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Discussion Starter #1
Hi,

I changed the brakes all round on my 2005 Range Rover Sport 4.2 SC RHD. All parts moving freely on the brakes, no binding. Recently purchased so don't have a good baseline on the brake feel.

After bleeding I get a solid pedal when engine is off but once the engine is running the pedal sinks slowly down to the floor. If I hit the brake like in an emergency the pedal goes hard and starts sinking slowly making it harder to stop. After some driving in the car park the pedal will become softer and have a lot of travel. Hitting the brakes at this point still causes it to go hard but normal braking pressure will allow it to brake and stop ok but I still get full travel.

I have no external fluid leaks, the pedal goes to the floor so in 20 pumps like this I would drain the fluid and this isn't happening the fluid doesn't change at all.

I manually bled the ABS module by following the directions of a technician on here of cracking the connectors on the top of the ABS module while someone held the pedal and re-tightening but that didnt help. Servo is new and holding vacuum. Thought it may be an internal master cylinder leak even though it wasn't doing it with the engine off so I have replaced that with a new one, fully bled, still the same.

I thought I should do a proper ABS bleed so got it on SDD and followed the ABS Bleed procedure where the system got me to open the bleed nipples on each wheel and pump the brakes while it did its thing. It told me to do them in the order

Rear Left. Took around 30 seconds and there was no ABS Pump or Solenoid activation. Fluid flowed whole time.
Front Left. Took around 30 seconds and there was no ABS Pump or Solenoid activation. Fluid flowed whole time.
Rear Right. Took a couple of minutes and had a lot of ABS Pump and Solenoid activation. Pedal went solid for some of this one, no fluid flow.
Front Right. Took a while and had a lot of ABS Pump and Solenoid activation. Fluid flowed whole time, sometimes slower than others.

I did this twice with the same results and Its still doing the same thing so my question is should the procedure pulse the solenoids and pump for each corner or does the above sound correct? Having replaced the servo and master cylinder I'm suspecting the ABS unit as I'm not losing fluid and its the only thing I can think would be allowing the M/C to do a full stroke at this point.

Cheers
Stot
 

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Discussion Starter #2
Rear Right. Took a couple of minutes and had a lot of ABS Pump and Solenoid activation. Pedal went solid for some of this one, no fluid flow.
Just to clarify, I had no flow when the pedal went hard during the ABS activation. At other times it would pump fluid fine.

Cheers
Stot
 

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Has anyone had the master cylinder off. Perhaps they adjusted the rod to the MC and have forced the pistons to block a passage. Just a thought. I recall years and years ago running into similar problems on some older car.
 

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Discussion Starter #4
Has anyone had the master cylinder off. Perhaps they adjusted the rod to the MC and have forced the pistons to block a passage. Just a thought. I recall years and years ago running into similar problems on some older car.
Hi,

I have fitted a new one but It doesn't appear that there is push rod adjustment on these, the push rod from the servo is one piece as is the plunger in the M/C. No adjustment on either that I could see and no mention of having to do that in the service manual.
 

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Perhaps that was only on older cars.

Why did you fit a new MC?
Did it have this problem before?

I have bled the brakes on my 09 and didn't touch the ABS. Bled just like any car I've ever worked on.
 

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Discussion Starter #6
Why did you fit a new MC?
Did it have this problem before?
The car had rusty pitedtedted brake discs when I got it so I fitted new brembo discs and pads all round.

When changing the brakes I pushed the pistons into the calipers without cracking the bleed screws and thought I might have turned a lip on the MC seal causing an internal leak. It was relatively cheap to replace so I did.

It did the same thing with old and new MC
 

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All normal for the pedal to be hard when the engine is off and then sink a bit when the engine is switched on as the vacuum brake boost kicks in but if you are loosing pedal when driving that is different and could be one of many issues.
 

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Discussion Starter #8
Having done some more research I suspect I have a stuck open dump valve on the front circuit.

Front Right. Took a while and had a lot of ABS Pump and Solenoid activation. Fluid flowed whole time, sometimes slower than others.
I believe this should have gone solid at some point like the rear circuit as the ABS closed the solenoid that restricts flow from the pedal sames as the Rear Right did but I got flow the whole time so I think that flow was back through the dump valve that should have also been closed at that point.

Best explanation of the ABS internal operation I found was here.


Found a module local cheap and will swap it out and see if that helps.

Cheers
Stot
 

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Discussion Starter #10
Well that was a fun weekend. Replaced the ABS block and still have the same issue. While I was at it I found the rear wheel hard lines has rusted through, just needed a tap to split so replaced those. Still the same.

I decided to try and isolate the Servo, M/C and ABS to see if I had air in these causing it. I made up some copper shims to drop into the brake fitting holes coming out of the ABS to blank them off, one for all 4. Started up, servo under full vacuum and solid pedal so I think I can be sure of an air free M/C and ABS unit now.

Have run the SDD bleed procedure 5 or 6 times now.

Could the flex lines cause this without visible bulges?

Cheers
Stot
 

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I had failed flex flex lines om one of my old jags. The sympton was the brake pads not releasing when off the pedal. They do fail internally with no outside hints.
 

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Discussion Starter #12
Thanks for that, looks like ill have a whole new brake system soon. :shock:

Truth is if the rear hard lines were rusting through the hoses probably need replacing anyway.

