Repair practice

| Cleanliness | Different types of piping | Storage of units | Different methods of Sealing | Hydraulic fluids |


To function properly, the hydraulic circuits on these cars require absolute cleanliness of the hydraulic fluid and units.

1) Cleanliness of work
Before any work is carried out, protectors must be put in place.
  • Covers of cloth or leathercloth on the front wings, the trim panels of the doors, and the seats.
  • A steering wheel glove.
  • Covers for the sidemember trims (Pallas models).
2) Cleanliness of the units
To avoid the ingress of dirt to the units.
a) Before dismantling
  • Carefully clean the area in which work is to be done.
  • Clean the unions and pipe-ends to be disconnected using alcohol for LHS 2 and white-spirit or petrol for LHM circuits.
b) After dismantling
  • Plug all metal pipe-ends and apertures in units with special plugs sold by the Spare Parts department.
  • Protect the flange unions of pipe assemblies with self-adhesive tape ; also the plastic pipes may be dealt with in the same way.
  • Protect rubber pipe-ends by plugging with a suitable sized object (e.g. a cylindrical pin).
c) Rebuilding
  • Clean the pipe assemblies and unions to be replaced with alcohol for LHS 2 and white-spirit or petrol for LHM circuits.
  • Do not remove the plugs from pipes and units until the very last moment.
3) Cleanliness of the fluid
Never re-use fluid that has been in service.


1) Metal piping
There are two sizes of metal pipe:
  • 4.5 mm external diameter.
  • 6.35 mm external diameter.
  • Only use standard pipes as supplied by the Spare Parts department; except for the longitudinal pipes running the length of the chassis, all the pipes are pre-shaped ready to be fitted.
  • Pipes which have been pressure-tested are marked with a coloured sleeve, Red for LHS 2 systems, and Green for LHM. They must be used only on cars using the appropriate fluid.
  • No repairs whatever may be carried out on these pipes, for reasons of safety and reliable service (e.g. brazing, sleeving, non-standard end-fittings)
2) Plastic Piping
  • These pipes are used for seepage returns (e.g. Suspension cylinder returns, height corrector returns,etc.) and for petrol supply.
  • It is permissible to repair these pipes by sleeving, providing that a pipe does not have more than two sleeves which must be at least 800 mm apart. The sleeve must be glued and when the glue has hardened the joint so made, must withstand 5 kg/cm2 (72 psi) pressure from a compressed air line.
  • The glue to be used is RILSAN cement. Sold by Etablissements BOYRIVEN, 37 bis Avenue de Villiers - NEUILLY-SUR-SEINE.
3) Rubber piping
  • These pipes are used for the operational returns from units, the supply from the reservoir to the High Pressure Pump, and some seepage returns.
  • All these pipes are marked Red or Green in accordance with the fluid which they are to be used, LHS 2 or LHM respectively.


  • Units must be stored full of fluid and firmly plugged, protected from dust and knocks. Parts must be used in strict rotation so as to keep parts in stock for the minimum time possible.
  • Rubber seals and pipes must be stored away from dust, light, and heat.


1) Sealing by metal clip

This method of sealing is used to secure rubber pipes onto steel and plastic pipes and unions.

When fitting:

  • place a rubber protective ring under the clip.
  • take care not to cut the end of the pipe.
2) Rubber Sleeve Seals

These seals ensure the sealing of steel pipes fitted to hydraulic units.

  • Sealing is achieved by the deformation of the sleeve under the action of pressure.
  • The seals must be replaced every time a pipe is disconnected.
  • Do not forget to remove the old seal, then clean the bore before rebuilding.
  • Always fit the seal to the pipe dry, so that about 2 mm of the pipe projects through the seal. Centralise the pipe in the bore and ensure that the pipe goes fully home.
  • The swelling near the end of the pipe holds the seal in place.
  • Start the union nut by hand and tighten moderately (1 mkg) (15 ft lbs).

Seals to be used with LHS 2 are painted Red.
Those for use with LHM are Green.


