1978 OLDSMOBILE CUTLASS

Typical onset: 80,000-120,000 mi

Symptoms: Rattling noise on cold starts that fades as oil pressure builds, Rough idle or misfiring from jumped timing, Check engine light or ignition timing that won't stay set, Loss of power, especially under acceleration

Fix: Requires timing cover removal, new chain/gears/tensioner. On small-blocks this is 4-6 hours; add time if water pump or oil pan gaskets are done simultaneously. Replace front seal and consider doing the oil pump while you're in there.

Estimated cost: $600-1,200

Typical onset: 40,000-80,000 mi

Symptoms: Head gasket failure with coolant in oil or vice versa, Cracked cylinder heads from inadequate head bolt design, Harmonic balancer walking off the crankshaft, Injection pump failure causing no-start or severe smoking

Fix: This engine is fundamentally flawed—GM converted a gas V8 without proper strengthening. Head gasket jobs fail repeatedly. Real fix is a small-block gas V8 swap (40-60 hours for complete conversion including wiring, exhaust, fuel system). Parts alone run $3,000-5,000.

Estimated cost: $5,000-9,000

Symptoms: Hard starting when cold or hot, Black smoke from overly rich mixture, Hesitation or stumble on acceleration, Poor fuel economy (sub-10 mpg in city driving), Flooding from stuck float or needle valve

Fix: Rebuild kits run $40-80 and take 2-3 hours for someone who knows Quadrajets. Common issues: accelerator pump diaphragm, float adjustment, secondary air valve binding. Many shops just replace with remanufactured unit rather than rebuild.

Estimated cost: $200-500

Symptoms: Visible rust perforation in trunk floor and rear seat footwells, Sagging rear suspension from rotted frame rail mounts, Quarter panel rust behind rear wheels, Spongy floor under carpet near rocker panels

Fix: Floor pan replacement requires interior removal and welding (12-20 hours per side). Frame rail repairs may require subframe connectors or full replacement. Quarter panels need cutting and welding (16-24 hours per side). Rustbelt cars often aren't worth fixing if structural.

Estimated cost: $2,500-8,000

Typical onset: 100,000+ mi

Symptoms: Oil drips or puddles after parking, Oil coating on transmission bellhousing, Visible seepage around oil pan edges, Low oil warnings if leak is severe

Fix: Rear main seal requires transmission removal (5-7 hours on V8s). Two-piece rope seal is original; many convert to one-piece neoprene. Oil pan on small-blocks can often be done without removing engine but crossmember may need dropping (3-4 hours).

Estimated cost: $400-900

Typical onset: 60,000-90,000 mi

Symptoms: Slipping in 2nd or 3rd gear under load, No forward gears or delayed engagement, Burnt transmission fluid smell, Harsh or banging shifts

Fix: The THM200 (lightweight metric transmission) behind V8s was undersized and failure-prone. Rebuild runs 8-12 hours but many swap to THM350 for reliability (requires driveshaft shortening and crossmember work). Check casting—THM200C was improved but still marginal.

Estimated cost: $1,200-2,500

Typical onset: 80,000+ mi

Symptoms: Excessive play in steering wheel (more than 2 inches), Wandering on highway requiring constant correction, Clunking when turning lock-to-lock, Leaking power steering fluid from sector shaft seal

Fix: Saginaw 605 steering box can be adjusted for lash but often needs rebuild or replacement (2-3 hours). Also check idler arm and pitman arm—these wear simultaneously. Full front-end refresh with upper/lower ball joints, tie rods, and steering box runs 6-8 hours.

Estimated cost: $300-800