Postby smj999smj » Mon Aug 27, 2018 1:08 pm
2001 and later Pathfinders don't have timing belts; they have three timing chains. The VQ35DE has a lot more power and better gas mileage than the VG33E, but is a lot more technically advanced engine and has had more issues with check engine light issues. Some of the VQ35DE engines in the R50 Pathfinder had problems with the power valve screws falling out due to insufficient threadlock, allowing them to fall into the engine. Some have also had oil burning issues due to the oil control rings sticking in the lands and not being able to seal against the cylinder walls properly. Updated rings were developed later, but this requires tearing down the engine to replace them. Rusting at the bottom of the strut towers was an issue that was addressed in a recall. The automatic transmission is okay, but some experienced "shift flares" which were addressed by a service bulletin instructing to replace the shift solenoid pack.
Personally, I prefer the R51 over the R50, but they are not without their problems, especially the 05-06 model years. You have to be aware that there were a number of radiator failures that causes cross-contamination between the engine coolant and transmission fluid. There were also a number of VQ40DE engines that developed a whine from the upper timing chains due to a manufacturing flaw that require removal of the front timing cover and replacement of the upper timing chains and tensioner faces. On the plus side, they are otherwise a more reliable engine than the 3.5L and have more power. The transmission is better so long as it doesn't get contaminated. Gas mileage is a little better and the vehicle has a full frame, not a unibody.