140 kw engine

YD25 duplex timming chain conversion genuine kit

The original euro 2 yd25 engine had a double row fuel pump chain. The euro 3 and euro 4 yd25 engine used a single row fuel pump chain but the guides and sprockets remained double row thickness. The euro 5 140kw engine still uses a single row chain but the sprockets were made thinner.

sprockets comparison


Because the sprockets are thinner on the 140kw model when you put a double row sprocket on the crank it pushes out the crank helical gear reducing the contact area between the balance shaft gears. Some parts suppliers have made a 1/2 thickness crankshaft helical gear to drive the balance shaft idler gear. Having 1/2 the gear meshing area than the original. This causes the idler gear to wear excessively. The shed metal contaminates the engine oil causing damage to the oil pump first then the rest of the engine. 

140KW simplex chain original idler   140KW duplex chain original idler   140KW duplex chain original idler2
 140kw single row chain balance shaft gear alignment    140kw with duplex chain fitted misaligned crank gear    140kw with duplex chain fitted misaligned crank gear


Due to the balance shaft gear misalignment, there are 2 options either don't run the balance shaft which Nissan does with all yd25 d22 Navaras, and single cab 2wd d40 Navara or maintain the balance shaft by make a thicker balance shaft idler gear to retain the full thickness of the balance shaft gears.

Balance shaft delete 140kw with balance shaft
 Balance shaft delete with a spacer in place of the crank helical gear  Balance shaft retained with billet helical gears


140 Kw engines come with 2 vacuum pumps. We cannot tell from the VIN which pump is fitted.  You need to identify which pump is fitted to your car. Below are the 2 pumps. The sprockets for each is different. It is imperative that sprocket chain alignment from the crank to vacuum pump is achieved. This is done by us making special shims. Check chain alignment from the vacuum pump sprocket to the fuel pump sprocket is a must for chain longevity. This is achieved with fuel pump shims.

Yd25 early vac pump   Yd25 late vac pump
Early vacuum pump    Late vacuum pump