Design and Function

Design and function

Engine block










Cylinder head, camshaft bearing housing









The cylinder head is of the cross-flow type, (Cross-flow = in from one side and out from the other side).
The two camshafts are supported by seven bearing caps each, directly in the cylinder head and camshaft cover. The camshaft cover works like a combined valve cover and camshaft bearing cap. The camshaft cover has cast oil ducts on the underneath which ensure good oil supply to the camshafts and the valve lifters.
The maintenance-free valve lifters, valve springs and valves are in the cylinder head.

Cylinder head gasket




The seal between the cylinder head and cylinder block is a conventional cylinder head gasket. The seal between the other gasket faces is a liquid gasket.
The cylinder head gasket is made of steel and has multiple layers.
For exact adaptation to the relevant piston height there are different thicknesses available. This is to absorb the differences between pistons, connecting rods etc and thereby obtain the correct compression.

Cylinder block




The cylinder block consists of 3 sections.
- Cylinder block
- Intermediate section
- Gear housing
All three sections are made of die cast aluminum, molded under high pressure.
The mating flange between the cylinder block and intermediate section is in the center line of the crankshaft. The gear housing for the camshaft drive is secured on top of the cylinder block.
The cylinder block houses six cast iron cylinder sleeves. These cylinder sleeves cannot be replaced. The stroke length of the cylinders is greater than the cylinder diameter. This produces good torque and competitive power.
The intermediate section's seven main bearing caps have cast iron reinforcements.
On the top of the intermediate section there are cast oil channels which distribute the oil to the main bearings and on via the crankshaft to the big ends.

Oil pan




The oil pan is made of die cast aluminum with baffles. This is so that the oil does not splash excessively. Liquid gasket creates a seal between the cylinder block and the oil sump.
The oil pan is designed to reduce mechanical noise from the engine, at the same time as providing a reliable supply of oil at different angles. A composite oil scraper keeps the larger section of the oil volume away from the rotating crankshaft. It minimizes power loss, improves fuel economy and prevents the oil from foaming.
The oil suction line, which runs from the oil pan, is made of plastic. The oil pan is equipped with an oil level sensor.
The oil pan contributes to the rigid design and operates as an extra reinforcement of the cylinder block.

Piston




1. Piston cooling nozzle
The pistons are die cast in aluminum and the connecting rods are forged in steel.
The heat received by the pistons from combustion, is cooled, partly via the coolant jacket in the block but also by the oil from the six piston cooling nozzles.

Crank system









The crankshaft is made from forged steel with induction hardened bearing surfaces.
The sprocket is crimped on the crankshaft's rear most shank.
The crankshaft is supported by seven main bearings. The main bearings are replaceable main bearing shells. The sixth main bearing is a thrust bearing that holds the crankshaft in a determined position along the length of the axle.
An internal vibration damper is on the front end of the crankshaft. Inside the enclosed vibration damper, a circular flywheel works on a silicone fluid, which dampens the crankshaft torsion oscillations. The vibration damper gives longer service life for the crankshaft and smoother engine operation.
The energy that is generated in the vibration damper, is converted to heat, therefore, the unit is cooled with oil via the oil cooler pipe.

Intermediate shaft









The intermediate shaft is located in the gear housing on the cylinder block. The intermediate shaft drives the camshafts and the auxiliary unit.
There is a sprocket on the rear section of the crankshaft, which drives the intermediate shaft via an intermediate wheel. The intermediate wheel drives the intermediate shaft via the intermediate shaft's centrally mounted gear. The intermediate shaft has a further two gear wheels of different sizes.
The intermediate shaft's front gear wheel has a freewheel clutch that drives the alternator at 2.7 times the engine speed. A free wheel clutch drives in one direction and slips/freewheels in the other direction.
The rear gear wheel drives the overhead camshafts.

Camshaft transmission









Both camshafts are driven by a camshaft chain, which in turn, is driven by the crankshaft via the intermediate shaft. The camshaft chain has inverted teeth, so called, "silent chain".
The chain drive is maintenance free.
The exhaust side's camshaft has a vibration damper, which guarantees optimum balance in the gear and chain sprockets.

Timing cover









The timing cover is cast in aluminum.
The coolant pump shell is integrated in the timing cover. This saves weight. The coolant pump is still driven by the auxiliary unit's transmission.
The chain us tensioned by a hydraulic chain tensioner, which is located in the timing cover. Oil injection pipes supply the chain with oil.

Variable camshaft profile (CPS), only applies to B6324S









The ideal engine should have low valve lift for low engine rpms and loads, and high valve lift at high rpms and loads.
To achieve this, an engine with two completely different camshaft profiles is required.
This engine has a patented system for camshaft profile switching. The system uses two completely different cam profiles designed on the same camshaft.
The inlet camshaft is provided with three cams for each valve, one centrally located with small lift height, 3.6 mm, and two equally sized outer cams with big lift height, 10.0 mm. With a small lift height at low load and at engine speeds up to approx. 3000 rpm, the primary benefit is lower fuel consumption.
In principle, during the time that the lift height is small, the air damper is completely open. Control of the incoming air volume to the cylinders takes place through control of the camshaft's opening times. Hereby the pump losses are reduced, which in turn gives lower fuel consumption. For more information, see Design and function, Engine control module (ECM).

