YD25 Oil Pump Gear Failures

Oil Pump Gear Failures

We have found during the installation of several hundred YD25 duplex timing chain conversion kits that on some YD25 engines the inner oil pump gear is wearing excessively on the drive contact faces. The harmonic balancer oil pump drive faces can also show signs of wear. About 1 in 5 of the engines were affected by this excessive wear to the oil pump gear. We have had reports from the motor trade that some YD25 vehicles have turned up in workshops with the oil pressure light flashing. Further investigation revealed that the oil drive faces were worn away. The original Nissan YD engine oil pump gears are manufactured using the Powder Metallurgy Sintered Metal process.  This is a widely used process which helps manufacturers keeps costs down. However occassionally it can result in inconsistent metal density which leads to rapid gear wear. See examples below.

 yd25 oil pump worn gear 1      yd25 oil pump worn gear 2 
 Oil pump failure    Oil pump failure