Purchase Advice

From Citroen SM Wiki

For aspiring SM owners, but possibly also for owners who want to 'assess' the condition of their SM, this section provides information on points you should watch, preferably before buying an SM. It does not provide in-depth technical information. For more detailed information check the linked pages which advise you were to look. First try to get into the SM world, become a member of an SM club and find out which specialists are good, and which are not. Do not have your new SM serviced by just any garage or shop.

Not always a happy story

The nature of the SM doesn't make this section 'happy reading'. A lot of things probably will be wrong with SM's you consider for purchase, or will go wrong in the future. Comparing the SM with other exotic cars can illustrate what is meant.

Consider a Jaguar E-type. The E-type, a car as beautiful as the SM, is not less of a nightmare. There is one important difference: there are enough E-types for specialists to take notice. That is to offer service and parts. Whether you live in the UK, the USA, or Germany, somebody in the neighborhood will understand E-types. That's where the SM is a different animal. Few people understand her inner life. Some of those however think they do! Always be careful before you spend your money.

Decide what you want from an SM

Before taking the plunge and buying an SM consider the following points. First, what are your own capabilities in diagnosing trouble, maintaining and repairing a complex car? Second, what are your objectives?

  • If you are rich and want the SM as an 'objet d'art', go ahead. You won't drive it that much and the few SM specialists will make you happy. You will own possibly the finest 'Grand Tourer' ever made.
  • If you are not that rich, and moreover don't know the difference between your left and right hand, and don't or can't be bothered to work up your understanding but still want an SM, to drive frequently, stop right now. Consider an MG or a Volvo.
  • If you are not that rich, and moreover don't know the difference between your left and right hand, but still want an SM, to drive from time to time, study this section as carefully as the contract before you buy a house. Then buy the best SM you can find!
  • If you are rich or poor, but have grease under your fingernails, all right! Buy an SM. Correctly fettled they are reliable and a joy. But anyway read this section.

The basis of our information

The experiences and views we present in this section are based on a number of articles in the specialized press. Moreover we have been involved with SM's for a long time and know where they 'hurt'. The magazines we used are - for an extensive list please refer to our literature section:

  • Retroviseur, number 55, 1993
  • Gazoline, number 33, 1998
  • Auto Retro, number 3, 1998

General points to watch

When talking with sellers of SM's there are a number of general things to watch. Ask for them!

  • How long has the car you are considering been 'idle'? Cars which are not used will deteriorate quicker than used, and serviced, cars.
  • If the car has been idle for a long time, how was it stored. Dry? With enough fresh air circulating? Or in a an old barn which smells like cows urinating all over the place? Your SM will suffer for it!
  • The engine has been overhauled? Can I please see the bills? Who did the overhaul by the way? (It costs so much money, people will remember, when they are honest!)
  • The engine is sitting next to the car? Like the whole interior. How do you know everything is there? Unfinished restorations can end in a nightmare for the next owner.
  • When you test the car, or maybe after you buy it, check the tires. They may be in a bad shape. Especially if the car hasn't been used for some years.
  • Use eyes and nose: if you smell petrol (injection cars!) or see 'wet' spots on hoses, memorize the number of the local fire brigade!
  • Always check the 'vital' fluids, that is engine oil, LHM (NOT BRAKE FLUID!) and the coolant level (and quality).
  • When testing a car do not presume anything important will be working (like brakes).


Check the papers; does the serial number match between the car's document and the body? The numbers are under the hood and should be quite visible.

Please refer to the Identification page.

A well documented car, which shows its history and proves its maintenance is a good start!


  • If you can drive the car but the suspension doesn't feel 'soft', but feels like a sports car- 'hard', you'll need new/overhaulled spheres- 'balls' in the suspension system.
  • If their is a 'clicking noise' from underneath the bonnet every 15 seconds, or more often, and you hear the hydraulic pump activating itself all the time, the sphere which stores reserve-pressure is probably shot.
  • Both can be pressurized, but only when the spheres diaphragms are OK.
  • Test it using a (specialists) test bench.
Any pressure below 10 bars will usually mean that the sphere should be replaced, since the diapraghm can be damaged when used at very low pressure.
There are actually two types of spheres; the ones that can be opened to change the diaphragm, and those that are sealed and can not be opened: these are to be replaced if malfunctioning.


Replacements are not cheap. If an exhaust is made of stainless-steel - which doesn't rust - has been fitted, good for you.


  • Always check the level of motor-oil. It should be within the reduced area at the bottom of the dip-stick
  • Check quality of hoses between engine and oil-cooler. Don't hesitate to replace them.
  • Check level of oil in gearbox
  • Check level of oil in differential (on cars with automatic gearboxes)\
  • Check quality of oil in (manual gearbox). Hydraulic oil for the power steering control and gearbox oil are only separated by a rubber membrane!
  • Maintenance tip
The little shaft with splines which drives the oil pump is too weak.
Replace it! expensive but worthwhile!


