BMW 3: Chain drive - Crankshaft drive
Features:
- Chain drive at the side of the engine emitting the forces.
- Single-part chain drive for driving the camshafts.
- Single sleeve-type chain 8 mm.
- Electric motor of the combined oil-vacuum pump via a separate chain.
- Plastic tensioning and guide rail.
- Hydraulic chain tensioner with spring preload and sealing sleeve.
The following comparison shows the differences between the timing chain drive
of the B46 engine
and that of the B46TU and B48TU engine:
Comparison chain drive B46 engine with B46TU
- Two-part chain drive B46 engine
- Single-part chain drive B46TU and B48TU engine
- Slide rail
- Top timing chain
- Chain tensioner
- Tensioning rail
- Bottom timing chain
- Camshaft sprocket, oil/vacuum pump
- Drive chain oil/vacuum pump
- Guide rail
- Timing chain
The main difference between the chain drive compared with the B46 engine is
the move from a two-
part timing chain drive to a single-part timing chain drive. The timing chain
direly drives the camshaft
sprockets on the camshafts. Deflection via the intermediate shaft on the top
timing chain and the
second timing chain is no longer needed. The chains used here are 8 mm
sleeve-type chains. Because
the intermediate gearing is no longer needed, the number of teeth on the
crankshaft (23 teeth) and the
VANOS unit (46 teeth) has also changed.
Comparison chain track, B38 and B38TU engines shown
- Chain track two-part timing chain drive (B38 engine shown, B46 is
identical)
- Chain track single-part timing chain drive (B38TU engine shown, B46TU
and
B48TU are identical)
- B38 & B38TU engines shown
- Upper timing chain
- Timing chain
- Lower timing chain
- Drive chain oil/vacuum pump
The way the combined oil/vacuum pump is driven by a separate drive chain from
the crankshaft has
not changed. Only the renewal of the chain tracks has changed; the drive chain
for the oil/vacuum
pump is now located in front of the timing chain.
Eliminating the second timing chain offers the following benefits:
- Improved acoustics
- Lower space requirement
- Reduced weight
READ NEXT:
Chain tensioner
Tensioning rail
Sealing sleeve
Chain tensioner with screw thread
Due to the cylinder head manufacturing process, the chain tensioner now has a
sealing sleeve with a
height of 12
VANOS
VANOS unit B46 engine and B46TU/B48TU engines
VANOS B46 engine
VANOS B46TU and B48TU engine
Following the changeover from a two-part chain drive to a single-part chain
drive, the camshaft
Comparison belt drive B46 engine and B46TU/B48TU engines
B46 Engine (transverse installation shown)
B46TU/B48TU engines (transverse installation shown)
Deflecting element
Alternator
Coolant p
SEE MORE:
Your car is equipped with a wireless charging
tray (WCA) to charge your mobile phone and
connect it to the mobile network. To ensure the
best possible connection a signal booster (LTECompensator)
is used in conjunction with the
WCA. The following paragraphs refer to this
booster:
This is a CONSUMER
General information
Depending on the national-market version, the
destinations are automatically stored as received
destination and can be applied in the destination
guidance, if they were transferred to the vehicle
via the BMW Connected app.
For example, destinations that were sent from
the Concie