The following table provides a quick overlook of the main engine types used in BXs:
It usually dies either when you (try to) start the engine or when you stop it, rarely while it's running. The engine will not start because it will not be getting any fuel. The reason is usually overheating and deformations in the coil whichresult in the valve plunger getting stuck, or internal shorts or open circuits (due to heat) in the coil.
Clean combustion resulting in clean oil (assuming it has the proper grade, not some cheap concoction) is essential not only for the engine but for the turbo as well. Most people are not aware that a turbo can be--and actually should be--cleaned every 150,000 km or so. This procedure will make it last forever.
This is a typical problem with CAV DPS/DPC fuel pumps. The fuel leaks along the edge of the solenoid housing (a round part with a huge nut on its housing, screwed into the side of the pump). Remove it by unscrewing it with the appropriate wrench, having unplugged the electrics first, of course. The leak develops where the back of the solenoid is joined with the rest of the body, and the replacement is very expensive (cca 160 Euros).
There were the wrong type of engine supports fitted to early diesel XMs, supposedly up to Q1 of 1992). The replacement top ones are softer and taller, and have a different shape. In fact, the original ones made the engine sit at an angle (the gearbox end was higher by about 1/3 of an inch). Post-1993 microfiches show this replacement, pre-1993 ones do not.
Steam and water cleaning older engines with fuel injection is always a little bit risky. Humidity getting into some parts can make re-starting a challenge. Note that we don't speak of permanent damage, only that you'll have to wait or dry those parts with compressed air. If you do this yourself, there's no problem, but at a garage, when other cars queue up behind you, it can be bothersome.
All gasoline engines are four-cylinder, aluminum alloy, in-line, overhead camshaft, water cooled engines mounted transversely. The engine type can be found on the engine number and manufacturer's plates.
1124 ccm gasoline engines
A few models exported to Italy and Greece were fitted with engines normally used only in the AX.