2000 CADILLAC DEVILLE

Typical onset: 80,000-130,000 mi

Symptoms: White smoke from exhaust on cold start, Coolant loss with no visible leaks, Oil in coolant reservoir or milky oil on dipstick, Overheating under load or in traffic, Engine misfires and rough idle as coolant enters cylinders

Fix: Northstar uses torque-to-yield head bolts that stretch and allow aluminum heads to lift. Proper fix requires heads off, resurface, new bolts, and quality gaskets—18-24 hours labor. Many shops avoid it. Budget alternatives like sealants or bolt inserts (HeliCoil kits) exist but are temporary. If coolant gets into cylinders long enough, you're looking at bearing damage and a full rebuild or short block.

Estimated cost: $3,500-6,500

Typical onset: 70,000-110,000 mi

Symptoms: Transmission fluid puddle under front of car, Pink or red fluid dripping near radiator, Slipping or delayed shifts from low fluid, Transmission overheating warning if fluid level drops significantly

Fix: The steel cooler lines rust through where they connect to the radiator or at crimped fittings. If you catch it early, replace lines only (2-3 hours). If it leaked long enough to starve the 4T80-E transmission, you're rebuilding or replacing the trans. Always flush and refill with fresh Dexron III after repair.

Estimated cost: $350-800 (lines only); $2,000-3,500 (if trans damaged)

Typical onset: 60,000-100,000 mi

Symptoms: Clunk or thud when shifting from Park to Drive or Reverse, Excessive vibration at idle in gear, Engine rocks noticeably during acceleration, Visible sagging or torn rubber on mount

Fix: The front transverse V8 puts stress on the rubber mounts. Right-side transmission mount deteriorates first. Straightforward replacement, 1.5-2 hours labor. Do all motor and trans mounts together if they're original—saves comebacks.

Estimated cost: $250-500

Symptoms: No-start with no spark—cranks but won't fire, Random stalling while driving, especially when hot, Engine cuts out then restarts after cooling, No codes or intermittent misfire codes

Fix: The ICM (ignition control module) under the coil packs fails from heat cycling. Part is behind the alternator on the passenger side—labor is 2-3 hours to access. NHTSA had a recall on ignition systems for this year; verify it was completed. Test module with scanner capable of reading misfire data before throwing parts.

Estimated cost: $400-700

Typical onset: 80,000-120,000 mi

Symptoms: Clunking or popping over bumps from front corners, Creaking or groaning when turning steering wheel while stopped, Steering feels notchy or catches at center

Fix: The upper strut mount bearings wear and get notchy. Not a safety issue but annoying. Replace strut mount assemblies—2 hours per side. Good time to do struts if they're original and showing any leakage.

Estimated cost: $400-700 (mounts only); $800-1,200 (with struts)

Symptoms: Cruise control doesn't engage when button pressed, Cruise disengages randomly without brake input, CRUISE light flashes or won't illuminate

Fix: Combination of brake switch issues, servo cable binding, or module faults. NHTSA recall existed for speed control—check completion. Diagnose with Tech 2 scanner to see which input is dropping out. Brake switch is the usual culprit (1 hour), servo cable or module replacement is 2-3 hours.

Estimated cost: $150-500