One problem related to oil pump has been reported for the 2008 Jeep Grand Cherokee. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2008 Jeep Grand Cherokee based on all problems reported for the 2008 Grand Cherokee.
2008 Jeep Grand Cherokee limited 5. 7l hemi 4x4. Experiencing loud engine noise when first started. Most noticeable when engine is cold. More pronounced on colder days than warmer days. Appears to eventually subside after engine reached maximum operating temperature. Noise is not engine piston slap, does nopt increase when engine revolutions are increased, rather, it appears to subside, indicating valve train noise due to hydraulic lifter not fully pumping up, resulting in valve train chatter reminiscent of mechanical lifters needing adjustment, due to cold oil (higher viscosity) or low oil pump pressure. Changing to manufacturer recommended mobile1 seems to increase noise.