Heliminating Hydraulic Hassles

Heliminating Hydraulic Hassles

Selecting a car to buy in the US has the added challenge that it is a big country and there are few Citroëns. This means that ads. need a lot of screening by asking questions of the owner, before buying an airline ticket. It is a sort of tyre (tire) kicking by phone or remote hydraulic system diagnostics. While bombarding one remote owner with questions, I realized that I had, hard-wired in my brain, a standard check list for hydraulic diseases and that this might be of general use. So here it is and it assumes that you have none of those useful gauges that I left at home in the garage. Some tests can only be verified when you see the car. Ask and the bet is that the owner won’t know without checking.

Test	Result	Probable Cause
Look in the reservoir	Yellow/Green LHM	Fluid old, damp or diluted with engine oil
	Dirty	Never changed, flaky hoses
	Clean, bright green	Lucky you – carry on
Start the engine, height normal	Slow to rise, pump runs for longer than 30 secs.	Weak pump, split inlet hose, loose clamps
	one end rises only	stuck height corrector
	car fails to level, one end rises and falls	faulty linkage to height corrector or faulty corrector.
car rises to normal height, pump runs 5 secs max every 25 secs min.	going well so far, jump next three.
	pump runs more frequently	suspect pump, regulator, accumulator or system fault.
Look in reservoir	active fluid return	suspect leaking steering or rarely brake valves
	little return flow	regulator or accumulator
Turn steering from side to side.	pump runs continuously	flat accumulator/front spheres
Stop light stays on more than 5 secs. of engine starting	If pump cuts out –	accumulator or regulator fault else pump, fluid level or system fault.
Press down each wing and release	solid feel, no bounce	flat sphere
	soft springy feel, bouncy	faulty shock absorber valve
	soft spring feel, damped bounce	that corner is OK
Sit on the front bumper (fender)	Front sinks and then rises within 20 secs	OK
Get off	front rises and then with a hiss settles within 10 secs to level	OK
Test	Result	Probable Cause
	Test fails	Height correctors or linkage faulty
Repeat test at rear		As above
Set height lever to low	Car sinks to lowest level with a clunk	Worn stops
	Car sinks and settles level	OK
Set height lever to high	Car takes longer than 20 secs to reach level max height	faulty pump, not enough fluid, bad height corrector setting, lever need adjusting
	pump develops loud rattle	not enough fluid
select the three middle height settings 30 secs each	no level difference between them	lever settings wrong, correctors play too wide.
Height normal, press brake button or pedal repetitively	stop light comes on or pump runs frequently	faulty regulator, flat accumulator, brake valve faults.
Height maximum,	check for leaks.	Any leaks with pressure behind them - stop further testing
	spotty leaks	split boots, plastic return pipes, faulty seals
Normal height, stop motor, ignition on	stop light comes on within 10 secs	faulty return or safety valves
press brake repeatedly	stop light comes on within 5 pushes	flat brake accumulator, faulty brake or safety valve
Check visible pipes	brazed, soldered or joined repairs	work hardened, may be more failures to come.
Check sphere markings	Pressures do not agree with manual	suspect incorrect replacements – can make handling dangerous

This may not diagnose all problems down to the component level but will give a good guide as to the potentially more expensive parts to check out or replace. Dirty or wrong fluid may not look expensive but it can warn of serious problems to come. Spotty leaks are a nuisance and can be expensive if they come from damaged nylon return pipes or the steering. If spheres are flat, there is a risk of mechanical damage to the suspension. Inadequate front system pressure storage or steering leakages can make steering forces unpredictable and dangerous – watch the test drive.

These checks apply to all hydraulic models except the single piston pump iD’s and CX and certainly not to the 2cv. You can wait all day for these to come up to altitude.

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