Looking After the SM
Let’s put this plainly: for annual maintenance costs, expect to spend (or invest) between €500 and €3 000 for upkeep on an SM, depending on its condition, maintenance frequency, and, of course, your location in the world. However, bear in mind that the engine can be a significant expense, with an overhaul easily exceeding €10 000, and €10 000 if the transmission needs some work, you could be looking at €15 000 or more.
That being said, we have, so far, been fortunate enough to enjoy our SM with minimal investment. Alongside regular maintenance and a major makeover of the upholstery, we’ve tackled just a few other key issues: overhauling the suspension cylinders, replacing a height corrector, stopping pesky rear brake leaks, and reviving the air conditioning, which had succumbed to a tired compressor. We have also upgraded to a set of robust stainless steel silencer pipes. An engine preventative overhaul is, however, planned soon. We’ll keep you posted!
When looking for an SM, keep in mind that, while the SM’s body boasts a tougher build than the DS and has a much-improved resistance to rust, it’s not completely immune. The rear section, in particular, can fall prey to decay, so don’t forget to check beneath that boot floor carpet for any lurking issues. On the bright side, sourcing spare parts for an SM is relatively straightforward, much like the DS, although your wallet might feel the pinch in this case! Specialists in France, the Netherlands, and the UK are excellent sources for these parts. If you become a member of the SM Club de France, you’ll benefit from remanufactured parts at reasonable prices. Our ultimate advice? Avoid incomplete cars and steeper-than-average deals when eyeing an SM. A thorough inspection of the vehicle’s completeness and condition is essential before you make that leap.
There are dedicated clubs and various resources available to assist you in the joys of buying and maintaining an SM, although not all of them are in English. Here are some links to help you get started.
While many videos online put the spotlight on the SM, the rlbatch1 channel takes a deeper dive with comprehensive servicing instructions that are truly invaluable. I can’t help but admire Sean Patrick’s insightful articles on Driven To Write which brilliantly capture the essence of this iconic motor. And let’s not forget the buzz surrounding the freshly restomodded SM2 by Gallet Automobiles. It is an exciting time for SM enthusiasts!
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Key Data for Routine Maintenance of Your 2,7 Carburetted 5-Speed SM
- Fuel tank: 90 litres (petrol).
- Engine lubricant: 7 litres mineral oil 20W50 (6 litres without filter).
- Transmission lubricant: 2,25 litres gearbox oil TOTAL SAE 80.
- Hydraulic circuit: 5,4 litres LHM fluid.
- Engine coolant: 13,5 litres.
- Spark plugs: gap 0,6-0,7 mm; original: Bosch W 200 T 30, replaced by: NGK BP6ES / Bosch W7DC / Bosch WR7DC+ / Champion N9YC.
- Battery: 70 Ah.
- Tyres: Michelin XWX 205/70 (originally 195/70 for the carb version). Recommended pressure front/rear: 33/30 psi.
- Suspension sphere pressure (front/rear): 40/26 bars (split spheres).
Low-Mileage Operating Intervals
- Yearly (max 5 000 km): change the oil and filter, lubricate doors, bonnet, handbrake, horn, distributor.
- Every 2 years (max 10 000 km): yearly maintenance + renew coolant, lubricate front suspension and steering (at 10 points). Check, adjust, or replace: spark plugs, contact points, drive belt tension/condition.
- Every 4 years (max 20 000 km): 2-year maintenance + renew gearbox oil, renew LHM and clean filter with petrol and air (max 30 000 km), lubricate rear suspension ball bearing, clean air filter, blow clean the water and oil coolers, lubricate height correctors, front wheel alignment, tyre balancing, check, adjust, or replace: fuel pipes, 6 hydropneumatic spheres, parking brake, brake pads, hydraulic hose connections, ground clearance, front suspension, and steering components.
- Every 10 years (or when reaching the annotated km): 2-year maintenance + check valve/tappet clearance (max. 10 000 km), replace fuel filter (max. 20 000 km), replace distributor capacitor (max. 20 000 km), replace ignition coil (max. 60 000 km), change all drive belts (max. 50 000 km), check front suspension ball joints, steering rods, and rear swinging arms for any play, adjust clutch clearance.
- At 20 000 km: adjust the tension of secondary timing chains.
- At around 60 000 km: 20 000-km maintenance + replace the primary timing chain and its tensioner.