STOP light on dash with low lhm fluid level

This is the Forum for all your Citroen Technical Questions, Problems or Advice.

Moderator: RichardW

Post Reply
charentejohn
Posts: 479
Joined: 16 May 2011, 14:58
Location: France
My Cars:

STOP light on dash with low lhm fluid level

Post by charentejohn »

Out today and the STOP light and the (!) next to it came on, so as all seemed ok I drove straight home. I was in the wilds of France so a careful drive home seemed the sensible thing to do. When I got within 1km of home the light went out, typical.....

I read info here and then read my workshop manual and seems low LHM is the problem, I had a 1L container in the boot so set the car on high (engine hot) and proceeded to carefully add liquid. Once all 1L was gone and still no movement of the gauge I thought ??????
I looked under the car and no obvious leaks, is atands on a light grey concrete floor and no marks of fluids underneath. Unless LHM tends not to mark floors ?

I used the scientific 'how much is in the reservoir' test and stuck my finger in the filler hole and - nothing. The car was on high, motor running, orange level indicator on the bottom.
After adding 1L and putting the car in normal, engine still running, the level indicator filled up but still nothing in the tank. Stopped the engine and waited 5 mins and still the same, I worried the fluid would suddenly return.

Questions are...........

Is it normal to need so much fluid ? I bought the car a few months ago and did not check fluid but the seller left a 1L bottle in the boot. So I assume it was for regular topping up.
How much would a car use in general, it says to check every 10k Km so how much if any would I expect to have to add after that no of Km/Miles.

How full should the reservoir be when engine stopped and car in normal height setting ? Currently can't see any fluid in the reservoir.

I am off out shortly to buy some more LHM so can top up properly but if down so far as to give a warning how much would you normally expect to add ? I assume it must have been going down for a while.

Will this have done any real harm ? Hopefully not as it must have been borderline and I only drove 6Km with the light on.

I will pay more attention in future :oops:
You must be the change you want to see in the world - Mahatma Gandhi
Xantia HDI 90SX C3 2005 and C3 2006 both 1.4i sensodrives
addo
Sara Watson's Stalker
Posts: 7098
Joined: 19 Aug 2008, 12:38
Location: NEW South Wales, Australia. I'll show you "Far, far away" ;-)
My Cars: Peugeot 605
Citroën Berlingo
Alfa 147
x 93

Post by addo »

Do you think the ride has recently got harsher?

Does the red light go out on startup, faster than it did before?

I would also have a good sniff inside around the brake pedal, in case the oil is under your carpet!
charentejohn
Posts: 479
Joined: 16 May 2011, 14:58
Location: France
My Cars:

Re: STOP light on dash with low lhm fluid level

Post by charentejohn »

Thanks Addo, I did think the ride was a bit harsher especially on potholes but not drastically so.
I had a good sniff around and checked the carpets and no LHM.

The light did seem to be staying on a bit, normayy out after 3-4secs but recently I have reversed out of the garage before it went out.

I did some citrobics and set to low the light came on again after it had been in low for a minute or so, only on for 30 secs then went out. Been fine since then.
I did a final top up of about 200ml so it has now taken the full 1L and the 'flying saucer' is now on the top line, so a bit high, but at least not right at the top of the glass.

I apologised to the car because I did promise to give it a good going over and haven't done it, I will now.

I am guessing 1L (25% of capacity) is where it would start complaining, Still nothing to see in the reservoir though, should there be ?

Perhaps 1L was used due to a slightly low level being ignored. I have noticed if that happens the levels drop faster as the amount of any fluid is reduced. So not checking could have made it worse over time, if I do it once a week now I can hopefully control it.
You must be the change you want to see in the world - Mahatma Gandhi
Xantia HDI 90SX C3 2005 and C3 2006 both 1.4i sensodrives
User avatar
Xaccers
Posts: 7654
Joined: 07 Feb 2007, 23:46
Location: Milling around Milton Keynes
My Cars:
x 184

Re: STOP light on dash with low lhm fluid level

Post by Xaccers »

Remember with the car on high the LHM level is at its lowest in the reservoir so you aren't likely to be able to reach the LHM with your finger.
The orange disc needs to be between the two red lines on the resevoir bubble when the car is on high.
It could be that one or two old spheres' membranes have ruptured so they've filled with LHM dropping the level.
1.9TD+ SX Xantia Estate (Cassy) running on 100% veg
1.9TD SX Xantia Hatchback (Jenny) running on 100% veg for sale
Laguna II 2.0dCi Privilege (Monty)

DIY sphere tool
User avatar
Chris570
(Donor 2020)
Posts: 1461
Joined: 12 Dec 2009, 14:10
Location:
My Cars:
x 29

