1978 CADILLAC ELDORADO

Typical onset: 80,000-150,000 mi

Symptoms: blue smoke on startup and acceleration, oil level dropping 1+ quart per 500 miles, fouled spark plugs, loss of power under load

Fix: The 425 V8 has soft piston rings that wear prematurely. Proper fix requires full engine teardown, honing cylinders, new rings on all pistons (or complete piston replacement if cylinder taper exceeds .003). Expect 25-35 hours labor for in-chassis ring job, 40-50 hours if pulling engine for full rebuild with bearings and machine work.

Estimated cost: $3,500-7,500

Typical onset: 60,000-120,000 mi

Symptoms: milky pink transmission fluid, transmission slipping or delayed engagement, overheating transmission, coolant loss with no external leaks, strawberry milkshake appearance in radiator

Fix: The internal transmission cooler in the radiator develops pinhole leaks, allowing coolant and ATF to mix. If caught early, replace radiator and flush transmission (4-6 hours). If driven after mixing, transmission internals are damaged and require full rebuild or replacement (20-30 hours). Critical to inspect cooler lines and external cooler if equipped.

Estimated cost: $800-1,200 (cooler only), $3,000-5,000 (with transmission rebuild)

Typical onset: 50,000-100,000 mi

Symptoms: severe clunking when shifting from Park to Drive, vibration at idle that changes with gear selection, visible sagging of engine/transaxle assembly, CV joint binding or clicking on turns

Fix: The FWD drivetrain on these cars uses rubber mounts that deteriorate and collapse, especially the rear transmission mount. Replacement requires supporting the transaxle from below, removing crossmember (2-3 hours per mount). Failed mounts cause driveline misalignment that accelerates CV joint and differential wear.

Estimated cost: $400-800

Typical onset: 70,000-130,000 mi

Symptoms: external coolant leaks at head/block junction, white smoke from exhaust, bubbling in coolant reservoir, engine overheating, rough idle or misfire on specific cylinders

Fix: The 425 V8 head gaskets fail from age and thermal cycling. Both heads should be done together with resurfacing. Requires removing massive intake manifold, exhaust manifolds, and accessories (18-24 hours). Check for warped heads and cracked cylinders during disassembly. Often combined with timing chain replacement since you're already in there.

Estimated cost: $2,500-4,000

Symptoms: hard starting after sitting, stalling at idle, hesitation or stumbling on acceleration, dying when coming to a stop

Fix: Ethanol fuel degrades quickly in these carbureted systems. Old fuel leaves varnish in carburetor passages, fuel lines, and clogs the inline filter. Replace fuel filter (0.5 hours), drain and clean tank if heavily contaminated (3-4 hours), rebuild or replace carburetor (4-6 hours). Often needs full fuel system service after extended storage.

Estimated cost: $150-300 (filter/cleaning), $600-1,200 (carburetor rebuild)

Typical onset: 120,000-200,000 mi

Symptoms: deep knocking sound from bottom end that increases with RPM, low oil pressure at idle, metallic rattling on cold starts, severe vibration through chassis

Fix: High-mileage 425 engines develop worn main bearings, often from years of inadequate oil changes or using wrong viscosity oil. Requires complete engine removal and teardown (40-50 hours). Crankshaft must be removed, measured, and either polished or replaced. Machine shop work adds days. Often discover damaged block requiring replacement or sleeving.

Estimated cost: $5,000-9,000