E24 Six Series


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//M Car



BMW E24 Six Series Problems & Buyers Guide

Body & Fittings

Sixes are very well made cars but even the youngest is now 26 years old. They rust, but it's not fatal. The biggest problem is the front wings. They have no inner splash guard except at the back (20 quid each and I'll bet yours need replacing) and this causes both the inner and outer wings to rust. They cost about 650 quid each but all sixes will need a set at some point.

Another common rust spot is the front of the footwells. These get all the splashback from the wheels and it shows. Ensure yours are well undercoated if they're still OK.

The rear shock towers are a common weak spot in old BMWs but the Six isn't as bad as the 2002, worth a check though. I'd also remove the rear seats (two bolts below front lip) and check underneath.

If the door drains clog the bottom of the door will rust out. Rust can also start behind the trim strips on the door where the metal is perforated but this can be stopped if caught.

If the sill drains clog the sill will rust, they start at the back. A partial sill costs 320+VAT and there were several types.

Check the four sunroof drains aren't rusty as they are very difficult to fix if they leak. If they become clogged you'll get water in the footwells. A bad windscreen seal can also cause this, as well as flooding the DME in the process.

BMW Mobile Tradition are now re-manufacturing the kidney grills, badges and early rear spoilers.

Front bumpers and airdams are 1500 quid new and are becoming hard to find used. Pre-84 (roughly) cars have external fog lamps, after that they were built into the air dam. Chrome wing mirrors are also becoming hard to get I believe.

BMW E24 635CSi

If the windows howl at speed don't be too alarmed. They are adjustable for stop height and angle but in the extreme new (very expensive) window seals may be required. BMW Gummi Pfledge rubber restorer can help and is highly recommended.

If the rear electric windows are slow it's due to lack of use. Get some silicone spray with a straw attachment and use it to lubricate the runners. Put them up and down a few times a day and they'll recover. If not you'll need to strip and re-grease them. With the sunroof on tilt they allow for excellent ventilation by the way.

Water leaks in the boot can be caused by failing tail light gaskets, the inner ones cost 40 quid each. The outer ones slot into the chrome surround and may also need replacing. It's a good idea to remove the tail lights to check for rust as there will probably be some. Old BMWs tend to suffer from a bit of condensation in the boot.

The headlamp wash / wipe motors always gunk up. Remove them (grilles have two screws hidden on the inside behind the indicator housing) and clean everything that moves. The control relay is hidden behind the indicator inside the inner wing.

A body pack with rear apron and sills isn't uncommon on 82-87 cars, personally I don't like it.


M30 M102

Six cylinder 12 valve

2.5, 2.8, 3.0, 3.3, 3.4 and 3.5

1968 - 1993

S38 M88

Six cylinder 24 valve

1978 - 1994

For the M635CSi and US M6 see S38 engine problems.

For the rest see M30 engine problems.

The Six has a very big heart, the wonderful M30 engine. It came in several forms on the earliest cars but most examples have the 2.8, 3.5 or the S38 24 valve 3.5 wonderful perfect gorgeous highly desirable M-Tech version.

The 2.8 uses Jetronic-L injection and gives 182bhp. It's alright but you really want the full 3.5 for a higher number of grins per mile. You're more likely to find these as a manual.

The 218bhp, 229lb/ft 3.5 used Jetronic-L injection until mid-81 when it got the excellent Bosch Motronic 1.x system. This does away with points, vacuum advance and all other such mechanical aids and uses a micro-processor to decide when to fire the coil and injectors. It's very reliable and was a real boon to fuel economy. I recently saw an '87 car with 160K miles on the original cap and rotor arm! A worn rotor arm (9 quid) can cause a loss of high end power and even a non-start situation, not to mention horrible fuel economy. If it drink fuel try a new cap and rotor arm.

One of the biggest causes of intermittent stalling on old BMWs is dying relays or dirty wiring. For peace of mind replace the aging main, fuel pump and unloader relays for 10 quid a time. Also a good idea to unplug and clean all wiring connections and body grounds. Only proper Bosch single electrode spark plugs should be used.

BMW approve unleaded only in post 6/87 cars, in practice most people run unleaded on older cars too and I've never heard of pinking or valve seat problems. Expect almost 30mpg on the motorway if you have a light foot. This drops to 22-24 in fast country roads and 17 in heavy traffic. Tank holds 16 gallons and I've managed over 400 miles on a tank, pretty good for a 3.5 litre with 160K miles and much better than and Rover or Jaguar of the time.