Cheers
Stot
 

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I’ve been watching this thread with some interest. Thanks Stat for posting your issue and follow ups. I’ve been chasing brake problems myself. My issue began after one of the hard pipe lines by the left rear tire rusted through. I had an independent mechanic replace a section of the line. However, afterward the pedal was never as firm as before the rupture. I bled the brakes numerous times (probably went through 3 liters of fluid bleeding both with a motive power bleeder and with a buddy depressing the pedal). The pedal would get firmer, but then later it would become “softer” or have more travel than normal. Shortly thereafter the left rear caliper start to stick. I purchased a rebuild kit disassembled, cleaned, then put the caliper back together. About a month later the rear passenger side caliper began to stick. I replaced that caliper with a rebuilt unit I got online. Then the rebuilt unit began to not disengage. When I removed the caliper I could compress the piston without too much effort—it seemed completely normal. I’ve driven it for about 600 miles since with no issues other than a spongy pedal. However I am concerned that the caliper is going to stick again.

Based on the previous post, I am going to replace the flexible hoses and see if that helps.

Because I know with my other cars (Audi’s) you have to activate the ABS pump to get any trapped air out of the pump, I went out on a slick day and got the ABS pump to activate a bunch of times. I then immediately bled the brakes. The pedal was firm—like it previously felt but then later got soft again. I’ve watched the Atlantic British brake video for the LR3/L320 and they claim the ABS module on these vehicles doesn’t need to be activated by a scan tool to get all the air out. (I have an early version of the IID tool that doesn’t have this feature).

The brake gremlin has me at a loss.





Sent from my iPhone using Tapatalk
 

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I had a rear caliper seize in the on position and replaced it with a rebuilt. Never happy with the brake feel. Several months later I noticed the rear pads worn down so I put new pads in the replaced caliper side and to my surprise found the other side to be like new. Turned out the other caliper had been seized in the off position. Replaced that caliper and now brakes feel nice. Another thing I noticed was the improvement in the brake pedal when I replaced a front hub. I think the wobbling from the worn hub bearing caused the caliper to push the brake pads apart causing a longer brake pedal. Might all have been in my head though.
 

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I think you need to get a helper so you can watch each of the hydraulic lines as they apply the brakes with the wheels off. A couple of years ago (five actually), my Land Rover dealer was doing me a favor in safety inspecting my wife's 04 Maxima. Flunked: needed a new caliper on the left rear. Bought the caliper, busted knuckles trying to get the ****ing caliper off; installed it, bled it. And while the wife was doing the pump, pump HOLD, thingy (over the years, she has gotten really good at it), I noticed that the line had bulged incredibly. Bust another knuckles and buying an additional wrench and new line: problem solved. As I examined the "bad" caliper, noted it was working perfectly.

Hydraulic line all along.

Ran into the same issue a year later on an X308. Never had to touch the ABS or MC when I replaced the Brembo Pads on my 08 RRS/SC.:tongue:
 

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Discussion Starter #16
Thanks for the encouragement. :p I did have my wife in the cab holding the brakes when I found the rusted lines. Gave them a wobble and they erupted but thats history now as I've changed all the the hoses front and back now.

Still no different. :doh: I have traced the hard rear lines back to the engine bay and there are no leaks or rusted lines now. The fronts are all in good condition too.

Its like I still have air somewhere, not sure how that would cause the hard pedal when emergency braking though.

I'm going to make up a temporary ABS delete to rule that out once and for all. If I feed the calipers direct from the master cylinder and have good brakes, likely the ABS unit is causing the issue. If not not sure what else I can try... :crybaby2:

Cheers
Stot
 

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Discussion Starter #18
Booster is holding vacuum overnight and there are no leaks in the pipework.

I tried an ABS bypass as below and had the same issue still so not the ABS block causing this.

ABS-Bypass.jpg

I cant imagine where but I think it must just be stubborn air in the system still. 8~

Cheers
Stot
 

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if the booster or master cylinder is bad you will experience the break peddle drifting all the way to the firewall due to the fluid circumventing the seals and it sounds like this is not happening... good. what are the chances of fabricating a reservoir cap that has a fitting to allow you to force new fluid into the system? this would be the same effect as wife in driver seat, but eliminate having to open/close each bleed valve and the possibility of introducing air into the system. just a thought.
 

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Discussion Starter #20
if the booster or master cylinder is bad you will experience the break peddle drifting all the way to the firewall due to the fluid circumventing the seals and it sounds like this is not happening... good. what are the chances of fabricating a reservoir cap that has a fitting to allow you to force new fluid into the system? this would be the same effect as wife in driver seat, but eliminate having to open/close each bleed valve and the possibility of introducing air into the system. just a thought.
That was my next plan. Pressure bleed the brakes in the most meticulous way I can, Master cylinder, then ABS with the help of SSD, then each line in turn. It will take a while as I only have a small pressure bleeder so something for the weekend I guess.

I still cant really figure out what scenario hitting the pedal fast would cause the pedal to go hard straight away in though. If it had been an ABS issue I could imagine an ABS solenoid blocking the pedal but I have proven its not that with the quadruple bi-pass. Otherwise hitting the pedal quickly causing the booster to lose all vacuum for some reason. Maybe not letting in atmospheric pressure in at the front somehow but its a new booster and did it with the old one too. I've even added an extra check valve right at the booster to eliminate the possibility of a vacuum hose leak. :?

Cheers
Stot
 
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