BMW M52B25 / M52TUB25 Engine

  1. Specifications
  2. Overview, problems
  3. Performance tuning

M52B25 / M52TUB25 Specs

Manufacturer  Munich Plant
Also called BMW M52
Production 1995-2001
Cylinder block alloy Nikasil-coated aluminum
Configuration Straight-6
Valvetrain DOHC
4 valves per cylinder
Piston stroke, mm (inch) 75 (2.95)
Cylinder bore, mm (inch) 84 (3.3)
Compression ratio 10.5
Displacement 2494 cc (152.2 cu in)
Power output 125 kW (170 HP) at 5,500 rpm
125 kW (170 HP) at 5,500 rpm (TU)
Torque output 245 Nm (181 lb·ft) at 3,950 rpm
245 Nm (181 lb·ft) at 3,500 rpm (TU)
Redline 6,500 rpm
HP per liter 68.2
Fuel type Gasoline
ECU Siemens MS41.0
Siemens MS42.0 (TU)
Weight, kg (lbs) ~165 (364)
~175 (386)
Fuel consumption, L/100 km (mpg)

for E36 323i
13 (18.1)
6.7 (35.1)

9 (26.1)
Turbocharger   Naturally aspirated
Oil consumption , L/1000 km
(qt. per miles)
up to 1.0
(1 qt. per 750 miles)
Recommended engine oil 0W-30
Engine oil capacity, L (qt.) 6.5 (6.9)
Oil change interval, km (miles)  7,000-10,000
Normal engine operating temperature, °C (F) ~95 (203)
Engine lifespan, km (miles)
-Official information

 ~250 (155)
Tuning, HP
-Max HP
-No life span loss


The engine is installed in BMW 323i E36
BMW 323i E46
BMW 523i E39

BMW M52B25 engine reliability, problems and repair

BMW M52B25 engine belongs to a new M52 series which also includes M52B20, M52B24, M52B28 and S52B32. It was firstly introduced in 1995 as an alternative to 2.5-liter M50B25 engine. The main difference between M52B25 and M52B28 is the fact that they have different crankshafts with lower stroke pistons and connecting rods.

At the same time M52B25 differs from M50B25 with its block of cylinders which were replaced with aluminum ones which are lighter in comparison with cast iron cylinders. At the same time connecting rods and pistons have also been replaced as well as intake manifold. Cylinder head was taken from M50 and from that moment variable valve timing system was used on all engines produced by BMW. 190 cc injerctors can also be found in new version of engine.

In 1998 several changes and upgrades have been made. The engine got its new name. It was called M52TUB25 where TU stands for Technical Update. Speaking about innovations and new features we should also mention cast iron sleeves in block of cylinders as well as second phase shifter on the Double-VANOS exhaust valve along with 244/228 duration camshafts, new pistons and connecting rods, intake manifold, renewed cooling system and electronic throttle body.

Due to the fact that new engine turned out to be less powerful in comparison with M50B25, it was mainly used in BMW autos with index 23i.

Starting from 2000 BMW M52B25 engine was pushed off by 2.5-liter 6-cylinder M54B25 motor and in 2001 production of those engines has been stopped.

BMW M52B25 engine modifications and differences

1. M52B25 (1995 – 1999) is a base modification of engine. Specifications are as follows: compression ratio – 10.5, power – 170 HP at 5,500 rpm, 245 Nm of torque at 3,950 rpm.

2. M52TUB25 (1998 – 2001) had renewed variable valve timing system. The engine got its second phase shifter and was called Double-VANOS. Cylinder block got additional craft iron sleeves which were installed on other camshafts. Specifications are as follows: compression ratio – 10.5, power – 170 HP at 5,500 rpm, 245 Nm of torque at 3,500 rpm.

BMW M52B25 disadvantages and problems

1. Overheating. As well as Series M50, M52 may have various problems including overheating. If you notice that motor is overheating, you should firstly check radiator and clean it in case of necessity. Also try to eliminate oxygen from the cooling system, examine pump, thermostat and radiator cap.

2. High level of motor oil consumption. The most common problem is the fact that piston ring wears out rather fast. This results in high level of oil consumption. The best way to prevent such problem is to change piston rings. If the problem still occurs you can also check crankcase gases ventilation valve.

3. Misfire. Problems with ignition can also occur rather often. It results in low productivity of cylinders which are disabled by ECU. Regular replacement of hydraulic lifters will be a perfect solution to this problem.

4. Oil light. If you face such problem you are supposed to check motor oil pump and oil filter housing.

At the same time camshaft and crankshaft position sensor can sometimes be out of order. You should also pay attention to such possible malfunctions and defects as unreliable thread for cylinder head bolts, thermostat flows, high demands on the quality of petrol (not for TU versions), lower average lifespan in comparison with its predecessor.

Moreover additional problems may occur while the engine grows older. This is a common disadvantage of the majority of BMW engines. This is why this version is not the best you can get. If you are planning to handle with Swap tuning, you are recommended to buy BMW M50B25 Non Vanos engine instead.

BMW M52B25 engine tuning

M52B25 Stroker. M50 Intake

The easiest way to increase the level of HP in BMW M52B25 engine is to purchase cold air intake system, M50B25 intake manifold along with camshafts of low duration 250/250 deg and lift about 10 mm. M52B28 injectors will also come in handy as well as light-weight flywheel and ECU chip tuning. All these action will make it possible to get 210-220 HP engine.

However there are several other ways which can increase capacity up to 2.8-liters. All you need is to install Stroker kit. You need to buy BMW M52B28 crankshaft using stock pistons. M52B28 ECU will be excellent choice for this purpose.

If you want your M52B25 2.8 Stroker show great performance, you need to purchase M50B25 intake manifold along with S52 camshafts and exhaust system or performance cat-back exhaust. When the tuning is completed, you will get maximum pleasure from your new engine. It will have up to 260 HP.

M52B25 Turbo

If you want to have turbocharged M52B25 engine, you should repeat the same actions that are described for M50B25. HERE you can get acquainted with detailed tips.