1997 VOLVO S90

Typical onset: 80,000-150,000 mi

Symptoms: Coolant loss with no external leak visible, White smoke from exhaust especially on cold start, Milky oil on dipstick or oil cap, Overheating despite new thermostat and radiator, Sweet coolant smell from exhaust

Fix: The B6304 engine block has known porosity issues allowing coolant into cylinders or oil passages. Fix requires complete engine rebuild with block machining or replacement short block. Expect 20-30 labor hours for proper rebuild including machine work, gaskets, bearings, rings, and reassembly. Many shops won't touch it—replacement with used engine is common but risky.

Estimated cost: $4,500-8,000

Typical onset: 100,000-180,000 mi

Symptoms: Red ATF puddle under engine bay, Transmission slipping or erratic shifts, Rapid fluid loss leading to no movement, Fluid leaking near radiator area

Fix: Hard lines to cooler corrode and rupture, or cooler itself fails internally mixing ATF with coolant (death sentence for transmission). Replace lines, cooler, flush system, new ATF and filter. If coolant contaminated ATF, transmission rebuild likely needed. 3-5 hours for lines/cooler only, add 15-20 for transmission rebuild if contaminated.

Estimated cost: $600-1,200 (lines/cooler), $2,800-4,500 (if trans damaged)

Typical onset: 90,000-140,000 mi

Symptoms: Clunk when shifting from Park to Drive or Reverse, Vibration at idle in gear, Excessive driveline movement visible during acceleration, Gear selector feels loose or vague

Fix: Rubber mounts deteriorate allowing excessive transmission movement. Replace all mounts (typically 2-3 depending on setup). Straightforward job but requires supporting transmission. 2-3 labor hours.

Estimated cost: $400-700

Typical onset: 100,000-160,000 mi

Symptoms: External coolant leak from head/block mating surface, Compression loss in one or more cylinders, Rough idle and misfires, Overheating under load

Fix: Sometimes presents before full block failure but often discovered during investigation of coolant loss. Both heads should be removed, machined flat, new gaskets installed. If you're this far in, inspect block carefully for porosity—may need full rebuild anyway. 12-16 hours for head gasket job on both banks.

Estimated cost: $2,200-3,800

Symptoms: Hard starting especially when hot, Loss of power under acceleration, Stalling at idle or when coming to stop, Engine surging at highway speed

Fix: In-tank or inline fuel filter clogs from debris or old fuel. Many owners neglect filter changes (should be every 30k). Also check fuel pump and pressure regulator if filter doesn't solve it. Filter replacement is 1-1.5 hours, pump adds another 2-3 hours.

Estimated cost: $200-350 (filter), $600-900 (pump)

Typical onset: 120,000-200,000 mi

Symptoms: No-start condition suddenly, Stalling while driving with no restart, Intermittent stalling when engine hot, Check engine light with crank sensor code

Fix: Sensor mounted near crankshaft pulley fails from heat and vibration. Engine cranks but won't fire. Replace sensor and verify timing marks while you're there. 1-1.5 hours labor, inexpensive part.

Estimated cost: $180-320