STOP and low hydraulic pressure lights flashing

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Jugostran
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STOP and low hydraulic pressure lights flashing

Post by Jugostran »

Hello, hope everyone's doing great.
Okay, so I was just talking with someone about issues I am having with my BX's suspension and steering. They pointed out that the two lights I am seeing when going into sharper hairpins and when the car is at max height means the hydraulic system is below 70 bar (whereas it should be at 175). This coincides with fast tick times, long hiss times between ticks and hard suspension and steering. What could be causing the car to lose more than 100 bar of pressure?
Many thanks for any answers or suggestions on how to rectify this.
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David
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Re: STOP and low hydraulic pressure lights flashing

Post by David »

This might be obvious, but have you checked the LHM fluid level? If the lights flicker when it's going around corners, with the suspension at maximum height, then I'd suspect that's the issue.

Check the level first and go from there.

Expanding on that, if you've got low fluid level, you'll probably have a leak somewhere, so it'd be a good idea to find and fix it. If a high pressure pipe bursts while you're driving, then you can quickly lose the brakes.

Hope that helps.
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Jugostran
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Re: STOP and low hydraulic pressure lights flashing

Post by Jugostran »

David wrote: Sun Apr 23, 2023 10:02 am This might be obvious, but have you checked the LHM fluid level? If the lights flicker when it's going around corners, with the suspension at maximum height, then I'd suspect that's the issue.

Check the level first and go from there.

Expanding on that, if you've got low fluid level, you'll probably have a leak somewhere, so it'd be a good idea to find and fix it. If a high pressure pipe bursts while you're driving, then you can quickly lose the brakes.

Hope that helps.
It is of great help in starting the diagnostics, that's for sure.
I have checked the level, and refilling it seems to have improved things. However, I still get very long hiss times. Other than seepage from around the seal on the LHM reservoir, another point of leakage seems to be from both the pressure regulator and flow divider block. I did order some rubber grommets to address this, however the long hiss times lead me to believe something else is wrong here as well. A friend has already pinned down that it could be either one of those components, but I am not sure which.
The symptoms of hard steering and often hard suspension still appear intermittently.
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Jaba
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Re: STOP and low hydraulic pressure lights flashing

Post by Jaba »

I am wondering if you have cleaned the LHM filters in the reservoir to ensure there is enough flow to maintain the system pressure.
Those leaks from the flow divider will not affect its operation. The leaks are curable with new orings but it is a fiddly job to do.
Also have you checked the accumulator pressure using the sit on the boot method?
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Re: STOP and low hydraulic pressure lights flashing

Post by Jugostran »

Jaba wrote: Tue Apr 25, 2023 6:43 pm I am wondering if you have cleaned the LHM filters in the reservoir to ensure there is enough flow to maintain the system pressure.
Those leaks from the flow divider will not affect its operation. The leaks are curable with new orings but it is a fiddly job to do.
Also have you checked the accumulator pressure using the sit on the boot method?
I cleaned the filter inside of the LHM reservoir back when it catastrophically failed. That was only half a year ago.
I am not aware of any other filters in the system.
And yes, I have tried the sit on boot method. It works like a charm.
I often find it funny how I can lower the car completely and then turn it off, before it proceeds to raise to standard height.
So, I am at a bit of a loss.
The lights flashing were cured by adding more LHM, but long hiss times are still present even when driving. Also, even though my struts are fine, it often goes into this state of extreme stiffness, while sometimes it is really soft.
All of this is quite confusing as I don't even know where to start my diagnostics.
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Re: STOP and low hydraulic pressure lights flashing

Post by saintjamesy89 »

Interesting you mentioned the struts are sometimes very stiff, I have this on my GT sometimes. IIRC a worn strut can leak internally and so at the extreme perhaps this could be affecting the overall system pressure? I'm not knowledgeable enough to say if this is true or not. How does your pump sound? Worn/weak pumps are a thing.

Other things I'd check is the wiring for the LHM reservoir, I don't know if BX's have a pressure sensor in their mechanical system - but if they did, that could also be checked.
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Jugostran
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Re: STOP and low hydraulic pressure lights flashing

Post by Jugostran »

saintjamesy89 wrote: Mon May 01, 2023 9:44 am Interesting you mentioned the struts are sometimes very stiff, I have this on my GT sometimes. IIRC a worn strut can leak internally and so at the extreme perhaps this could be affecting the overall system pressure? I'm not knowledgeable enough to say if this is true or not. How does your pump sound? Worn/weak pumps are a thing.

Other things I'd check is the wiring for the LHM reservoir, I don't know if BX's have a pressure sensor in their mechanical system - but if they did, that could also be checked.
That sounds like an interesting theory. I am replacing both the struts and strut tops from a parts car, so I'll see if that's the issue.
My pump sounds fine, but there is a grinding noise when the pressure regulator kicks in. Putting my finger to the flow divider above the pressure regulator confirms my suspicions - it is fubar. By that I mean it is the source of the grinding noise.
Also, refilling the system made the stop and low hydraulic pressure lights go away, but I still get fast ticks and the such. I doubt it's the pressure regulator as it has been replaced and is known good.
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Re: STOP and low hydraulic pressure lights flashing

Post by Jaba »

The pump is an easy thing to change so that might be your best option to change next as these can make a lot of noise when faulty.
Have you disconnected each of the return hoses at the reservoir to check for excessive return with the engine running.
Another sign of a weak pump is when doing a 3 point turn with cold LHM the power assistance comes and goes as the steering takes a lot fluid and pressure as the wheels are turned.
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Jugostran
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Re: STOP and low hydraulic pressure lights flashing

Post by Jugostran »

Jaba wrote: Mon May 08, 2023 11:18 pm The pump is an easy thing to change so that might be your best option to change next as these can make a lot of noise when faulty.
Have you disconnected each of the return hoses at the reservoir to check for excessive return with the engine running.
Another sign of a weak pump is when doing a 3 point turn with cold LHM the power assistance comes and goes as the steering takes a lot fluid and pressure as the wheels are turned.
I haven't disconnected the returns, not sure which two are the returns. However, when manouvering with cold LHM at low speeds, the power steering can feel quite heavy.
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