Re: STOP light on dash with low lhm fluid level

Post by Chris570 »

Sorry to nit pick but you said that you can reverse out of the garage before the stop light goes out, please don't. when the stop light is on it could be for many reasons indicating no pressure ergo no brakes. I always wait for the light to go out just in case. Sorry to point it out but incase anyone else reads that.....
2006 C5 HDi 170
1998 Xantia Activa S1
1971 D Special
2006 C3 1.6 HDi SX,
CitroJim wrote: I'm a pink fairy
A 1/3 of Team WFA 'Clarkson'
User avatar
Mandrake
Posts: 8615
Joined: 10 Apr 2005, 17:23
Location: North Lanarkshire, UK
My Cars:
x 664

Re: STOP light on dash with low lhm fluid level

Post by Mandrake »

As Xac points out, the level is checked with the suspension on high which means that most of the oil has been pumped into the spheres, so the level in the tank is down near the bottom - there is only about 6 litres in the entire hydraulic system, at a guess I would say there is only 2 litres of that left in the tank with the suspension fully raised, and the tank can hold about 6 litres, so its only 1/3 full or less.

By design there is a good amount of leeway in the acceptable level - you can be short by a whole litre or more before you'll start to notice any problems with the warning light coming on, and even more before the function of the suspension is affected. (not that its recommended of course)

Likewise it can be overfilled by around half to one litre before you'll run into problems - the problem you'll run into in this case is that the tank will overflow messily all down the engine bay onto the ground when the suspension is fully lowered, especially if the car is parked facing up or down a slope... (ask me how I know this. :roll: )

If the level was in fact low enough for the warning light to flash on while you were driving (at normal suspension height) it would have been around 1-1.5 litres low, so its no surprise that you could pour a whole litre in and not see the disc rise off its haunches.

Checking the LHM level is a source of great bemusement and head scratching for those not familiar with it because it's checked with the suspension up which is when the level in the tank is near its minimum, the level float has a long stalk on it that reaches down near the bottom of the tank, and the total travel of the gauge is quite short, corresponding to a variation of only 0.1 - 0.2 litres. So if you're either a long way too low or too high it will be pinned to the bottom or top despite adding/removing quite a lot of oil. Rest assured that its accurate though, and when you get near to the right amount the gauge will start moving...

As Xac says a sphere may have ruptured which will consume more oil within the sphere body than normal making the level drop, but not by as much as you describe, unless a whole bunch of them went... If you haven't checked the level since buying it, its quite possible that it was simply filled to the wrong level by the previous owner - they might have filled it at normal ride height instead of fully up for example. (Pah! who needs to read owners handbooks to top up fluid levels! :mrgreen: )

Now that you've got it topped up to the correct level check it once a week and see if it changes (remember to check on level ground) and if you see a steady loss but no sign of it on the ground it could be the brake doseur valve leaking oil under the drivers carpet, but my guess is the level will be stable. You may notice a slight variation in level with temperature (oil expands with heat after all) but otherwise the level should be pretty stable from week to week. Unless you're cracking open the hydraulic system (changing spheres, disconnecting pipes etc) then there shouldn't really be any loss of oil at all, except for a very gradual apparent loss over a year or more as the spheres lose their gas pressure allowing a greater percentage of the system oil to sit in the spheres.

Finally be aware that there are two different things that trigger the hydraulic warning light on the dashboard. One is low oil level in the tank - there is a bronze disc in the bottom of the level float with a pair of contacts and a couple of wires going to it - this turns the light on if the disc rests at the bottom, which it should never do in normal circumstances as it will be pinned to the top at normal ride height with normal oil levels, and at most come down to half way with the suspension right up.

The other thing that will trigger it is low hydraulic pressure at the pressure regulator. Normal system pressure is 2400-2700 psi, if that drops below around 1000-1200 psi a pressure switch will turn the warning light on. This is what causes the light to be on for a few seconds when you start the car in the morning - after the light goes out the pressure has climbed to at least 1200 psi which means there is enough pressure for the brakes to work safely, and its typically just below the pressure where the car will start to lift.

If you lower the suspension completely for a minute or two, then put it straight into full height, its normal for the light to come on for up to 30 seconds or so as you describe, because the sudden demand for oil from the now empty and depressurised suspension will cause the system pressure to temporarily drop below 1000 psi until the pump catches up and re-pressurises the suspension. Nothing to worry about there.

