1979 OLDSMOBILE 98

Typical onset: 50,000-80,000 mi

Symptoms: White smoke from exhaust, Coolant loss with no external leaks, Hard starting when warm, Metal shavings in oil, Sudden loss of compression

Fix: The Olds 350 diesel used gasoline engine block architecture with inadequate head bolts and no water separator, leading to head gasket failure, cracked blocks, and injector pump destruction. Fix requires complete engine replacement or conversion to gas V8. Engine swap: 20-30 hours labor including wiring and exhaust modifications.

Estimated cost: $3,500-6,500

Typical onset: 80,000-120,000 mi

Symptoms: Rattling noise on cold start that diminishes when warm, Check engine light or rough idle, Difficulty starting, Loss of power at higher RPMs

Fix: Nylon timing gear teeth strip or the chain stretches excessively on 350 and 403 engines due to inadequate oiling or deferred maintenance. Requires front cover removal, new timing set with steel gears, and oil pump inspection. 6-8 hours labor.

Estimated cost: $650-1,200

Symptoms: Hesitation on acceleration, Black smoke from exhaust, Flooding and hard starting, Stalling when cold or at idle, Poor fuel economy below 10 mpg

Fix: The Q-jet has aged rubber components, clogged passages, and worn throttle shafts causing air leaks. Modern ethanol fuel accelerates deterioration. Professional rebuild with modern gasket kit: 3-4 hours. Many shops won't touch them anymore; specialist carb rebuilders charge premium.

Estimated cost: $350-650

Typical onset: 100,000-150,000 mi

Symptoms: Delay in 2-3 seconds before reverse engagement, Harsh 1-2 shift when cold, Slipping on acceleration, Pink or burnt-smelling fluid

Fix: Worn pump seals, hardened seals, or valve body issues common with age. Full rebuild with modern seals and clutches: 12-16 hours. THM 400 is robust but requires fresh fluid every 30k. Partial fixes rarely last.

Estimated cost: $1,800-2,800

Symptoms: Visible rust perforation in rear quarters and rocker panels, Body separation from frame near mount points, Sagging rear body section, Doors misaligned or hard to close

Fix: Body-on-frame design with rubber mounts that rot and frames that rust through at crossmembers, especially behind rear wheels. Body mount replacement: 8-12 hours. Frame section repair requires welding certification and structural assessment. Many cars are totaled structurally despite running drivetrains.

Estimated cost: $1,200-3,500

Typical onset: 60,000-100,000 mi

Symptoms: Whining noise when turning, Fluid puddles under front end, Heavy steering effort when cold, Low fluid reservoir despite top-offs

Fix: Saginaw pump seals and steering box seals harden with age. Pump replacement: 2 hours. Steering box rebuild or replacement: 4-6 hours with alignment. These leak on almost every survivor car; keep fluid topped to prevent pump failure.

Estimated cost: $400-900

Typical onset: 90,000-130,000 mi

Symptoms: Oil spots on driveway after sitting, Oil coating on transmission bellhousing, Smoke from exhaust manifolds on startup, Dropping 1 quart every 500-800 miles

Fix: Two-piece rear main seal design prone to leaking as rope seal hardens. Requires transmission removal. 8-10 hours labor. Not urgent unless leak is severe; many owners just keep oil topped off. Modern rope seal material lasts longer than original.

Estimated cost: $650-1,100