2021 FORD F-250

Typical onset: 60,000-120,000 mi

Symptoms: Knocking or ticking noise from lower engine block, especially cold start, Metal shavings or glitter in oil during changes, Low oil pressure warning at idle after warm-up, Catastrophic failure: sudden loss of power, severe knocking, engine seizure

Fix: This is a bottom-end failure requiring complete engine teardown. Most shops go straight to short block replacement or full engine rebuild. Figure 25-35 hours labor for short block swap, 40-50 hours for in-frame rebuild with machine work. Root cause is debated—oiling system design under high load, oil dilution from regens, or bearing material issues. Some failed units show oil starvation patterns on rod bearings.

Estimated cost: $15,000-25,000

Typical onset: 40,000-80,000 mi

Symptoms: Transmission fluid puddles under truck, often passenger side, Overheat warnings on dash during towing or heavy use, Pink or red fluid mixing with coolant in overflow tank (internal cooler breach), Transmission shifting erratically after getting hot

Fix: The integrated transmission oil cooler inside the radiator can develop internal leaks, contaminating coolant with ATF or vice versa—both are engine killers if not caught early. External lines also corrode at fittings. External line repair is 2-3 hours, but internal cooler breach means radiator replacement plus full fluid flushes on both systems. Critical to catch early before cross-contamination damages transmission or engine.

Estimated cost: $800-2,500

Typical onset: 80,000-150,000 mi

Symptoms: White smoke from exhaust on cold start that doesn't clear, Coolant consumption without visible external leaks, Bubbles or pressure in coolant overflow tank when running, Rough idle, misfires, loss of power under load, Oil that looks milky or coolant that looks oily

Fix: While not as epidemic as older 6.0L or 6.4L generations, the 6.7L still sees head gasket failures, particularly on heavily worked trucks. Job requires cab removal on Super Duty (8-10 hours just for cab lift), then 18-25 hours for gasket replacement on both heads. Always check for head warpage and pressure test. Many shops recommend ARP studs over TTY bolts on reassembly.

Estimated cost: $6,500-10,000

Typical onset: 50,000-90,000 mi

Symptoms: Clunk or thud when shifting from park to drive or reverse, Excessive driveline vibration, especially under throttle, Visible transmission sag or misalignment when inspected on lift, Harsh shifts or feeling like driveline is binding

Fix: The rubber transmission mount deteriorates faster than previous generations, likely due to increased torque from modern diesels and transmission weight. Easy diagnosis on a lift—look for torn rubber or collapsed mount. Replacement is straightforward: support transmission, unbolt old mount, install new. 1.5-2.5 hours labor. Do this before it causes driveline vibration damage.

Estimated cost: $350-600

Symptoms: Hard starting, especially in cold weather, Fuel puddles under driver side of engine, Loss of power, surging, or rough running, Check engine light with low fuel pressure codes (P0087, P0093)

Fix: The fuel filter housing on top of the engine develops leaks at the cap seal and drain valve. Worse, if water isn't drained regularly (every oil change in wet climates), contamination gets into the high-pressure fuel system and kills injectors. Filter changes are DIY-friendly but often neglected. Housing replacement when cracked is 2-3 hours. Always prime system properly after service or you'll be chasing air for hours.

Estimated cost: $400-800

Typical onset: 60,000-100,000 mi

Symptoms: DEF warning lights, messages about reduced engine power, Poor DEF fluid level readings or erratic gauge, Truck derates to 55 mph or 5 mph limp mode, DEF tank heater codes in cold climates

Fix: DEF quality matters—cheap or old fluid crystallizes in lines, sender, and injector. Cold climates expose DEF heater failures. Tank and sender replacement requires dropping the tank (3-4 hours), DEF injector replacement on exhaust side is another 4-6 hours. Prevention: use quality DEF, keep tank above 1/4 full, don't ignore warnings. Once you hit limp mode, you're towing it in.

Estimated cost: $1,200-3,500