The BMW M52B25 engine from the M52 family (it also included the M52B20, M52B24, M52B28, S52B32) was introduced in 1995 and was positioned as a replacement for the 2.5-liter M50 representative. The geometry of the bottom remained the same, but the cast-iron block was replaced with a lightweight aluminum cylinder with a Nikasil coating, pistons and connecting rods changed.
M52B25 connecting rod length – 140 mm, piston compression height – 32.55 mm. A different intake system was applied. The cylinder head has moved from the M50 Vanos and now the variable valve timing system is used on all engines. Injectors on M52B25 – 190 cc.
In 1998, the motor underwent some modifications and was named M52TUB25 (Technical update). Among the innovations are the appearance of cast-iron liners in the cylinder block and the second phase shifter on the exhaust shaft (Double-VANOS), other camshafts 244/228 lift 9/9 mm, pistons and connecting rods, a new DISA intake manifold, a modified cooling system, electronic throttle.
Due to the fact that this power unit turned out to be more torquey and not as powerful as the M50B25, it was used on BMW cars with the 23i index.
Specifications
| Production years | 1995-2001 Munich Plant |
| Displacement, cc | 2494 |
| Fuel system | injector |
| Power output, hp | 170 |
| Torque output, Nm | 245 |
| Cylinder block | aluminum R6 |
| Block head | aluminum 24v |
| Cylinder bore, mm | 84 |
| Piston stroke, mm | 75 |
| Compression ratio | 10.5 |
| Features | no |
| Hydraulic lifters | yes |
| Timing drive | chain |
| Phase regulator | single VANOS (M52B25) double VANOS (M52B25TU) |
| Turbocharging | no |
| Recommended engine oil | 5W-30 |
| Engine oil capacity, liter | 6.5 |
| Fuel type | 95 |
| Euro standards | EURO 2 (M52B25) EURO 3 (M52B25TU) |
| Fuel consumption, L/100 km (for E36 323i) — city — highway — combined |
13.0 6.7 9.0 |
| Engine lifespan, km | ~350 000 |
| Weight, kg | ~165 (M52B25) ~175 (M52B25TU) |
Disadvantages of the M52B25 engine
- The first years used nikasil coating of cylinders and it quickly collapsed;
- The engine is very afraid of overheating, the cylinder head immediately leads from it and breaks through its gasket;
- The cause of frequent misfires is usually coked hydraulic lifters;
- DISA variable geometry damper can break loose and fall into cylinders;
- Another weak point is the crankcase ventilation valve membrane;
- After 100,000 km of run, the Vanos phase control system often needs to be repaired;
- On a run of 200,000 km, an oil burn often begins due to stuck piston rings.
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