1979 BUICK SKYHAWK

Typical onset: 90,000-140,000 mi

Symptoms: Severe knocking from crankcase, especially when cold or under load, Metallic grinding noise at idle, Oil pressure drops significantly or warning light flickers, Metal shavings visible in oil or on magnetic drain plug

Fix: The 231 V6 is notorious for crankshaft and main bearing wear due to undersized journals and marginal oiling. Repair requires engine removal (6-8 hours labor given tight H-body engine bay), crankshaft grinding or replacement, main bearing set, and full gasket kit. Most shops recommend short block replacement or reman long block instead of in-frame rebuild given access constraints and age of surrounding components.

Estimated cost: $2,800-4,500

Typical onset: 60,000-110,000 mi

Symptoms: Transmission fluid leaking from rubber hoses at radiator, Harsh or delayed shifts when transmission is hot, Burned transmission fluid smell or dark/burnt ATF on dipstick, Transmission slipping in higher gears after extended driving

Fix: The TH200/TH350 automatics in these cars run hot, and the rubber cooler lines deteriorate, causing leaks and inadequate cooling. Replace both hard and flex lines (2-3 hours), flush radiator cooler circuit, and change ATF. If caught early, transmission survives; if overheated extensively, expect rebuild or replacement adding another $1,200-2,000.

Estimated cost: $350-650

Typical onset: 80,000-130,000 mi

Symptoms: Blue smoke from exhaust on startup and acceleration, Oil consumption exceeding 1 quart per 500-800 miles, Fouled spark plugs on one or more cylinders, Loss of compression evident in cylinder leak-down test

Fix: The 231 V6 uses soft piston rings that wear prematurely, especially if oil changes were neglected. In-frame ring replacement requires head removal, cylinder honing, new rings, and rod bearings (12-15 hours). Given the engine-out complexity in the H-body and likelihood of other wear, most techs push for short block or reman long block instead unless compression numbers are still decent across all cylinders.

Estimated cost: $1,800-3,200

Symptoms: Engine stumbles, hesitates, or dies under acceleration, Difficult starting after sitting, especially in humid climates, Fuel starvation symptoms at highway speeds, Rust particles visible in inline fuel filter

Fix: Original steel fuel tanks and lines rust internally after 40+ years, sending debris into the carb or fuel pump. Replace inline fuel filter first ($35 + 0.5 hour labor). If problem persists, tank needs dropping, cleaning, or replacement (4-5 hours), and all rubber fuel line replaced. Consider adding inline filter before mechanical pump as cheap insurance.

Estimated cost: $80-850

Typical onset: 50,000-90,000 mi

Symptoms: Clunking when shifting from park to drive or reverse, Excessive vibration at idle in gear, Transmission tail housing sits visibly low, Shifter feels loose or has excessive play

Fix: The rubber transmission mount degrades with heat and age, allowing excessive drivetrain movement. Replacement is straightforward: support trans with jack, unbolt old mount, install new (1.5-2 hours). Inspect engine mounts simultaneously—if one is collapsed, others are close behind.

Estimated cost: $180-320

Symptoms: Rough idle, stalling at stoplights, Black smoke indicating rich condition, Poor fuel economy (under 15 mpg city), Hesitation off idle or flat spot during acceleration

Fix: The Rochester 2GC/2SE carbs on these engines wear at throttle shafts and float needle seats, causing vacuum leaks and flooding. A thorough rebuild with kit runs 3-4 hours including removal, disassembly, replacement of all gaskets/seals/needles, and reinstallation with tuning. Alternatively, reman carb swap takes 2 hours but costs more upfront.

Estimated cost: $280-550