1990 CHEVROLET SUBURBAN

Typical onset: 80,000-150,000 mi

Symptoms: Transmission fluid in coolant or vice versa (strawberry milkshake in reservoir), Transmission slipping or delayed engagement after mixing fluids, External cooler line leaks at radiator or fittings, Overheating transmission with towing or highway use

Fix: Replace radiator with integrated trans cooler, flush both cooling and transmission systems completely, often replace torque converter if contamination occurred. 6-8 hours labor for full job including flush procedures.

Estimated cost: $800-1,500

Typical onset: 100,000-180,000 mi

Symptoms: Raw fuel smell from engine bay or exhaust, Black smoke on startup, Rough idle and poor fuel economy (drops 2-4 mpg), Fuel in vacuum line to regulator, Hard starting when engine is hot

Fix: Replace fuel pressure regulator on throttle body, inspect injectors for leakage. Simple job, 1-1.5 hours. Often done with full TBI service including injector cleaning.

Estimated cost: $150-350

Typical onset: 150,000-250,000 mi

Symptoms: Burning 1 quart per 500-1,000 miles, Blue smoke on deceleration or startup, Fouled spark plugs on cylinders 2, 4, 6, 8 (common pattern), Low compression readings (below 120 psi), Carbon buildup visible in throttle body

Fix: Full top-end rebuild with new rings, honing, valve job. If bore taper exceeds 0.003", needs bore and oversized pistons. Machine work plus 16-20 hours labor. Many owners opt for reman short block at this point.

Estimated cost: $2,200-4,500

Typical onset: 80,000-120,000 mi

Symptoms: Clunking over bumps in front end, Wandering or loose steering feel, Uneven tire wear on inside edges, Play visible when prying on tire at 12 and 6 o'clock, Grease boot torn or collapsed

Fix: Replace all four ball joints per axle (uppers often pressed in, lowers bolt-on or pressed depending on model year crossover). Alignment mandatory. 4-6 hours per side including alignment.

Estimated cost: $800-1,400

Typical onset: 100,000-180,000 mi

Symptoms: No-start or stumbling under load, Fuel pressure below 9-13 psi spec at TBI, Whining noise from fuel tank, Inaccurate or dead fuel gauge (sending unit), Stalling in hot weather or with low fuel level

Fix: Drop 40-gallon fuel tank (usually full of gas), replace pump module. Tanks rust internally on these, inspect carefully. 3-4 hours labor, more if tank straps are rusted.

Estimated cost: $400-750

Typical onset: 60,000-120,000 mi

Symptoms: No-start when engine is hot, starts fine cold, Misfiring under load or acceleration, Stalling in traffic or after extended idling, Carbon tracking visible inside distributor cap, Ignition module fails when heat-soaked

Fix: Replace cap, rotor, ignition module, and plug wires as a set. Module often culprit for hot no-start. 1.5-2 hours including distributor timing check.

Estimated cost: $250-500

Typical onset: 120,000-200,000 mi

Symptoms: Oil spots on driveway, concentrated at rear of engine, Oil coating on flywheel housing and starter, Visible seepage at oil pan rail or timing cover, Burning oil smell from exhaust heat

Fix: Rear main seal requires transmission removal, 8-10 hours. Oil pan gasket can be done with engine in place but crossmember and exhaust complicate access, 4-5 hours. Often batched together.

Estimated cost: $600-1,200

Typical onset: 100,000-180,000 mi

Symptoms: Soft or spongy brake pedal that doesn't improve with bleeding, Pedal slowly sinks to floor under constant pressure, Rear brakes locking up prematurely (proportioning valve), Fluid leaking from master cylinder rear seal into booster, Recall-related rotor cracking on heavy braking

Fix: Replace master cylinder and bench-bleed before install. Check proportioning valve for corrosion. If booster is fluid-soaked, replace it too. 2-3 hours labor plus full brake system bleed.

Estimated cost: $300-700