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Discussion Starter #1
Any Infinty techs here? I am working on a 2017 Pathfinder 3.5 VQ35DD (same as QX60). Upon engine disassembly, I realized the Gear that turns the bottom mounted oil pump is only held in place on the crankshaft by the torque of the main pulley bolt, against the timing gear, then against the oil pump gear. No keyway, no pins etc. Can this possibly be right? 2 smooth surfaces pressed together with a bolt to turn a gear? Meaning if the bolt was the least bit loose, the oil pump would not turn. I can find no info on this, the parts diagrams do not even show that gear or chain that drives the oil pump. I am new to this Direct injected engine and I am perplexed. Thank you for any info.
 

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Is there 2 large flats on the pump that engage the same 2 flats on drive spacer, axial to the crankshaft?
 

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Discussion Starter #3
No sir. The oil pump is mounted on the bottom of the block, inline with the main bearing caps. It is chain driven, with a short chain by a sprocket behind the timing gear on the crankshaft snout. The timing gear is keyed to the crankshaft, but the oil pump gear spins freely until the balancer bolt is tightened. I assembled it that way and torqued the bolt to specs. I realize the oil pump requires little force to spin, but I still found it odd that the gear was not keyed to the crank.
 

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The logic of the system is - perhaps - that if the oil pump was to become siezed by some piece of metal debris, it would not damage the crank. In this scenario, the lack of oil pressure would trigger a CEL and emergency warning message to shut off engine.
 
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