Removal and installation of a gear belt

6-cylinder M20 engines (320i, 325e), M21 (324d/td)

As part of the maintenance schedule, the toothed belt must be replaced every 4 years. If the toothed belt is removed, it must be replaced regardless of the service life.

Withdrawal

Set cylinder -1- to top dead center, see section «Removal and installation of the distributor of ignition».

Attention: On diesel engines, the position of the dead center of the cylinder -1- is indicated by a mark on the pulley. In this position, block the crankshaft with a pin (see section «Adjustment of the moment of the beginning of the supply of the high pressure fuel pump on a diesel engine»).

Loosen the engine front lifting eye.

Remove the alternator V-belt and deflect the tensioning bracket towards the alternator (see section «Removing and installing alternator V-belt. V-belt replacement»).

Petrol engines: Unbolt the power steering pump and, if fitted, the A/C compressor and lay them aside without disconnecting the connections.

Remove radiator (see section «Removal and installation of a radiator»).

Unscrew the belt pulley and vibration damper from the hub.



Remove vibration damper hub by unscrewing central bolt -H- with a 27 mm wrench. At the same time, use BMW special tool 112150 -G- to prevent the hub from turning.

Attention: To loosen the bolt, a high tightening torque must be overcome (400 nm).

Remove lug washer -K- and tighten bolt again by approx. 3 turns.

Pull the hub off the crankshaft using a suitable puller. resting the axis of the puller in the head of the bolt. After that you return the bolt and remove the hub.

Petrol engines: Release the TDC sensor cable from its mounting on the toothed belt guard. Pull out the top dead center sensor.

Diesel engines: unscrew the cylinder head cover.

Unscrew the toothed belt guard and pull it up.



Loosen bolts -E- and -F- and press tensioning roller -R- inwards with a screwdriver -S-.

Tighten bolt -E-.

Remove toothed belt.

Attention: When the toothed belt is removed, do not turn the engine if possible, as serious damage to the pistons and valves can occur -

Installation, gasoline engines

Attention: When applying a toothed belt, the position of neither the camshaft, the intermediate shaft, nor the crankshaft must be changed. Otherwise, severe engine damage may occur or the engine will not develop full power.

After tensioning the toothed belt again, check the installation of the camshaft and crankshaft.



Fit new toothed belt, starting with toothed pulley -1- on crankshaft. Then place the toothed belt -2- on the pulleys in numerical order in the illustration.

Tension

Remove all spark plugs.

Attention: With the spark plugs turned out, the engine can only be turned using the adapter on the camshaft sprocket.

Loosen bolts -E- and -F- and turn engine at camshaft sprocket adapter -N- in the opposite direction to engine rotation. In this case, the toothed belt is tensioned by a tension spring. Finally tighten bolts -E- and -F- to 22 Nm.

Caution: If turning the camshaft sprocket loosens the bolt, tighten the bolt to 70 Nm.

Turn the engine 1 revolution in the direction of engine rotation until the mark on the camshaft pulley -N- aligns with the mark on the cylinder head (arrows). At the same time, the mark on the crankshaft flange -K- must also coincide with the protrusion on the cover.



Otherwise, remove the toothed belt again, align the pulleys according to the markings and re-apply and tighten the toothed belt.

Installation, diesel engine

Fix the camshaft using the BMW tool at the top dead center of the 1st cylinder, for which there is a platform on the shaft near the cam of this cylinder. If necessary, make the device yourself. With a new toothed belt or with a vehicle mileage of less than 15,000 km, a 2.5 mm thick gasket must be placed on the side of the exhaust valves of the cylinder head.


Loosen the camshaft sprocket bolt. The camshaft sprocket must be able to rotate relative to the camshaft.



Insert a BMW rod or a suitable homemade rod into the console through the hole in the toothed pulley of the high pressure fuel pump. The rod fixes the gear pulley of the high pressure fuel pump in the position of the top dead center of the 1st cylinder.

Install toothed belt when engine is cold (room temperature, 15-35°С), starting from the toothed pulley -1-crankshaft. Then fit toothed belt -Z- according to numbering in figure W-1041.

Turn the tensioning roller at the bolt -F- (pic. W-1042) to the right with a torque wrench. Belt tension torque with mileage up to 15,000 km: 45 nm, over 15,000 km: 35 nm.

In this position, tighten the tension roller.

Tighten the camshaft sprocket bolt to 70 Nm.

Attention: Remove the fixing pins of the high pressure fuel pump sprocket and crankshaft. Remove the camshaft retainer.

Install the cylinder head cover by evenly tightening the bolts. Replace damaged gasket.

Remove the protective cover, insert the top dead center sensor and fix the wire of the top dead center sensor on the bracket.

Install the vibration damper hub. Install the bolt with a tidal washer and tighten it to a torque of 410 Nm.

Screw on vibration damper pulley.

Install radiator (see section «Removal and installation of a radiator»).

Screw on the power steering pump and. if removed, the air conditioning compressor. Tension the V-belt (see section «Replacing and tensioning the V-belt of the power steering pump»).

Insert toothed belt guard.

Install and tension alternator V-belt (see section «Removing and installing alternator V-belt. V-belt replacement»).

Screw on the front lifting eye and engine bracket.

Diesel engines: adjust the timing of the start of fuel injection (see section «Adjustment of the moment of the beginning of giving of the fuel pump of a high pressure on the diesel engine»).