rear spring hangers and behind cab mounts. Body mounts (12 total) dry-rot even in dry climates. Inspect before purchase—catastrophic frame rust is economic total-loss. Body mount replacement is 6-8 hours; frame section welding requires certified welder and inspection, not DIY-friendly.

Estimated cost: $600-1,200

Typical onset: 60,000-100,000 mi

Symptoms: Stalling when hot, restarts after cooling, Fuel pressure drops below 5 psi, stumbles under load, Visible fuel weeping from pump diaphragm, Inaccurate or dead fuel gauge (sending unit)

Fix: Mechanical pump on block runs hot and diaphragms fail; cheap part but access can be tight on passenger side of block. Sending unit in tank requires tank drop. Pump replacement is 1-2 hours; sending unit adds 2-3 hours for tank drop, often bundled with new fuel filter and hoses. Many owners retrofit electric pump in-tank or frame-mount.

Estimated cost: $250-600

Typical onset: 90,000-150,000 mi

Symptoms: Grinding or popping when engaging 4WD, Jumps out of 4-Low or 4-High under load, Front axle won't engage or engages intermittently, Fluid leak from case or shift linkage

Fix: NP208 chain-drive cases wear shift forks, detent springs, and mode fork pads. Shift linkage also loosens at frame pivot. Linkage adjustment is 0.5 hours; internal rebuild requires case removal (4-5 hours) plus rebuild time. Many upgrade to NP241 or full case swap from later model.

Estimated cost: $800-1,600

Typical onset: 100,000-180,000 mi

Symptoms: Ticking or tapping on cold start that persists after warm-up, Loss of power, rough idle, or single-cylinder misfire, Metallic clatter at valve covers, Oil pressure drops if cam lobe wipes out

Fix: Hydraulic lifters collapse from wear or sludge buildup; worn cam lobes follow if oil changes were skipped. Lifter replacement requires intake manifold removal on these engines, 6-8 hours including adjustment and gaskets. If cam is worn, add camshaft R&R (12-16 hours total) or consider engine rebuild at that point.

Estimated cost: $900-2,400

Typical onset: 120,000-200,000 mi

Symptoms: Hard starting or no-start, especially cold, Black smoke, loss of power under load, Fuel in oil (dilution from internal leak), Rough idle, uneven cylinder contribution

Fix: Stanadyne DB2 pumps on 6.2L are robust but eventually wear internal seals and advance mechanism. Pump replacement is 4-6 hours including timing and priming; rebuilt pumps widely available. Often coincides with glow plug or controller issues—diagnose electrical first. Fuel quality and filter maintenance critical to pump longevity.

Estimated cost: $1,200-2,200