2007 CHEVROLET SILVERADO 2500HD

Typical onset: 150,000-250,000 mi

Symptoms: excessive white or gray smoke on cold start, loss of power under load, loud knocking from deep in block, fuel dilution in oil, catastrophic failure with no warning if crack goes unnoticed

Fix: LMM pistons can crack at the bowl rim, especially cylinders 7 and 8. Overheating events, sustained high-EGT towing, or tuning accelerates this. Requires full engine-out rebuild with upgraded pistons, new rods, bearings, and often a crank if it's been damaged. 40-60 hours labor depending on cab-on vs cab-off approach. Some shops pull the cab for access, adding complexity.

Estimated cost: $12,000-20,000

Typical onset: 80,000-150,000 mi

Symptoms: transmission fluid leaking at radiator area, pink or milky transmission fluid indicating coolant contamination, overheating transmission, erratic shifting after coolant mixes in

Fix: The factory cooler inside the radiator develops internal leaks allowing coolant into the transmission or vice-versa. External lines rust through on salt-belt trucks. Catch it early and you replace cooler lines and flush the trans (3-4 hours). If coolant contaminates the Allison, you're looking at a full teardown, flush, and often torque converter and filter replacement to prevent destruction. Prevention: install an external trans cooler and bypass the radiator unit entirely.

Estimated cost: $400-1,200

Typical onset: 100,000-180,000 mi

Symptoms: clunk when shifting from park to drive or reverse, vibration at idle in gear, visible separation or tearing of rubber mount, transmission sag visible from underneath

Fix: The rubber transmission mount deteriorates from heat and load cycles, especially on trucks that tow heavy. It's a 2-3 hour job with a transmission jack to support the trans while swapping the mount. Cheap part, straightforward labor. Ignore it long enough and you'll stress the driveline and crossmember.

Estimated cost: $250-450

Typical onset: 120,000-200,000 mi

Symptoms: rough idle, white smoke on startup, hard starting when cold, check engine light with P0087 or balance rate codes, fuel in oil from leaking injector body seals

Fix: LMM injectors can fail internally or develop leaking body seals that dump fuel into the crankcase. Balance rates outside +/- 4 indicate a failing injector. Replacement is straightforward but requires removal of valve covers and fuel rails. 6-8 hours to do all eight injectors, most shops recommend doing them in pairs or all at once if mileage is high. Use OE Bosch injectors, not reman junk.

Estimated cost: $3,500-6,000

Typical onset: 90,000-140,000 mi

Symptoms: coolant weeping from weep hole on pump, squealing or grinding noise from front of engine, overheating, visible coolant leak below water pump area

Fix: The 6.0L water pump bearing fails or the seal goes, leading to coolant loss and overheating risk. It's a 3-4 hour job with fan clutch removal and accessory belt work. Not a huge deal but it will leave you stranded if ignored. Replace the thermostat at the same time since you're in there.

Estimated cost: $400-700

Typical onset: 60,000-120,000 mi

Symptoms: extended cranking before start, especially after sitting overnight, loss of prime, check engine light with low fuel rail pressure codes, visible fuel weeping at filter housing on frame rail

Fix: The filter head O-rings on top of the engine and the frame-mounted fuel filter housing both leak over time. Air gets sucked into the system causing hard starts and low-pressure codes. It's a 1-2 hour job to replace all the seals and prime the system. Do it during regular fuel filter service every 10-15k miles and you'll never have an issue.

Estimated cost: $200-400

Typical onset: 100,000-180,000 mi

Symptoms: white smoke from exhaust, coolant loss with no visible external leak, overheating, rough running, check engine light with EGR flow codes

Fix: The EGR cooler can crack internally, dumping coolant into the exhaust or intake. You'll see unexplained coolant loss and often a sweet smell from the exhaust. It's a 6-8 hour job to replace the cooler, and many owners opt for an EGR delete kit in non-emissions states. If you're in a state that tests, you're stuck replacing it with OE parts.

Estimated cost: $1,200-2,000