Engine Autopsy

Citroën’s Douvrin in bits.

Efficiently-designed team effort between Peugeot, Citroën and Renault

If you bought a large French car in the Eighties or Nineties, there’s a good chance you also bought one of these. The Peugeot 505 and Citroën CX used this engine in 2.0-litre and 2.2-litre form. Renault put it in the 18, 20, 21, 25, Espace, Fuego, Safrane, Trafic, Master and – in diesel form – the 30, giving it a lifespan that ran from 1977 to 1996. The version seen here is a 2.2-litre example from a Citroën CX TRS.

This efficiently-designed all-alloy engine was the product of an alliance between Peugeot/citroën and Renault. It came to life at Douvrin, a small town in northern France. The same factory built the little ‘suitcase’ engine used in the Peugeot 104 and related small hatchbacks, plus the Douvrin V6 shared with Volvo, De Lorean and others.

[A] CAM COVER This is a hefty doubleskinned pressed steel construction, presumably to help suppress the clatter of the large rockers that hammer up and down directly beneath it.

[B] CYLINDERHEAD A neat crossflow design with the exhaust ports at the top (as we see it) and inlets opposite. It didn’t vary between the 2.0-litre and 2.2-litre, as only the stroke was altered. There were 12-valve versions of this engine used by Renault in both sizes, featuring twin inlet valves for a hike in power output and a livelier character.

[C] CAMBELT AND TIMING WHEELS All variants used a single belt-driven overhead camshaft. Here we see the cam pulley (top), tensioner (middle left), auxiliary shaft pulley (middle right) and crank pulley (bottom). The tensioner is spring-loaded and shifts itself to the correct position when its mounting bolts are slackened, taking up slack in the belt. The crank pulley drives a pair of V-belts in front of the cambelt. The rear belt drives the water pump and alternator; the other an optional airconditioning unit or, in non-citroën applications, a power steering pump.

[D] BLOCK The block is aluminium with cast iron ‘wet’ cylinder liners that can be removed and replaced individually, sealing at the base with a large O-ring. The round aperture on the lower left lines up with the oil pump drive of the auxiliary shaft, so might have been envisaged as an alternative distributor drive on certain versions of the engine. Here it’s covered with a plate and does nothing at all, aside from allowing the oil pump drive to be extracted. Next to it we can see one of the two studs that attach the fuel pump.

[E] HYDRAULIC PUMP PULLEY This Citroën-specific item fits to the rear of the camshaft, which pokes out at the flywheel end of the cylinderhead. It drives a short V-belt that powers the hydraulic pump that brings the CX'S brakes, steering and suspension to life.

[F] SUMP A very robust aluminium casting, which is necessary for the CX installation as it does a significant loadbearing job. Mounts can be seen left and right, with a larger central mount at the back (or top as we see it) that stops the drivetrain twisting under torque.

[G] CAMSHAFT The Citroën version of the camshaft has one unusual feature – a long tail that protrodes from the cylinderhead to drive the hydraulic pump pulley we’ve just seen on the opposite page. The little skew gear at the same end drives the distributor, which slots at 90° into a housing that

fits around the camshaft tail. The small arch-shaped pressing above is the camshaft retaining plate.

[H] ROCKER SHAFT This contributes to the Douvrin’s cost-efficient design, doing away with the need for a separate cam carrier or cam followers. Those five

large bearing caps clamp the camshaft to the top of the cylinderhead, while the shaft that runs through them carries the rockers. The stubby end of each rocker contacts a lobe of the camshaft under the rocker shaft. The longer end bears on the top of a valve stem and has a threaded adjuster to set the valve clearance.

[I] VALVES AND SPRINGS The eight valves are entirely conventional – one spring each, one valve cap, one pair of collets. The valve heads are relatively large, leading to favourable gas-flow that helped the engine respond well to fuel injection and turbocharging.

[J] OIL PUMP The oil pump rests at a jaunty angle in the front third of the sump – that strainer plate would be horizontal. That means the skinny shaft that drives the pump runs at a diagonal up into the side-gallery in the block where the auxiliary shaft resides.

[K] PISTONS AND CON-RODS The 2.0-litre is an oversquare design. Even after the stroke was extended by 7mm to make it 2.2-litres, as seen here, it’s only 1mm larger than the bore. Slightly dome-topped pistons and broad H-beam rods look sturdy, but the size of the big end bearings suggests that careless servicing would limit mileage between rebuilds.

[L] AUXILIARY SHAFT This is turned by the auxiliary pulley. The stubby drive above it fits onto the top of the oil pump’s slim shaft and is turned by the skew gear on the auxiliary shaft. At the extreme right is an eccentric that operates the plunger-type fuel pump mounted to the side of the block. The shaft’s retaining plate is below it.

[M] CRANKSHAFT The steel crank is a conventional counterweighted design with five broad main bearings.

[N] THRUST WASHERS Fore-and-aft crankshaft movement is controlled by just two thrust washers, both of which fit into the block (rather than the bearing caps) either side of the secondfrom-rear crankshaft journal.

[O] BEARING CAPS These chunky main bearing caps locate the crankshaft in well-aligned bearing surfaces and contribute extra rigidity to the aluminium block. They also house the lower half of the lip-type crankshaft oil seals front-and-rear.