1958 CADILLAC SEVILLE

Typical onset: Original engines typically need work regardless of mileage due to age—cylinder wear, ring sealing loss, bearing clearances

Symptoms: Excessive oil consumption (1+ quart per 500 miles), Low compression across multiple cylinders, Heavy blue smoke on startup and acceleration, Rod knock or main bearing rumble at idle

Fix: Complete engine rebuild including bore/hone cylinders, new pistons/rings, main and rod bearings, valve job with new guides and seals. Machine shop work plus 40-50 hours removal, rebuild, reinstall. These 365s have good parts availability but require experienced rebuilder familiar with pre-'59 Cadillac tolerances.

Estimated cost: $8,000-15,000

Symptoms: Slipping between gears, especially 2nd to 3rd, Delayed engagement when shifting to Drive, No reverse or intermittent reverse, Metal particles in fluid or burnt smell

Fix: The 4-speed Hydra-Matic in these is robust when fresh but fails hard after decades. Full rebuild requires specialized knowledge—these aren't like modern automatics. Clutch packs, bands, seals, and often the oil cooler lines. 20-30 hours for R&R and rebuild. Finding a shop that still works on these is the real challenge.

Estimated cost: $3,500-6,500

Symptoms: Transmission fluid leaking from steel lines near radiator, Puddles of red fluid under front of car, Low transmission fluid level causing slipping, Visible rust perforation on cooler lines

Fix: The steel transmission cooler lines rust through after decades of road salt and moisture. Replacement with proper pre-bent lines or custom fabrication. Often discover this when doing transmission service. 3-5 hours to replace both lines and refill system properly.

Estimated cost: $400-800

Symptoms: Hard starting or long cranking before firing, Stalling when hot after sitting 10-15 minutes, Fuel smell in garage or around tank, Rough idle and hesitation under load

Fix: Original fuel tanks rust from inside, sending rust and sediment through the system. Ethanol fuel destroys old rubber lines and Carter carburetor components. Typical fix: tank clean/coat or replace, new fuel pump, rebuild 4-barrel carb, replace all rubber fuel lines. 12-16 hours for thorough job.

Estimated cost: $1,200-2,500

Symptoms: Loud valve clatter on cold start for 30+ seconds, Oil leaks from valve covers and intake manifold, Low oil pressure at hot idle (under 15 psi), Ticking that doesn't quiet down with RPM

Fix: Even if the bottom end is solid, these engines develop valve guide wear, lifter issues, and gasket leaks. Complete valve job with new guides, seals, lifters, and timing chain. All gaskets including intake manifold. 25-35 hours with head removal and resurfacing.

Estimated cost: $3,000-5,500

Symptoms: Deep knocking sound from bottom of engine at idle, Oil pressure drops significantly when warm, Metallic debris on magnetic drain plug, Knock increases with throttle application

Fix: When main or rod bearings are gone, crankshaft often needs grinding or replacement. Full teardown required. If crank needs 0.030" undersize or more, finding bearings gets harder. This typically becomes part of a complete engine rebuild scenario. 50+ hours all-in.

Estimated cost: $10,000-18,000