1998 FORD E-350

Typical onset: 60,000-150,000 mi

Symptoms: Sudden misfire with loud popping or hissing noise from engine, Check engine light with misfire codes (P030X), Loss of power, especially under load, Spark plug literally blown out of head, dangling by wire

Fix: Early 2-valve Triton V10s have inadequate thread engagement in the aluminum heads. Repair requires HeliCoil or TimeSert thread insert (2-3 hours labor per hole), but if multiple plugs have blown or threads are severely damaged, you're looking at head removal and machine work or replacement heads (12-16 hours labor). Preventive: replace plugs every 30k miles, never overtorque.

Estimated cost: $400-800 per cylinder for inserts; $3,500-5,500 for head removal/repair if damage is extensive

Typical onset: 80,000-140,000 mi

Symptoms: Transmission fluid in coolant reservoir (strawberry milkshake appearance), Coolant in transmission (transmission slipping, delayed engagement), Transmission overheating, Sudden transmission failure after coolant mixing

Fix: The cooler inside the radiator fails, allowing ATF and coolant to mix. Requires radiator replacement, complete transmission fluid flush (often multiple flushes), and sometimes full transmission rebuild if coolant damage is severe. If caught early (fluid in coolant only), flush and radiator swap is 4-5 hours. If transmission internals are contaminated, add 12-18 hours for rebuild.

Estimated cost: $800-1,200 for radiator and flush if caught early; $2,500-4,000 if transmission rebuild needed

Typical onset: 90,000-150,000 mi

Symptoms: Coolant leak visible at front or rear of engine valley, Overheating or coolant loss with no external leak, Rough idle or misfire from coolant in cylinders (severe cases), White smoke from exhaust if coolant enters combustion chamber

Fix: The plastic intake manifold and gaskets deteriorate. Replacement requires manifold removal, new gaskets, and often new coolant crossover tube. 6-8 hours labor. While you're in there, replace thermostat, hoses, and inspect spark plug threads.

Estimated cost: $900-1,500

Typical onset: 70,000-120,000 mi

Symptoms: Loud ticking or exhaust leak sound at startup, lessens when warm, Visible exhaust soot streaks on manifold, Broken or missing stud visible on inspection, Check engine light possible if O2 sensor reads incorrectly due to leak

Fix: Exhaust manifold studs corrode and snap off in the head. Repair involves drilling out broken studs and installing new ones—2-4 hours per side if studs come out clean, up to 8-10 hours if they break off flush and require head removal. Driver side is much tighter. Do both sides if one has failed.

Estimated cost: $600-1,200 per side; $2,000-3,000 if head removal required

Symptoms: No start, no fuel pump prime sound when key turned on, Intermittent stalling, especially when hot, Engine dies and won't restart until cool, No fuel pressure at rail

Fix: The fuel pump driver module (mounted on frame rail near fuel tank) overheats and fails. Replacement is straightforward, 1-1.5 hours, but diagnosis can take time if you're chasing an intermittent no-start. Common failure point on all Ford trucks of this era.

Estimated cost: $300-500

Symptoms: Cruise control inoperative, Brake pedal feels mushy or has excessive travel, Fluid leak at brake pedal area, Possible brake system contamination from leaking speed control switch

Fix: The speed control deactivation switch can leak brake fluid and fail. Ford issued recalls for this. Check if your VIN was included and if recall was completed. Replacement is simple, 0.5-1 hour, but verify brake system integrity if switch has been leaking.

Estimated cost: $150-300 if not covered by recall

Typical onset: 80,000-150,000 mi

Symptoms: Clunk when shifting from park to drive or reverse, Vibration at idle in gear, Excessive driveline movement visible under acceleration, Transmission sag visible on inspection

Fix: The rubber transmission mount deteriorates, especially on vans used for towing or heavy loads. Replacement is straightforward, 1.5-2 hours. Inspect engine mounts at the same time. Common wear item, not a catastrophic failure but annoying.

Estimated cost: $250-450