2007 JEEP GRAND CHEROKEE SRT8

Typical onset: 80,000-120,000 mi

Symptoms: Severe misfires on multiple cylinders, Loss of compression, Metal debris in oil, Clattering noise from cylinder head, Check engine light with P0300-series codes

Fix: The 6.1L Hemi suffers from valve seats dropping out of the heads, especially on cylinders 3 and 5. Once it starts, metal contaminates the entire engine. Requires complete engine rebuild with hardened seat inserts, or short block replacement if bearings are scored. Budget 40-50 labor hours for full rebuild.

Estimated cost: $8,000-15,000

Typical onset: 60,000-100,000 mi

Symptoms: Pink milkshake in coolant reservoir, Transmission slipping or delayed engagement, Overheating transmission, Coolant loss with no external leaks, Trans fluid in radiator

Fix: The internal trans cooler in the radiator fails, allowing coolant and ATF to mix. This destroys the transmission within days if driven. Requires new radiator, complete transmission flush or rebuild, and coolant system flush. If caught early (just cooler leak), 8-10 hours. If trans is damaged, add 15-20 hours for rebuild.

Estimated cost: $1,200-2,500 (cooler only), $4,000-6,500 (with trans rebuild)

Typical onset: 70,000-110,000 mi

Symptoms: Severe clunk when shifting from Park to Drive, Vibration at idle in gear, Visible engine movement when revving, Chassis shudder on acceleration

Fix: The NAG1 transmission mount tears from the torque of the 6.1L. Allows excessive drivetrain movement that accelerates wear on driveshaft and transfer case. Replace all engine and trans mounts as a set. 3-4 labor hours.

Estimated cost: $600-1,200

Typical onset: 90,000-130,000 mi

Symptoms: Hesitation or stumble under hard acceleration, Loss of power above 4,000 RPM, Long cranking before start, Lean codes (P0171/P0174), Fuel pressure drops under load

Fix: High fuel demands of the SRT8 expose marginal fuel systems. In-tank filter sock clogs, and pump weakens. Requires fuel tank drop and pump module replacement. 4-5 labor hours.

Estimated cost: $800-1,400

Typical onset: 100,000-140,000 mi

Symptoms: Excessive oil consumption (1 qt per 500-1,000 miles), Blue smoke on startup or deceleration, Loss of power, Low compression on one or more cylinders, Fouled spark plugs

Fix: Piston ring lands crack on the 6.1L, especially if engine has seen detonation or sustained high RPM. Requires complete teardown, new pistons and rings minimum, honing cylinders. Often discovered during valve seat repairs. 35-45 labor hours for full rebuild.

Estimated cost: $7,000-12,000

Typical onset: 80,000-120,000 mi

Symptoms: Clunking from rear on acceleration/deceleration, Vibration at highway speeds, Wandering rear end feel, Visible differential movement

Fix: The torque from the Hemi tears out the rear diff mounting bushings. Allows axle to shift under load, creating driveline vibrations. Replace all four diff bushings. 3-4 labor hours.

Estimated cost: $500-900