Ring Seals

  • Sealing is ensured by the deformation of the seal under the influence of the fluid under pressure. In order that the pressure may achieve this, the diameter of the ring is less than the width of the groove and greater than its depth.
  • Three types of ring seals are employed:
    • Marked Red for LHS 2
    • Marked Green for LHM
    • Marked White for either.
  • Seals with White markings are only used between static components.
  • The marking on a seal must always face in the direction from which the pressure is coming. In addition the seals must be soaked in the appropriate fluid before fitting.
4) Sealing Plates

These are found at flange joints between pipes and units.

  • When fitting, ensure that the holes in the plate correspond with those in the flange.
  • The plates and the seals are sold separately.
  • The seals are marked with White and are fitted to vehicles using either type of fluid. They must be replaced at each dismantling.
5) Teflon Seals
  • These ensure sealing of items subject to large or frequent movements (e.g. hydraulic steering-rack piston, suspension cylinder)
  • Teflon seals may be used with either type of fluid.
6) Identification of Seals
  • Workshop sheets, available from the Spare Parts department, show clearly which seals (Red, Green, or White), are necessary in the course of repairs or the over-haul of a hydraulic unit.


1) L.H.S. 2 (FromSeptember1964 to September 1966).

This fluid is almost colourless, having a slightly amber tinge. Its smell is reminiscent of ammonia. it must not be used on vehicles with master-cylinder braking systems, (it causes deterioration of the rubber cups).

For Suppliers, see Technical Bulletin no. 29-D.

2) L.H.M. (Since September 1966)

This fluid is green in colour. It is of mineral origin, and is similar to engine oil.

L.H.M. fluid is also used on N and P vehicles, and since September 1969, on AMB-3 and AM.3 vehicles fitted with disc brakes, also,since their introduction, on the GS and SM.

For Suppliers, see Technical Bulletin no. 76-D.

NOTE : From September 1966 to December 1968, LHS 2 was still supplied in vehicles for the U.S.A. and Canada.

3) Contents of the systems
DS = 6 litres or 10.5 Imp. Pints
ID = 5 litres or 8.8 Imp. Pints.
The difference between Max and Min = 1 litre or 1.75 Imp. Pints.
4) Draining the system

The system should be drained and refilled with fresh fluid every 30.000 km (18,000 miles).

Drain after causing the greatest possible amount of fluid to return to the reservoir.

(Suspension in low, main and brake accumulators empty).

5) Cleaning the filter

The filter must be thoroughly cleaned every 10.000 km (6.000 miles) (A clogged filter leads to inefficiency of the hydraulic system).

The filter should be cleaned in alcohol (LHS 2), and white-spirit or petrol (LHM), and then blown through with compressed air.

6) Advice in the event of fluids being mixed. (See Information Bulletins nr. 32 and nr. 72).

An accidental mixture of fluids in the hydraulic systems (LHM in an LHS 2 vehicle, or vice-versa) causes a rapid deterioration of all the rubber parts in the system (Seals, diaphragms, etc.). The severity of this deterioration is a function of the amount of fluid mixed, and the length of time that the vehicle is operated with this mixture.

1) In the event of a recent mixture of fluids, if there appear to be no malfunctions of the hydraulic system, drain the system after returning as much fluid as possible to the reservoir. Then flush the system using Hexylene-Glycol for LHS 2 vehicles, and normal flushing oil for LHM vehicles. Check the suspension spheres, main accumulator and brake accumulator, for pressure and verify that the diaphragms are not deteriorating. If they are within the specified limits, refit these units.

Refill the reservoir, bleed a large amount of fluid through the braking system do not re-use the fluid bled off. Then check the action of the suspension and the brakes. Allow the vehicle to be used for about a week.

Check at frequent intervals that the suspension and brakes are functioning correctly. After two weeks use, drain, refill and bleed the system again.

2) If a vehicle has been used for a considerable time with a mixture of fluids, malfunctions will be found in the hydraulic system. The majority of the rubber parts will have deteriorated. Take off all the hydraulic units and change all the seals and rubber parts. Change the main and brake accumulators, also the suspension spheres. Flush out all the units and piping with petrol, then alcohol for LHM vehicles and with alcohol, white-spirit or petrol and again with alcohol for vehicles using LHS 2. In both cases, blow through with compressed air. Change all rubber pipes and dust protectors.

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