Its a shame that both faults trigger the same indicator light as the severity of them is very different. If its the tank level being low causing it to flick on while driving its a "check the level next time you stop, preferably soon" type of problem, but if its due to low system pressure whilst driving its a case of "PULL OVER RIGHT NOW!", as its some sort of catastrophic system failure like a snapped auxiliary belt or a major high pressure leak :lol: (Of course even with complete failure of the front brakes the rear brakes and handbrake will still work)

In the latter case the light would just come on and stay on mind you, whereas a marginally low tank level will tend to cause the light to flicker on and off as you corner, at least at first.

LHM is dirt cheap, I carry a 1 litre bottle in the boot at all times in case of emergency, but in many years of driving Citroen's I've never had an on the road hydraulic leak or loss of main system pressure. (Oh boy am I asking for it saying something like that! :lol: )
Simon

1997 Xantia S1 3.0 V6 Auto Exclusive in Silex Grey
2016 Nissan Leaf Tekna 30kWh in White

2011 Peugeot Ion Full Electric in Silver
1977 G Special 1129cc LHD
1978 CX 2400
1997 Xantia S1 2.0i Auto VSX
1998 Xantia S2 3.0 V6 Auto Exclusive
charentejohn
Posts: 479
Joined: 16 May 2011, 14:58
Location: France
My Cars:

Re: STOP light on dash with low lhm fluid level

Post by charentejohn »

Thanks Mandrake, a very comprehensive reply an worth noting as I couldn't find any similar info by searching the forum. Unfortunately stop, dashboard and light come up a lot in postings.

I must admit when the light came on on the dual carrigeway I did say 'oh dear how worrying' or words to that effect. I then checked brakes and steering and as they still felt ok I thought it couldn't be a broken aux belt but did think they could fail at any time so was waiting for them to go. I did think the pump could be failing or similar.

I had 1L of LHM in the car which I used so have bought another to replace it, as you say pays to do so.

4 spheres were replaced before I bought the car but the other 2 could have weakened ? Also the car was serviced by a garage in recent years but not a good one I think (other posts here regarding gearbox oil etc. which could not have really been done). So they may have changed the spheres and not topped it up correctly and this has now come home to roost.
Hopefully this is the case and they were (for example) 0.7L short so adding the LHM now should cure it, I hope. I will check the level every week to see what happens, I should do a Citrobics low / high session every week anyway so will make it a routine.

I did think that set on low the system is effectively de-pressurised so the light coming on would make sense.
I do have a Lexia which I haven't got round to using yet, this may be my first reason to try it.

On reversing out with the light on I agree not ideal. Normally I wait for it to go out but that used to take a couple of seconds but lately it could be 20+ ? so hopefully it will return to the old couple of seconds. Of all warnings this one is the scariest.
You must be the change you want to see in the world - Mahatma Gandhi
Xantia HDI 90SX C3 2005 and C3 2006 both 1.4i sensodrives
User avatar
Mandrake
Posts: 8615
Joined: 10 Apr 2005, 17:23
Location: North Lanarkshire, UK
My Cars:
x 664

Re: STOP light on dash with low lhm fluid level

Post by Mandrake »

Each sphere is between 400 and 500cc in capacity, unladden at normal ride height the sphere will be about 1/4 to 1/3rd full of oil with the rest being nitrogen gas when in good condition. (The heavier the load on the car the more the gas is compressed and the more oil goes into the sphere)

If a diaphragm ruptures the sphere will completely fill with oil, which means a ruptured sphere will consume approximately 300mls of additional oil, so it would take 4 ruptured spheres to equal an apparent loss of 1.2 litres, so I doubt it's that as the suspension would be riding like a horse buggy with 4 ruptured spheres :)

When you set the height lever to low for a couple of minutes only the suspension is depressurised, (assuming the height correctors and height corrector linkages are properly adjusted) however the main pressure regulator that supplies the entire system is still at full pressure and the front brakes (which run directly from the pressure regulator via the brake doseur) will still have full pressure available to them, so the warning light will be out.

To depressurise the entire system you would need to take the additional step of opening the pressure regulator bleed screw a half turn, then the warning light will come on.

Regarding the light taking 20 seconds to go out when you first start in the morning, that's a bit long but not unreasonable. Typical time for a well running hydraulic system after standing over night is 5 - 10 seconds. It could be one of many things causing this, or a combination of things. One possibility is a main accumulator sphere that is low in gas.

The accumulator sphere bleeds away to no oil pressure over night (all oil expelled from the sphere) so the lower the starting gas pressure charge the more cc's of oil the pump has to pump back into the sphere to reach operating pressure again, thus more delay before the light will go out.
Simon

1997 Xantia S1 3.0 V6 Auto Exclusive in Silex Grey
2016 Nissan Leaf Tekna 30kWh in White

2011 Peugeot Ion Full Electric in Silver
1977 G Special 1129cc LHD
1978 CX 2400
1997 Xantia S1 2.0i Auto VSX
1998 Xantia S2 3.0 V6 Auto Exclusive
charentejohn
Posts: 479
Joined: 16 May 2011, 14:58
Location: France
My Cars:

Re: STOP light on dash with low lhm fluid level

Post by charentejohn »

I just tried the car again from a cold startup and the light went out after 10 seconds, definitely faster than recently.

