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Common issue with the yd25 engine is that the oil pump gears wear on the drive flats. The oil pump gears are sintered (powder metal heated and compacted in a mold) This is a widely used process that helps manufacturers keep costs down. However, it can result in inconsistent metal density which leads to rapid gear wear. See examples below.

New Oil Pump Drive Flat	Worn Oil Pump Drive Flat

 

Sintered materials are prone to shattering. If the gears are hit when reinstalling the harmonic balancer pulley it can break the gears. Aggressive rev limiters and crank walk-in high-performance engines also put a lot of stress on the oil pump leading to shattered oil pump gears. 

Sintered Cast Gears Shattered Into Multiple Pieces

 

To fix the issues we have developed billet 4140 oil pump gears. We make 2 types of billet oil pumps, the first type is slightly wider than the OEM, maintaining the single shoulder design on the inner gear. For high-performance engines, we made a double shoulder design this gives the maximum contact area between the oil pump drive and harmonic balancer.

	Billet 4140 Oil Pump Gear Set	OEM Inner Gear Width	Billet Single Shoulder Width	Billet Double Shoulder Width

 

Our oil pump gears are fitted to new oil pump housings. Our oil pumps come complete with the oil sprayer fitted.  Oil pumps from Nissan do not include the sprayer and is sold as a separate part. If the oil pump is fitted without a sprayer, there will be enough oil pressure for the light on the dash to go out, but not enough for the turbo, resulting in a blown turbo. We also shorten the alignment dowel to reduce the chances of cutting the black O-ring when installing the oil pump with the sump in place. Oil pumps from Nissan also dont come with oil or grease on the gears. We prelube the gears with grease to prevent damage and ensure oil pressure comes up as soon as possible on first startup. The OEM oil pumps have no thread sealant on the oil pump backing plate screws. To prevent these screws from coming loose we apply a small amount on them when assembling. 

Oil Sprayer Location	Oil Sprayer

 

D40 R51 HARMONIC BALANCERS

Before replacing your oil pump check the harmonic balancer pulley. On a D40 the harmonic balancer drives the oil pump and can wear like the oil pump gears. If your D40 harmonic balancer pulley needs replacing, we stock brand new pulleys Click Here

Worn D40 Harmonic Balancer Pulley

 Watch our install video