It’s well recognised that the D is a beautifully designed car, but there are a few places that hide trouble.
For example, there are 5 hydraulic pipes that go from the driver”s side to the passenger side under the gear box. In the factory assembly a piece of foam would have been inserted to stop the pipes rubbing on the gear box. Take off the engine tray to make sure the foam or insulation is there.
Back in the 90’s I remember a DS broke down with no connection between the engine and the wheels. It turned out to be the shaft between the clutch and the gear box. The splines had corroded because of water getting into the join in the middle of the gear box. Moral- dont steam clean the engine, it may also damage the two bearings in the power steering. These are at the end of the steering column below the rack tensioner.
In the inlet pipe to the Weber carburetor is a wire mesh filter. You need a 19 mm spanner to remove it. Wash filter with petrol or similar and reinstall. Now you can be sure your Cit wont go into kangaroo hops because of petrol starvation.
If you run with your spheres significantly below pressure you will stretch the diaphragms and they may then leak.
At some time or another the radiator would have been removed. When re=installing, make sure the bottom metal pipe does not rub on the power steering pipes. Protecting the hydraulic pipes is a good idea. Also make sure when the clutch pedal is depressed the adjustment bolt does not touch the power steering pipes.
Whilst we are in the engine bay, I have doubts about the overall benefits of engine steam cleaning. There are a number of bearings that are not well protected against steam pressure. The front of the HP pump bearing is a case in point. I have found corrosion in these bearings in at least 5 cases over the years. Top of the steering pinion is another. The gear box has a join in the middle and i have seen the results of water getting in the gb and corroding the splines. The result- 1000ks from home and grounded.
If when braking you hear a gentle swishing noise, it could be because the engine mounts have sagged allowing the brake discs to rub a groove in the engine tray.
The cam shaft pulley is rivetted on to a boss that fits on the shaft. I have seen the rivets fail.
The rest of this collection of observations is about corrosion. The roof seal is covered by a number of dress strips. Water can be sucked under the strips and corrode the roof seal gutter. It is true the steel roof gutter is available as separate parts- but what a job. Whilst some corrosion safe guards are built into the design, the holes have to be kept clean.There are two holes at the back of the roof under the indicator trumpets. It allows water that gets inside the roof to drain and go through the holes and down the outside of the steel quarter panels. If the holes are blocked then the water is channelled down the quarter panels..
On either side of the boot lid are the springs that hold up the boot lid. The bottom oof the spring tubes are the stays welded to the body. The water must be allowed to go through the stay. Rubbish also sits in the crevice that has the rear windscreen on one side and the boot hinge on the other.
Below the front door pillars are a couple of rubber flaps. Presumably these protect the underneath of the mudguards and doors from flying stones that are kicked up by the front wheels. Remaove the rubber flaps and have a look underneath. Also in this area are the two front mudguard supports. They should have plastic plugs in them to stop water getting in.