Went to low then back up to normal then high, the LHM level is still the same so sounds like all is well again. I think the idea that the garage filled it in normal mode is more likely as suspension seems ok. If a sphere had gone then it will be full now so level would be the same regardless. That said the car drives fine, I will be out in it next week so will check out general feel of the car now.
You must be the change you want to see in the world - Mahatma Gandhi
Xantia HDI 90SX C3 2005 and C3 2006 both 1.4i sensodrives
User avatar
myglaren
Forum Admin Team
Posts: 25362
Joined: 02 Mar 2008, 13:30
Location: Washington
My Cars: Mazda 6
Ooops.
Previously:
2009 Honda Civic :(
C5, C5, Xantia, BX, GS, Visa.
R4, R11TXE, R14, R30TX
x 4888

Re: STOP light on dash with low lhm fluid level

Post by myglaren »

What is the tick rate of the accumulator/regulator?
charentejohn
Posts: 479
Joined: 16 May 2011, 14:58
Location: France
My Cars:

Re: STOP light on dash with low lhm fluid level

Post by charentejohn »

I have been in the garage, closed space, when the engine is running and didn't notice any ticking from the regulator, but I wasn't listening either so I wii do this tomorrow. Can't say I have ever noticed this so will be interested to see what happens.
You must be the change you want to see in the world - Mahatma Gandhi
Xantia HDI 90SX C3 2005 and C3 2006 both 1.4i sensodrives
User avatar
Mandrake
Posts: 8615
Joined: 10 Apr 2005, 17:23
Location: North Lanarkshire, UK
My Cars:
x 664

Re: STOP light on dash with low lhm fluid level

Post by Mandrake »

You'll need to crouch down and put your head near the front bumper slightly to the left of the middle of the bumper, there should be an audible click, it could be anywhere between once every 10 seconds (bad) to once every few minutes. (very good)
Simon

1997 Xantia S1 3.0 V6 Auto Exclusive in Silex Grey
2016 Nissan Leaf Tekna 30kWh in White

2011 Peugeot Ion Full Electric in Silver
1977 G Special 1129cc LHD
1978 CX 2400
1997 Xantia S1 2.0i Auto VSX
1998 Xantia S2 3.0 V6 Auto Exclusive
charentejohn
Posts: 479
Joined: 16 May 2011, 14:58
Location: France
My Cars:

Re: STOP light on dash with low lhm fluid level

Post by charentejohn »

I tried listening today when in the garage and standing over the engine, bonnet open. I am guessing this is not the best way as I couldn't hear any ticking noises, only the engine.
I will try again tomorrow with the car outside and kneeling near the front as suggested. I did drive the car and seems fine, the suspension could have improved or it could be my imagination / wishful thinking.

Unfortunately I developed a problem with my right ear a few years ago so don't hear very well in that ear at all. I only hear higher sounds, if any. Really irritating when working on cars as hearing in mono means I can't pinpoint noises so need to know where to be to hear stuff. I will report the number of ticks tomorrow.
You must be the change you want to see in the world - Mahatma Gandhi
Xantia HDI 90SX C3 2005 and C3 2006 both 1.4i sensodrives
User avatar
CitroJim
A very naughty boy
Posts: 49518
Joined: 30 Apr 2005, 23:33
Location: Paggers
My Cars: Bluebell the AX, Polly the C3 Picasso, Pix the Nissan Pixo, Propel the duathlon bike, TCR Pro the road bike and Fuji the TT bike...
x 6156
Contact:

Re: STOP light on dash with low lhm fluid level

Post by CitroJim »

Another way of listening for ticks is with a stethoscope - a long screwdriver will do - resting on the pump body. Yet another way is to hold the pipe between the pump and pressure regulator between finger and thumb and you can feel the tick as a 'pulse' in the pipe just like you can feel a pulse in your wrist...
Jim

Runner, cyclist, time triallist, duathlete, Citroen AX fan and the CCC Citroenian 'From A to Z' Columnist...
beeplumber
Posts: 14
Joined: 28 May 2012, 14:36
Location:
My Cars:

Re: STOP light on dash with low lhm fluid level

Post by beeplumber »

Just reading this post. the tick rate what doe's this indicate, this is quite quick on my HDI 110 Exculusive.
Post Reply