Common E21
problems
- Water leaking in the front (i.e. glovebox) is often caused by a
worn windscreen rubber, replace with new & original one
- The rubber valve seals wear out quite easily, especially after over
20 years of service - replace and prevent this for example by keeping the
revs down when the engine is cold. And if the temperature gauge has
arrived in the middle the coolant is at the right temp. Oil and metal need
much more time to reach ideal operating temperature!!!
- After removing the cylinder head, never re-use the old head bolts
as they can break, always replace them
- Overheating or noisiness can be signs if a broken cooling fan
clutch (should blow strongly only when the engine is hot)
- An extremely high stationary rev count is usually caused by a dirty
or worn auxiliary air valve or worn air hoses connected to it (fuel
injection only). The fuel injected E21s can also have trouble starting,
combined with a rough cold idle. Most times the warm up regulator is to
blame.
- Jumpy fuel and temperature meters are often caused by loose
grounding. Start at the back of the instrument cluster and check
connections and ground nuts
- Oil pressure transmitters often do leak, as do oil seals on gearbox
and diff, and the oil pan gasket. And don't forget to replace the rubber
half moons under the valve cover. As they tend to be forgotten when the
valve cover gasket is replaced, leaks on top mostly come from here (Half
moons only in M20 engine (320/6, 323i): when you remove the valve cover
gasket, on both ends of the head there are 2 half moon cutouts that have
rubber plugs in them. people sometimes don't change them and when they
leak it looks as if the head is leaking. You don't have to replace them every
time but chances are the current ones are 10-20 years old. The part no is
11 33 1 264 519. Changing them is easy).
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