1968 BUICK GS

Typical onset: 80,000-120,000 mi

Symptoms: Slipping between gears, especially 2nd to 3rd, Delayed engagement when shifting into Drive or Reverse, Burnt transmission fluid smell and dark or metallic fluid, Loss of forward gears while reverse still works

Fix: Full rebuild with new clutches, bands, seals, and torque converter. Typical rebuild takes 12-16 labor hours. Most survivors need this if not already done. Also replace rubber transmission mount during R&R as they crack with age.

Estimated cost: $2,200-3,800

Typical onset: 60,000-100,000 mi

Symptoms: White smoke from exhaust, especially on cold starts, Coolant mysteriously disappearing without visible leaks, Milky oil on dipstick or oil cap, Overheating under load or in traffic

Fix: Both heads off, resurface if warped, new gaskets and head bolts. These nailhead-derivative engines weren't prone to this when new, but decades of heat cycling and improper coolant maintenance take their toll. Budget 18-22 hours labor. Always pressure-test the block and inspect for cracks while apart.

Estimated cost: $1,800-3,200

Typical onset: 100,000+ mi

Symptoms: Deep knocking noise from bottom end, worse under load, Low oil pressure at idle when fully warmed up, Metallic debris in oil pan or filter, Visible crank endplay or up-down movement at harmonic balancer

Fix: Engine must come out for crank inspection and bearing replacement. Often the crank needs grinding or replacement. If pistons and rings are worn too, it becomes a full rebuild. Expect 30-40 hours for complete teardown, machine work, and reassembly.

Estimated cost: $4,500-8,000

Typical onset: 80,000+ mi

Symptoms: Blue smoke on deceleration or at startup, Excessive crankcase pressure (oil filler cap pops off), Heavy oil consumption, 1 quart per 500-800 miles, Wet, oily spark plugs

Fix: Requires engine teardown for new rings, honing cylinders, and often new pistons if ring lands are damaged. Ridge-reaming the cylinders is mandatory. If cylinders are scored, boring and oversize pistons needed. Plan for 25-35 hours including R&R.

Estimated cost: $3,500-6,500

Symptoms: Transmission fluid leaking at radiator connections, Fluid spraying onto exhaust manifolds creating smoke, Rapid fluid loss and subsequent transmission slipping, Rust-through of original steel lines, especially at fittings

Fix: Replace both lines from transmission to radiator-mounted cooler. Original steel lines rust from the inside out after 50+ years. Upgrade to braided stainless or pre-bent steel with proper routing. Also inspect radiator-side fittings for leaks. 2-3 hours labor.

Estimated cost: $250-500

Symptoms: Hard starting after sitting, especially when warm, Stumbling or dying at idle after initial startup, Fuel starvation under acceleration, Visible rust or debris in fuel filter or carburetor bowl

Fix: Old gas varnish clogs the Rochester 4-barrel carburetor and fuel lines. Drop the tank, clean or replace it, blow out all lines, rebuild or replace carburetor, install inline filter. Survivors often sat for years with bad gas. 6-10 hours depending on tank condition.

Estimated cost: $600-1,400