The Unix Nerd's Domain
The BMW E23 Seven Series
The E23 was BMW's replacement for the big E3 2500-3.3Li saloons. It retained the good reputation for handling and performance set by such models as the 3.0Si. The E23 was launched in the UK in May 1977 and wasn't replaced by the E32 seven series until ten years later. During that time around 2000 were sold here compared to 30,000 overall, they were quite expensive when compared to Jaguars and other competitors.
The first cars were the 728, 730 and the 733i with it's advanced Bosch fuel injection. The 732i was sold from 1980-83 and was replaced by the 735i. The 728 an 730 were discontinued in 1979 and replaced for three years by the 728i.
In spring 1980 the range benefited from the addition of central locking, electric windows and tinted glass. The 735i gained headlamp wash/wipe.
In 1981 the five speed manual gearbox finally replaced the four speed unit as standard. In addition the BMW service indicator SI board appeared and ABS was available as an option.
In 1982 the four speed overdrive automatic gearbox was introduced as an option and there was a new front spoiler.
In the UK you could order a specially modified E23 estate version. This could even be combined with Alpina goodies!
The L7 was a very luxurious car for the time.
1982 UK spec E23.
Early German car with only one wing mirror.
Highly modified 735i in great condition.
All E23s were based on the M30 "big six" engine. All were 12 valve units except the South African version of the 735i. The 728 and 730 were the only non-injection engined models.
|Power / Weight
(bhp / 1000kg)
|Final drive ratio
|728i / iS||Saloon||M30||77-86
3.64 after 3/78
3.25 after 9/82
|735i||Saloon / Estate||M30||79-86||1500||139||3.25||Disc/Disc ABS*|
|745i turbo||Saloon||M102||79-86||?||?||3.07||Disc/Disc ABS|
|735i South Africa||Saloon||S38||?||?||?||3.07?||Disc/Disc ABS|
ABS was an option on early cars, not standard equipment. The above weights are mostly for UK spec cars. Automatic cars are 20kg heavier.
See the engine details page for power figures. US power figures for this car were quite a bit lower than euro figures and the cars were also heavier.
Early cars only had a 4 speed manual box or a three speed auto, later autos were 4 speed with overdrive.
The L7 was a luxury version only available in the US and in automatic form. This car had a leather head lining, leather door skins, leather dashboard, etc.
The South African 735i had a 277bhp engine taken from the M1 supercar.
The 745i was never officially imported to the USA.
Rust, be very afraid of rust. Look at inner wings, sunroof channels, rear suspension turrets.
Many E23s have TRX alloy wheels although early cars had 14" alloys. TRX's use a special size of tyre which is difficult to get and very expensive. Most owners fit 15 or 16" wheels to improve handling.
Electric seats can fail, especially headrests.
Pre 1980 engines have larger waterways in the cooling system than later models. This can sometimes cause the head to crack.
If the car overheats in traffic check the viscous fan coupling and the two speed electric fan (fitted to A/C equipped cars).
Check water hoses haven't perished, especially the smaller ones.
Check alternator bushes and mountings around 100,000 miles. Not hard to replace.
M30 engines can suffer from oil starvation on the camshaft resulting in damage. This is preventable with a new design of hollow bolt for the oil feed bar.
ZF 4 HP 22 automatic transmissions can fail due to a blown A clutch pack if revved strongly whilst in neutral or park.
Rubber engine mountings can perish, check engine isn't tilted forward and air flow meter is aligned properly.
Post 1982 models have a more reliable nylon "guibo" propshaft coupling insert.
Check differential mountings have not loosened and lowered the diff.
Worn rear subframe bushes can make car waver on the road.
Carefully check fuel lines and tank for corrosion. The tanks rust at the base of the filler pipe, only visible with a totally full tank of fuel.
Seized rear brakes are due to collapsed rear brake hoses.
Flashing ABS warning light often means that wheel sensors are rusting badly. Some owners disable the warning light so check it glows orange with the ignition on but the engine off.
Heating can stick fully on or off due to faulty heater control valve, not expensive to fix. Bad solder joints on the control unit or the two sensors can also cause problems.
If the fan works full on but not on variable speed then the transistor is dead. Test with the A/C on and off as there are two motors and controllers.
Check all the electrical goodies work, bits for these ain't cheap but they are generally reliable.
Best buying tip? Get a specialist to check it over and never assume rust is minor.