The high pressure (3.0 bar) fuel lines don't last forever. Ten years of heat and vibration will have caused cracking inside. They should be replaced with the correct BMW hose (20 quid a metre) to avoid a fire hazard, at the very least trim 10mm off the end. Don't forget the biggest culprit for fuel smells, the 6" line from the fuel rail to the cold start injector (only on 82-87 cars). Best changed by someone with small fingers and a little Vaseline on the ends of the new hose.

Poor idling can have two causes. A sticking idle control valve can be cured with white spirit and a toothbrush. Vacuum leaks are harder to find but even the small hoses, such as the one to the top of the fuel pressure regulator, can cause problems. If in doubt remove, check and clean the entire intake tract as it's not a big job.

M30s have a slightly exaggerated reputation for eating camshafts. This isn't the case unless oil changes have been neglected or the "banjo" bolts on the oil spray bar have worked lose. The head must be removed to change a bad camshaft so make sure any ticking noise isn't major expense. Remember that you need to manually adjust the valves every 30k miles so some ticking may be due to that. M30s seem to have a small oil leak from the front of the block, live with it.

Overheating can cause the alloy head to warp. This may be caused by a bad viscous coupling leading to overheating in traffic. The 15 year old radiator is often the real culprit though. The water pump is only 25 GBP, mechanical parts are not expensive as BMW made this engine from 1968-1993! Non-UK cars with air conditioning use a two speed fan in front of the radiator, this can be a further cause of overheating in traffic.

If the engine seems tilted forwards or out of line with the air flow meter housing suspect failing front engine mounts, not expensive.

Alternator rubber mounts fail around 130K, costs pennies and takes an hour to fix. Circlip pliers are handy. This can be the cause of squealing.

Despite all this the M30 is a very reliable engine. I know of one in Canada with 660K miles and only one top end rebuild at 350K. It's chain driven and unless it becomes noisy the chain will last the life of the engine.

The 286bhp S38 24 valve DOHC engine is derived from the 1979-81 M1 super car and has six throttle bodies. It's very reliable indeed and is a huge tribute to Paul Rosche it's designer. Many people advise a new timing chain at 100K miles but BMW have no such policy. This is an expensive job and unless the car has a lot of track time many owners leave it unless it gets noisy.

You still need to manually adjust the valves but this must be done with shims.


BMW E24 635CSi M30 engine

My own '85 635CSi's engine.

Transmission and Drivetrain

Manual Sixes could have a four speed (early cars), five speed overdrive or five speed dog-leg close ratio box which was standard on the M car. All are very reliable. At very high mileages the shift can become sloppy, this is cured by new bushings for the linkages. Don't worry about a little noise at idle when the oil is fully warmed.

Clutches last well but hydraulics can be tricky to bleed. The clutch should feel pretty stiff but if it's VERY stiff then one of the fork arms may have snapped.

The ZF 4 HP 22 E/H automatic transmission is another story. Early models had a three speed box, this became four speed and eventually had electronic control and a Sport/Economy/Manual switch next to the gear lever.

628CSi's had the non-electronic gearbox with manual kickdown and no sport mode, it's no fun.

Check the fluid with the oil (Dexron II or III) warm and the engine running or you'll get a reading which can be way out. The fluid should be clear and not burnt. It must be changed every 30K or else. Failure to change the fluid means a new tranny around 150K miles so insist on proof. If it's not been changed for a long time then leave it. Changing it now will let all sorts of crud circulate back into the tranny and wreck it, this is why my own car is now a manual. There is also a filter screen under the tranny which should be changed every 60K, a good chance to check and clean the magnets in the drain pan too.

Never ever rev an auto Six at high rpm in park or neutral. This will cause over pressure on the A clutch pack and burn it out, time for a new trany. A pressure relief hole was added in the late 80's to reduce the problem.

Vibration under acceleration means it's time for a new centre bearing which isn't expensive. Other drive shaft vibrations can be caused by worn flex discs at either end. Post 82 cars had a more robust design.

Many cars had limited slip diffs fitted, these have an S or Z in the part number tag. Several ratios were used over the years and early cars had a different design. It's worth checking the diff mounting on early cars but to be honest the diffs are very reliable.


BMW E24 tool kit

If it goes wrong at least the Six has a good tool kit.


Pre-82 cars had four pot front calipers and vented discs all round. Post-82 cars have the same single piston front caliper as E28 five series (69 quid each) and solid rear discs. M cars have four pot brakes just like the M5's. PAGID pads dust a bit but are good value and very effective.

Post-87 cars got the bigger brakes from the E34 five series which were a truly massive improvement. If you have an early car they're a must have and just bolt on.

