From Citroen SM Wiki
The Citroen SM is a magnificent machine, but old age has created some very hazardous situations that need your immediate attention.
- The engine oil cooler hoses have separated on more than one car, spraying hot engine oil all over the engine, resulting in immediate fire loss or ruined bearings/destroyed engine.
- Replace the hoses if there is any suspicion that they are old.
- Note that the fittings are Citroen-unique and must be retained from the old hoses.
- Sodium filled exhaust valves have aged poorly resulting in the exhaust valve heads separating and destroying the complete engine.
- Unless you know for sure that the valves have been replaced, pull the heads to check. Do not start or run any I.E. engine or 3.0L engine untill you are certain the sodium valves hve been replaced. Solid modern alloy replacements are easily available.
- Fuel Lines
- On early injected cars, the injectors part numbers are Bosch number is 0 280 150 003. The design of these is faulty and prone to leakage.
- Do not start, drive, or use any car with 003s.
- They were replaced (in later production) with Bosch number is 0 280 150 043.
- Accelerator pump diaphragms fail with age & leak.
- Perhaps less likely, but the plugs sealing the machining passages can wiggle out.
- Consider rebuilding the carbs to renew gaskets and seals.
- Ignition switch
- The alternator feed wire is unfused, and this feed wire passes almost the complete 360 degree circle of the engine compartment, including through the ignition switch. Voltage regulators have an design defect and a tap on the can may lead to grounding of this wire. When grounded it carries so much current it can overheat and short in the steering column. Fit an inline fuse right by the attachment spade on the regulator.
- Lights wiring.
- This can cause a burned wire in the steering column too if the wiring is damaged.