2002 CADILLAC DTS

Typical onset: 80,000-150,000 mi

Symptoms: White smoke from exhaust on cold start, Coolant loss with no visible leaks, Overheating or fluctuating temp gauge, Milky oil or coolant in oil, Rough idle or misfires after warming up

Fix: The Northstar uses torque-to-yield head bolts that pull threads out of the aluminum block over time. Proper fix requires removing heads, time-sert thread inserts in all bolt holes, new head gaskets, and machine work if heads are warped. 18-24 labor hours for both heads. Half-measures like stop-leak rarely last more than a few months.

Estimated cost: $3,500-6,000

Typical onset: 70,000-130,000 mi

Symptoms: Transmission fluid pooling under vehicle, Pink fluid dripping near radiator area, Low trans fluid warning or slipping shifts, Sudden loss of all gears if catastrophic rupture

Fix: Steel cooler lines rust through where they run along the subframe, especially in salt-belt states. Replace both lines even if only one is leaking — the other is right behind it. Some techs fab stainless replacements. 2-3 hours labor plus fluid refill and leak check.

Estimated cost: $400-800

Typical onset: 60,000-110,000 mi

Symptoms: Clunk or thud on acceleration or deceleration, Vibration at idle in Drive, Visible engine movement when revving in Park, Harsh engagement into gear

Fix: The hydraulic front mount and rear transmission mount deteriorate, allowing excessive powertrain movement. Replace both mounts as a set since they wear together. 2-3 hours labor with motor support equipment.

Estimated cost: $500-900

Typical onset: 90,000-140,000 mi

Symptoms: Coolant seepage at rear of engine near firewall, Sweet smell in cabin or under hood, Slow coolant loss without obvious external leak, Steam from back of engine bay

Fix: Plastic coolant crossover pipes and intake manifold gaskets fail, often hidden behind the engine. Requires removing upper intake plenum and various accessories to access. 4-6 hours labor. Do coolant elbows and thermostat housing at same time if original.

Estimated cost: $800-1,400

Typical onset: 80,000-120,000 mi

Symptoms: Rear sags overnight or after sitting, Compressor runs excessively or constantly, Suspension warning message on DIC, Uneven ride height side-to-side

Fix: Air ride compressor wears out, or air lines crack at fittings. Compressor replacement is 2-3 hours. Many owners convert to passive springs (Arnott kit or similar) to eliminate system entirely — roughly same labor, permanent fix.

Estimated cost: $600-1,200

Typical onset: 100,000-150,000 mi

Symptoms: Hard starting after sitting, Stumble or hesitation under load, Stalling at idle after deceleration, Check engine light with lean codes

Fix: In-tank fuel pump and external inline filter both fail. Filter is easy (30 minutes), pump requires dropping tank and is often caught late when fuel starvation codes appear. 2-3 hours for pump. Replace filter every 30k as preventive — often skipped.

Estimated cost: $400-900

Typical onset: any

Symptoms: Gear indicator shows wrong gear, Speedometer erratic or dead, ABS or traction control faults, Won't shift out of Park without override

Fix: Transmission range sensor or vehicle speed sensor fails. Range sensor is external on trans, 1 hour. VSS or internal speed sensor requires pan drop, 2-3 hours. Often causes nuisance codes but rarely leaves you stranded.

Estimated cost: $250-600