Low lift
At small lift height (4), only the centrally placed cam acts on the valve, which takes place trough the inner valve depressor. The outer cams act on the outer valve depressors, which follow the cams' movement. Since the centrally located valve depressor and the outer depressor are not connected, the outer depressor moves without affecting the valve. Thus, lift height becomes small.

High lift
At high lift height (3), the inner valve depressor is connected with the outer valve depressor with lock pins. The outer camshaft cams' movement is transmitted through the outer valve depressor, on through the lock pins and the inner valve depressor to the valve. Thus, lift height becomes big.
The position of the lock pins is controlled hydraulically with two electro-hydraulic valves. One electro-hydraulic valve controls the valves for cylinders 1, 2 and 4, while the other controls the valve for cylinders 3, 5 and 6. Thus, the electro-hydraulic valves control 6 valves each (as the engine has 2 inlet valves and 2 exhaust valves per cylinder).
The position, on/off, of the electro-hydraulic valves is controlled by the Engine control module (ECM). For more information, see Design and function, Engine control module (ECM).
The inner valve depressor works like a hydraulic valve depressor, which compensates any wear. Thus the valve clearance is "0".
The exhaust camshaft is conventional and has a lift height of 10.0 mm. The valve depressors are mechanical, that is, they "have" valve clearance.

Lubrication system









The task of the lubrication system is to build-up a protective film of oil between the moving parts of the engine. The lubrication system must also transport dirt particles away from the moving parts and cool hot engine parts.
This is carried out by the oil pump supplying oil to the oil filter through an oil pressure line of treated steel.
Clean oil is supplied to the oil cooler from the oil filter to the oil cooler. From there the oil is further distributed, through a duct system, out to the various engine functions.
A pressure sensitive valve controls the oil flow to the vibration damper's oil cooler pipe if necessary.

Oil pump




The oil pump is in the oil pan, mounted underneath the intermediate section. The oil pump has an integrated relief valve. The pump is directly driven by the sprocket on the rear end of the crankshaft.
The oil pump draws oil from a centrally located nozzle in the sump.
The pump increases the pressure of the oil for lubrication, cooling and hydraulic functions.

Oil filter module




The oil filter module consists of an oil filter reservoir and an oil cooler. It is mounted on the intermediate section. The oil filter module is element based and can be taken apart.
The oil cooler is connected to the coolant system. Coolant is led through the oil cooler.

Cooling system




The coolant pump shell is integrated in the timing cover. The pump wheel is still driven by the auxiliary unit's transmission.
The coolant pump pumps coolant through the cylinder block, and also cools the cylinder head, cylinder sleeves, spark plug wells, intake ducts and fuel injection nozzles.
The coolant flows in at the coolant pump and passes through a number of channels before it collects and then flows out to the thermostat housing. If the thermostat housing is closed, the coolant passes via the by-pass channel directly to the coolant pump to then circulate through the cylinder block again.
For the turbocharged engine, the task of the cooling system is to supply the turbocharger with coolant.

Crankcase ventilation




The crankcase ventilation is maintained internally in the engine.
An oil separator is on top of the engine's camshaft cover. It separates the oil drops from the air in the crankcase. The drops are collected in a separator and flow back inside the engine to the oil pan. This prevents extra weight and space for external pipes.

Auxiliary unit transmission









The auxiliary units are located at the upper edge of the cylinder block, above the transmission. They are driven by two systems, a Poly-V-belt driven system and a clutch system. These two systems are driven by the intermediate shaft transmission.
The belt system consists of a 6-ribbed Poly-V belt, an automatic belt tensioner and a guide pulley. This system drives the servo pump and AC compressor. The coolant pump is driven by the servo pump via the clutch system.

Turbocharger (TC)

Note! Only applies to turbocharged engines.




The exhaust gases enter via the manifold (1) down to the turbine housing (8) and out to the exhaust system via a downpipe and catalytic converter.
The turbine expels the exhaust gases and rotates the compressor wheel (3). The compressor wheel creates a certain amount of suction using the intake air. This intake air enters the compressor via the air filter and uses a rotational movement to speed up the air, creating the boost pressure. The air then continues into the intake system via the charge air pipe and charge air cooler.
The electronically controlled By-pass valve (4) then controls the boost pressure in the turbocharger by determining the amount of exhaust gases which must pass the turbine. The turbine transfers drive to the compressor. The wastegate valve (2) is a membrane which equalizes the pressure of the intake and exhaust air to eliminate noise.
The turbocharger is lubricated by the engine's oil system (7). The oil system also acts as a supplement to the coolant system (5 and 6).