Brake problems p38

Hi, After some advice. Basically when ever i brake hard the abs and red brake warning light come on. its ok when I brake lightly just lights up when braking hard. I posted a thread the other day and some people advised it could be the accumulator.

However i have had the system bled in an attempt to avoid the hefty accumulator costs and the guy who did it said there was not as much energy in the front brakes as the back, any ideas why?

I just want to be sure its the accumulator, i don't want to be £100 down with the same problem.. Please help!

danrange4 said:

Hi, the guy who did it said there was not as much energy in the front brakes as the back, any ideas why?

I just want to be sure its the accumulator, i don't want to be £100 down with the same problem.. Please help!

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YEAH ..The Accumilator has gone...

So this accumulator would cause less braking on the front than back do you think?

danrange4 said:

So this accumulator would cause less braking on the front than back do you think?

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No that would be down to the brake balance valve. How someone can say that by just bleeding the brakes i don't know. Did he put it on a rolling road?

It was because when the brake was applied on the front when bleeding the fluid came out a lot less and at a far slower pace than on the rear.

So does this put any doubt on being the accumilator now?

danrange4 said:

It was because when the brake was applied on the front when bleeding the fluid came out a lot less and at a far slower pace than on the rear.

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That maybe caused by how he bled the brakes.If you start at the bleeder farthest away from the master cylinder and work back to the closest. That would be N/S rear then O/S rear any residual pressure in the system would be released by bleeding the rear brakes. By the time he got to the front O/S then front N/S there would be no pressure in the system. That's my theory anyway. Normally there would be a greater bias towards the front brakes than the back, this is controlled by a bias valve. The only thing the accumilator does is store high pressure fluid. If the accumilator has lost part or all of it's nitrogen fill, it cannot store enough pressurised fluid, hard application of the brakes activating ABS will cause the pressure to fall below a minima lighting the warning lamps. This happens because there is not enough stored fluid to allow the ABS to modulate.

Forget the bleeding diagnosis (yes i know, tragic pun) it ain't worth XX#$. Red brake light indicates low pressure, ABS light indicates ABS might not function - and that's 99% due to low pressure. So, fair bet it IS your accumulator or, airlock or a leak. If you know there are no leaks and you're happy its been bled right (which is a bloody pain) then move on to testing your pedal feel, braking distance and ABS. Pedal spongy at first but then very hard indicates lack of pressure and the fact that you are now manually overriding in to the safety system that allows you to brake without any assistance at all. Clearly then your braking distance increases and lastly the ABS may not work. I say may not because it may only work intermittently but I challenge you to know that by the feel of the "jitter"!

Or jes fit a new accumulator like everyone's been tellin ya.

Thank for advice, makes sense why the front didn't have as much presure. Seeming like the aculimator is the way to go just wondered if there were any other possibilities? I Haven't noticed the tcs light people have mentioned with the acumilator though?

What year is yours? The TCS seems to show up more in the pre '99 ones. Might be because TC was changed a bit that year.

rasheed said:

What year is yours? The TCS seems to show up more in the pre '99 ones. Might be because TC was changed a bit that year.

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Think the system was changed from two wheel to four wheel TC that year. My 99 has four wheel TC.

Yep.

Its 1999 so guess that explains that too!

Thing is Dan, there is a way to test the pressure in the accumulator, its in RAVE. It requires a kind of pressure gauge that nobody I know actually owns so that would mean a trip to a dealer which would mean a minimum of 50 quid whereas you can shop around and get the accumulator for 80 - 90 and fit it yerself in under 10 mins. Also bear in mind the accumulator is supposed to have a life of 8 years and your's has run on for 11. So even if it hasn't completely failed its served its time and is due for relief!

Thanks for the advice, very true. Looks like its another 90 quid for island 4x4!

Good morning all. After the brakes got bled yesterday evening, i noticed when i parked the car up last night the level of brake fluid was on the max line, overnight it has crept up? Is there a logical reason for this?

danrange4 said:

Good morning all. After the brakes got bled yesterday evening, i noticed when i parked the car up last night the level of brake fluid was on the max line, overnight it has crept up? Is there a logical reason for this?

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Fluid bleeding back out of the accumilator possibly or nitrogen leaking from the accumilator into the system. Switch the ignition on and it should go down as the pump runs. Think you need to change accumilator ASAP.

Yep your right wammers switched the ignition on and it did go down to the max level.

So it is normal for the fluid to bleed back out of the accumulator then?

I was hoping to hold off until pay day as the range has raped me financially lately, do you think its safe to drive or would i risk more damage to other parts holding back for a couple of weeks?

danrange4 said:

Yep your right wammers switched the ignition on and it did go down to the max level.

So it is normal for the fluid to bleed back out of the accumulator then?

I was hoping to hold off until pay day as the range has raped me financially lately, do you think its safe to drive or would i risk more damage to other parts holding back for a couple of weeks?

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It would seem so, that is why there is excess room in the tank. If you fill it over full it will be forced out past cap. After the vehicle has been stood overnight the pump always runs when ignition is turned on to pressurise the accumilator. So yes it does bleed back over time. The accumilator has a rubber ball inside it, this is charged to 80 bar 1176 psi with nitrogen. The pump fills the accumilator against that pressure squeezing the ball and filling with a certain quantity of fluid. If your nitrogen has partially leaked out there less usable pressurised fluid. The pump is low volume so cannot keep up with fluid required by heavy braking without the reserve. If your nitrogen totally leaks out any application of the brake will start the pump and put on the warning lamps. Maybe ok for a while but if you notice lights coming on under normal light braking change accumilator straight away. Or you could end up embeded in someones rear end.

Ok, thanks for all the advice.. much appreciated