Checking and Correcting Installed Length of Valve Springs

5 nee it is hardly possible to check the installed length of valve springs with workshop equipment, s is recommended to measure as shown in the picture.

— Install valve and hold in valve seat.

— Valve stem end must have specified distance to level bearing surface in cylinder head: 39.7 + 0.5 mm for intake valve or 38.7 + 0.5 mm for exhaust valve.

If end of valve stem is not within tolerances, the installed length for valve springs can be corrected with 0.5 mm thick shims (A).

Cylinder Head Cover Installing

The washers between the cylinder head cover and bolt heads have rubber liners (arrows). This guarantees that all washers have an "elastic" tight fit, since the bolts bear on collar (A) and do not clamp down on the washers.

Oil Dipstick and Guide Tube

(All Engines)

The oil dipstick and corresponding guide tube are changed because of the 8.5 mm higher toothed belt tensioner.

At the same time the oil dipstick and guide tube are approx. 100 mm longer.

This makes checking the oil level considerably easier.

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Water Pump

(All Engines)

The rotating components of the water pump are stronger and made of better materials.

Throttle Housing

(Engines M 28/21 and 22)

The gate between the opening lever and throttle valve shaft is that of 32-valve engines.

- Softer pick-up while accelerating.

- Better fuel metering.

Control Units for Engines with Four Valves Per Cylinder

The lower compressed engines M 28/45 and 46 have the following control units. LH control unit 928.618.123.04 EZF control unit 928.618.124.06

These units are adapted to the low octane number and engine compression.

B) Engines M 28/43 and 44 (US Engines)

The higher compressed engines are equipped with the following control units. LH control unit 928.618.123.04 EZF control unit 928.618.124.05

Engines in Cars Exported to Sweden and Switzerland

(Engines M 28/21 and 22)

Switzerland and Sweden have stricter legislation on emission control for 1986. Consequently the engines M 28/21 and 22 in cars for export to these countries have pistons which produce a compression ratio of 9.3 to 1 (10.4 to 1 compression ratio worldwide).

The pistons have a central bowl (arrow) in addition to both valve pockets.

The ignition performance curve is also changed with an adapted ignition control

Idle: 5° before TDC

(worldwide 10° before TDC)

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