Watch for vibration when braking very hard from 70mph. This can mean worn tie rods, centre tie rod, control arm bushings or warped discs.

The brakes use a Citroen style hydraulic accumulator affectionately known as "the Bomb" due to it's appearance. I once had a power steering pump drive belt snap at 100mph. The residual pressure in the bomb kept the brakes working for ten times of country roads. If the bomb fails it can result in a very hard brake pedal and dangerously poor emergency stop performance.

Check the ABS light glows yellow and then goes out when the engine starts. Many owners will remove it to hide dodgy ABS (ask me how I know). ABS faults are often caused by rusting stators on the wheels. The front ones are built into the wheel bearings (45 GBP) the rear are separate (22GBP).

Seized brakes can be due to collapsed brake hoses, nothing lasts forever.


Expect some play in the steering, it's just a consequence or not using a rack and pinion system. It can be adjusted out a little but if that's not enough you'll need a new steering box. Power steering isn't overdone so don't be surprised if the steering seems a little heavy.

If the steering goes hard under full lock cornering (especially when cold) it's time for a new filter in the bottom of the ATF reservoir and a fluid change.

The steering box mounts to the front subframe. The mounting isn't as strong as it could have been and has been known to crack. It can be reinforced by welding in some supports.


BMW E24 415mm TRX alloy wheel

415mm TRX alloy, about 16.3".

Suspension & Wheels

In 1978 the Six gained the front suspension upgrades of the E23 seven series for better anti-dive performance. In 1982 the rear trailing arms were angled to 13 degrees to improve road holding, this was the same design all round as the E28. It handles very well and is easy to steer on the throttle giving a rewarding and entertaining drive.

Post '87 cars sometimes had rear self leveling suspension. If this goes haywire it's best to replace it with standard shocks and springs.

Rear subframe rubber bushings perish with age and cause the car to wander. Not that dear to replace but you'll need a special tool to remove the old ones.

If you lower a six more than 25mm the rear trailing arms will never have the correct geometry and it'll be horrid to drive. A 25mm lowering with good Bilstein shocks is the best option. A strut brace is a good idea if the suspension has been stiffened. Get the E28 brace from Demon Tweeks.

The anti-roll bar links and rear Pitman arms (dog-bones) are cheap and easy to replace, just do it. The car will feel more planted and wander less.

Early Sixes have 14" alloys. These gave way to the new TRX style which were good in their day but expensive and outdated now. Best idea is to run 16" wheels and 225/50ZR16 tyres all round. Wheels from any five bolt BMW fit except the E36 three series (wrong offset). New E39 five series wheels need a hub ring to fit but the offset is OK.

Tyres wider than 225 front / 235 rear can cause the car to tramline, 225s are enough. If you fit 17" wheels you'd better have good steering and suspension components or the car will wander all over the place. Don't even think of using 18s.


Almost all cars have leather but pre-82 models often had velour. The Highline, called L6 in the USA, had leather seat backs, head lining, door skins, dashboard, and rear A/C with a cooler cabinet! Try and get a car with rear headrests, they are a really nice design.

I'd avoid seats with electric adjustment. They weigh more and are expensive to fix if they break. The headrest adjustment tends to be the most fragile.

The sports seats are much nicer than the normal flavour, some of the best seats BMW ever made.

If the heater fan only works on full speed it's transistor is shot, not uncommon. The A/C has a separate fan behind the centre console. A/C adds about 50kg to the car's weight and removes the centre storage bin.

Seat mountings can crack slightly around the bolts and need welding. If your seat seems wobbly this may be why.

The back light on the onboard computer often dies. On a right hand drive car you can remove the stereo and replace the bulb unit with a pair of long nose pliers. On a left hand drive model you'll need to remove the centre console, I found this out the hard way.

It's not uncommon for the heating to go haywire. Often it's the heater control valve showing it's age. It's easy to replace (it lives on the firewall on the engine side) but try to buy just the innards as the whole unit it 70 quid. If that's not it then check the wiring to the heater sensors in the heater core and above the driver's foot.

If the interior light delay doesn't work try the sensor in the driver's door handle. This door lock should also be heated when you pull the handle up.

If the tachometer doesn't work or the service indicator lights are all screwed up it's time for repairs. Don't pay 160 quid for a new SI board, get a pair of PCB mounted NICAD batteries and solder them into the dash for a tenner. You must charge the batteries before installation. Some people use the SI lights for remote mounted radar detectors.

These cars can be converted from auto to manual. You need the box, driveshaft, flywheel, pedal box and a few other bits. I've done this and like the result. The auto is better if you only do town and motorway work and has a lovely kick down. Ask me if you want more info.