Nissan VQ25DE / Renault V4U

The Nissan VQ25DE is a 2.5 l (2,495 cc, 152.24 cu.in.) natural aspirated V6 60° 4-stroke gasoline engine from Nissan VQ-family. In Renault production line the VQ25DE engine is called V4U and used in the Renault Latitude and Renault Samsung SM5.

The VQ25DE (V4U) engine features a lightweight aluminum block with a fully balanced four-bearings crankshaft and two aluminum heads with two camshafts (DOHC) and four valves per cylinder. The Nissan VQ25DE engine is equipped with NISSAN EGI (ECCS) electrically controlled gasoline injection device and NDIS (Nissan Direct Ignition System) with individual coils on each spark plug. The later version has CVTC (Continuous Variable Valve Timing Control) system on intake valves.

There were two generations of VQ25DE:

• First generation (1994-2000): The first generation of the VQ25DE engine was used on the Nissan Cefiro, Cedric, Gloria and Leopard from 1994 to 1999 and on the Cefiro Wagon until to the middle of 2000. It produced 190 PS (140 kW, 188 HP) at 6,400 rpm and 235 Nm (23.9 kg⋅m, 173 lb⋅ft) at 4,000 rpm. In 1999 the VQ25DE was replaced by VQ25DD with direct fuel injection.
• Second generation (2004-present): In 2000, the production of the renewed version of the VQ25DE engine was resumed. This engine is equipped with CVTC (Continuous Variable Valve Timing Control) system on intake valves. This engine produced from 185 to 209 PS (136 to 154 kW, 182 to 206 HP) of horsepower and from 232 to 265 Nm (23.6 to 27.0 kg⋅m, 171 to 195 lb⋅ft)

Cylinder bore and piston stroke are 85.0 mm (3.35 in) and 73.3 mm (2.886 in), respectively. Compression ratio rating is 9.8 or 10.3:1.

The breakdown of the engine code is as follows:

• VQ – Engine Family
• 25 – 2.5 Liter Displacement
• D – DOHC (Dual Overhead Camshafts)
• E – Multi Point Fuel Injection

General information

Cylinder block

The VQ25DE-V4U has an aluminum cylinder block with a four-bearings crankshaft supported system, forged steel connecting rods, a micro-finished one-piece forged crankshaft. The crankshaft journal diameter is 60 mm (2.36 in), the crankpin diameter is 45 mm (1.78 in).

The cylinder bore is 85.0 mm (3.346 in), piston stroke is 73.3 mm (2.886 in) and compression ratio rating is 9.8-10.3:1. The Nissan VQ25DE motor has two compression and one oil control rings. The connecting rod’s length is 147.7 mm (5.81 in)

Main bearing cap bolts tightening procedure and torque specs:

• Step 1: 35.3 Nm; 3.6 kg·m; 26 ft·lb
• Step 2: Turn all bolts 90°

After securing bearing cap bolts, make sure crankshaft turns smoothly by hand.

Connecting rod bearing nut

• Step 1: 19.6 Nm; 2.0 kg·m; 14 ft·lb
• Step 2: Turn nuts 90°

Crankshaft pulley bolt

• Step 1: 44.1 Nm; 4.5 kg·m; 33 ft·lb
• Step 2: Put a paint mark on the crankshaft pulley
• Step 3: Again tighten by turning 60-65°, about the angle from one hexagon bolt head corner to another.

Drive plate fixing bolts

• 88 Nm; 9.0 kg·m; 65 ft·lb

Cylinder head

The cylinder head is made of strong, light aluminum alloy which gives it good cooling efficiency. The camshafts are driven by single primary and two secondary chains. The primary timing chain transmits the rotational movement from the crankshaft to the intake camshafts, the secondary chains connects intake and exhaust sprocket on each head respectively.

The intake valve diameter is 34.0 mm (1.34 in) and the exhaust valve diameter is 29.0 mm (1.14 in). The VQ25DE motor does not have hydraulic lifters, so special valve lifters are used to adjust the valve clearance.

Head tightening procedure and torque specs:

• Step 1: 98 Nm; 10.0 kg·m; 72 ft·lb
• Step 2: Loosen all bolts completely
• Step 3: 39.2 kg·m; 4.0 kg·m; 29 ft·lb
• Step 4: Turn all bolts 103°
• Step 5: Turn all bolts another 103°

Camshaft sprocket bolts

• Intake: 103 Nm; 11 kg·m; 76 ft·lb
• Exhaust: 123 Nm; 13 kg·m; 91 ft·lb

Problems and malfunctions

The Nissan VQ5DE is reliable and durable. The engine has three timing chains, their service life is about 150,000 miles of mileage (200,000-250,000 km). The valve clearance needs to be adjusted every 60,000 miles of mileage (90,000 km). The Nissan VQ25DE life expectancy is 200,000 miles of mileage (300,000 km).

Maintenance data

Valve clearance adjustment data

Calculate the thickness of new adjusting valve lifter so valve clearance comes within specified values.

R = Thickness of removed valve lifter
N = Thickness of new valve lifter
M = Measured valve clearance

Intake:
N = R + [M – 0.30 mm (0.012 in)]
Exhaust:
N = R + [M – 0.34 mm (0.013 in)]

Valve lifters are available in 27 sizes range from 7.88 mm (0.3102 in) to 8.40 mm (0.3307 in) for intake side and 6.66 mm (0.2622 in) to 7.18 mm (0.2827 in) for exhaust side, in steps of 0.01 (0.0004 in). The valve lifters are available with U or P stamp marks. (“P” for intake valves and “U” for exhaust). Install identification letter at the end, “P” and “U”, at each of proper positions.

Example (exhaust valve):
R = 6.80 mm
M = 0.52 mm
N = 6.80 + (0.52 – 0.34) = 6.98 mm, so we need a valve lifter with identification mark 698U.

Vehicle applications

Author: Sergei Wers
About: Co-founder and CEO of a multi-brand auto repair shop (engine repair, chassis repair, body repair and painting) for over 15 years. I have been developing internet sites with technical specifications for more than seven years.