1990 MAZDA B2600

Typical onset: 80,000-140,000 mi

Symptoms: White smoke from exhaust on cold start, Coolant loss with no visible leaks, Milky oil on dipstick or cap, Overheating under load

Fix: Head gasket replacement requires cylinder head removal, resurfacing (often warped), and valve job. Budget 8-12 labor hours. If caught late, expect cracked head requiring replacement, adding another $300-600 in parts.

Estimated cost: $1,200-2,200

Typical onset: 120,000-180,000 mi

Symptoms: Knocking sound on cold start that fades when warm, Low oil pressure at idle (below 10 psi hot), Metallic rattling under acceleration, Metal flakes in oil during changes

Fix: Requires full bottom-end rebuild or short block replacement. If rods are scored, need crankshaft grind or replacement. Budget 16-24 hours for in-chassis rebuild, more if pulling engine. Often more cost-effective to swap in a used engine.

Estimated cost: $2,500-4,500

Typical onset: not mileage-driven

Symptoms: Red transmission fluid puddles under truck, Sudden loss of all gears (when fluid runs dry), Transmission overheating in towing or summer heat, Coolant in transmission pan (if internal cooler fails)

Fix: External cooler lines rust through at frame brackets. Replace both lines preventively (1-2 hours). Internal radiator cooler can leak coolant into ATF—requires radiator replacement plus full transmission fluid flush. If driven after mixing fluids, expect transmission rebuild.

Estimated cost: $150-400 (lines only), $800-1,500 (if radiator cooler contaminates transmission)

Typical onset: 70,000-120,000 mi

Symptoms: Clunk when shifting from park to drive, Excessive vibration at idle in gear, Visible sag of transmission tail—check from underneath, Shifter feels loose or notchy

Fix: Rubber transmission mount deteriorates, allowing drivetrain movement. Replacement is straightforward with a transmission jack (1-1.5 hours). Often done with engine mounts at same time for efficiency.

Estimated cost: $120-250

Typical onset: not mileage-driven

Symptoms: Hard starting after sitting overnight, Stalling at idle when warm, Loss of power uphill or under load, Surging at highway speeds

Fix: Inline fuel filter under truck rusts internally or clogs from tank sediment. Many trucks still run original filters. Replace every 30,000 mi or immediately if symptoms appear (0.5 hours). Also inspect fuel pump sock in tank—common cause if filter replacement doesn't resolve issues.

Estimated cost: $80-150

Typical onset: not mileage-driven

Symptoms: Black smoke at startup, Gas smell in cab or garage, Rough idle that smooths at higher RPM, Stalling when coming to a stop

Fix: The feedback carburetor is prone to float needle wear and vacuum leak issues. Full rebuild kit with float adjustment runs 3-4 hours. If choke pulloff or dashpot diaphragms are torn, replace separately. Vacuum routing diagram under hood is critical—many trucks have wrong hoses.

Estimated cost: $350-650