The engine has no characteristic noises, it is very quiet when in good condition. Beware any loud tapping or clattering noises. Chain noises are not always a problem provided they are attended to immediately, but the primary chain can have problems that will cost money to fix.

Valves and chains

Exhaust valves are hollow and filled with sodium salt for better cooling. They will break, especially when the engine has not been running for a long period, due to corrosion. Nothing to diagnose up in front. Solid valves are readily available now.

Maintenance tips

  • Valves must be adjusted every 10.000 km
  • Chains need your attention:
    • Secondary chain: tensioning required every 10.000 km. Some people say every 20000 km. That's up to you!
      • Tensioner of secondary chain to be replaced every 60.000 km
      • Primary chain tensioner and chain: replace every 60.000 km

The primary chain must do a lot of work. It transfers all the power to the alternator, hydraulic pump and airco. But it can only be inspected by dismantling the car. That's quite a lot of work. If you don't have any reliable information on the history of the chains, it is probably worth the money. If it's silent, experts say, that doesn't mean it is all right!


Important: check condition of rubber hose between fuel rail and injectors. If any of the rubber pipes have external fabric re-inforcement, change IMMEDIATELY.

In case of leaks or wet spots: be very careful: FIRE! Fire!

Use hose clearly printed with 'fuel injection' on it it is readily available anywhere.

Maintenance tips

  • Fuel-filters in the injection system need renewing from time to time.
    • Quite often filters are just forgotten. Remember: they are the only defense system for your injectors against a hostile world (debris from corroding steel fuel tanks).
    • Injectors can be cleaned using ultrasound technology. Ask your dentist.
    • Earth-connections are important for a good functioning injection system


Spark plugs: recommended Champion N9YC


A weak point on the SM. The diodes are too close to their rating. Replace with modern ones. The output of the alternator is not enough by modern standards- night traffic jams, air conditioning running, lights ablaze. There are some modern ones that can be fitted BUT TAKE ADVICE.


Bad Earth connections give problems, especially in cars with fuel-injection. Small electric engines in doors to lower windows sometimes not working or weak because their ferrite permanent magnets have come unglued inside. Easy to re-glue!

Gearbox (manual)

  • Good and strong
  • Sometimes 2nd and 5th gear synchros are worn.

Gearbox (automatic)

  • On 1972 models, the transfer gear set is geared quite low. On 1973 models the transfer gear set is much better suited to the engine. In the USA the automatic transmission developed a reputation for being unreliable, due in no small part to the failure of many owners to adjust the brake bands (which must be manually tightened - a simple operation, which if left undone will lead to early failure.)
  • Check oil level. Black transmission oil is bad sign. Also if it smells burned

Maintenance tips

  • Oil changes important
Remember: there is different oil in the Borg Warner gearbox and the differential. The ring and pinion should have gear oil (small dipstick near the torque convertor housing). The Transmission should have FORD TYPE "F" FLUID ONLY.
  • Friction bands need adjustment. Loosen the lock nut (3/4 inch deep socket). Tighten the band adjuster (5/16 square socket) to 7 ft.-lbs, then back off 3/4 turn. Tighten the lock nut to 33 ft.-lbs. Repeat on opposite side.

Front suspension

It sounds like a horror-story, but the French magazines used in making this purchase advise, recommend checking the point where the front suspension is attached to the car. Over-enthusiastic use may result in the breaking of the attachments of front suspension to car!


SM's don't rust as badly as many cars. But there is enough to keep you amused:

  • Rear mudguards (fenders) quite a lot of the time are damaged, and are repaired badly.
  • Check their condition. You won't find new ones.
  • There may be corrosion in the welds where the outer and inner rear mudguards meet (in the rear tire area).
  • Front and rear glass is glued in place. It can hide nasty surprises.
  • Seal on the 'third door' doesn't seal that well. Water may have ingressed in the boot (trunk) of the car, starting corrosion. Lift the floor mats and find out.
  • Between aluminium hood and embellisher up front you may have galvanic corrosion.
  • The aluminium hood may be 'holed'. (Very small holes, sometimes covered by what's left of the paint.
  • Check for paintjobs (inspect carefully the rubbers and other traces) and make sure the shining paint does not hide bad spots or worse. Use a magnet to inspect the body: plastered areas are not magnetic.. Check if weird 'cover up's are hiding rust.


  • Check condition of chair-adjustments. Internal mechanism may be broken
  • Check condition of upholstery. It's expensive to renew

Bringing your new SM home

If the car has been standing still for a long time, do not drive it. Fire!

Although it will cost you a fair sum of money, a damaged engine will cost you a fortune: have the engine checked first by a specialist, especially the exhaust valves. These should be replaced!