Engine BMW S38B36

Especially for the BMW M5 E34 released in 1988, a new sports engine called the S38B36 was designed. The basis for this engine was the aspirated M88/3 (S38B35), with a colleague in the series, M30B34, S38 has less in common.

A lightweight forged crankshaft with a piston stroke of 86 mm (was 84 mm) and 12 counterweights was installed in the M88/3 cylinder block. The cylinder diameter remained unchanged (93.4 mm), the pistons were modified, their compression height was 31.5 mm, and the compression ratio was 10, the length of the connecting rods was 144 mm.

The cylinder head of the BMW S38 is a two-shaft 24-valve with mechanical pushers. Valve adjustment is carried out as necessary, cold clearances 0.28 / 0.33 mm. Camshaft parameters S38B36: phase 264/110, lift 10.7 mm. Intake valves are 37mm, exhaust 32mm. The intake has a variable geometry manifold and, of course, 6 throttles, one for each cylinder, the diameter of each throttle is 46 mm. The nozzles have a capacity of 270 cc.

Control unit – Bosch Motronic M1.2. At the outlet, an equal-length collector is used. The timing drive uses a double-row chain, which is quite reliable.

These innovations made it possible to remove the power of 316 hp at 6900 rpm.

S38 family: S38B36, S38B38.

Specifications

Production years	1988-1996
Displacement, cc	3535
Fuel system	injector
Power output, hp	316 /6900 rpm
Torque output, Nm	360 /4750 rpm
Cylinder block	cast iron R6
Block head	aluminum 24v
Cylinder bore, mm	93.4
Piston stroke, mm	86
Compression ratio	10.0
Hydraulic lifters	no
Timing drive	chain
Turbocharging	no
Recommended engine oil	5W-30 / 5W-40 / 10W-40 / 15W-40
Engine oil capacity, liter	5.75
Fuel type	petrol
Fuel consumption, L/100 km — city — highway — combined	18.0 8.3 9.6
Engine lifespan, km	~400 000
Weight, kg	~151
Oil consumption, gr/1000 km	up to 1000

The engine was installed on:

• BMW M5-Series E34 in 1988 – 1993.

Disadvantages of the S38B36 engine

The main problems of the BMW S38 engine are cracks in the cylinder block, overheating. Cracks form around the threads for the cylinder head bolts. The reasons for the breakdown are oil that has not been removed from the thread, disassembly of the motor. The problem can be diagnosed by the high consumption of antifreeze, the appearance of an emulsion in the oil. The optimal solution is to replace it with a non-cracked block.

If overheating occurs, the problem must be solved quickly so that the cylinder head does not move. Overheating occurs when a thermostat, radiator or pump needs cleaning, or when there is a blockage in the cooling system.

Frequent malfunctions include wear of the elements of the gas distribution system, the complexity and inability to adjust the valve. To solve the problem, eccentrics, guide bushings and valves are changed. Poor performance may be related to the MAF. During the warming up of the car, a whistle is heard, there are frequent leaks of the rear crankshaft oil seal.

Frequently asked questions about the BMW S38B36