Brake problem
#11
11-01-2017 | 04:10 AM
Thread Starter
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4wd Low
Joined: Oct 2017
Posts: 13
Likes: 0
Hi Matt,
Thanks for the assistance. I am not sure what you mean in item 2: "You will need to reset the switch that activates the lights"
I had the booster off the car and all seemed OK there. Not sure why a booster would allow a pedal to slowly sink to the floor on brake application,. To be very hard and have no servo assistance if the diaphragm was damaged or the servo was leaking vacuum yes. But as the brake pedal is more or less directly mechanically linked to the MC through the servo then I am unsure how a servo fault would allow the pedal to sink, especially as all brake bleeding and testing is done without the engine running and hence the servo un-pressurized.
Maybe someone can assist me to understand this one Matt.
Anyway thanks all input is greatly appreciated.
incidentally I found the RAV modulator and manual bleed procedures. Now there's a somewhat vague set of instructions for getting air out of a LR S2 braking system
Steve.
Hey ho, back funder the car for me
Thanks for the assistance. I am not sure what you mean in item 2: "You will need to reset the switch that activates the lights"
I had the booster off the car and all seemed OK there. Not sure why a booster would allow a pedal to slowly sink to the floor on brake application,. To be very hard and have no servo assistance if the diaphragm was damaged or the servo was leaking vacuum yes. But as the brake pedal is more or less directly mechanically linked to the MC through the servo then I am unsure how a servo fault would allow the pedal to sink, especially as all brake bleeding and testing is done without the engine running and hence the servo un-pressurized.
Maybe someone can assist me to understand this one Matt.
Anyway thanks all input is greatly appreciated.
incidentally I found the RAV modulator and manual bleed procedures. Now there's a somewhat vague set of instructions for getting air out of a LR S2 braking system
Steve.
Hey ho, back funder the car for me
#12
11-01-2017 | 04:29 AM
Camel Trophy
Joined: Oct 2016
Posts: 4,703
Likes: 1,282
From: Michigan
Yes, a bad booster would have nothing to do with your loss of fluid (unless MC was leaking into it, but you've eliminated that suspect).
A couple post back, I thought you mentioned finding a leak underneath the vehicle? You need to pursue this issue and see if it is brake fluid. In your initial post, you mentioned being low on brake fluid on two separate occasions...so, this fliud went somewhere...it doesn't just disappear. Start the vehicle and have someone pump the pedal until firm...and while you are underneath watching...have them push down on the pedal with all their super-human might. If there's a leak...it should show itself.
Good luck,
Brian.
A couple post back, I thought you mentioned finding a leak underneath the vehicle? You need to pursue this issue and see if it is brake fluid. In your initial post, you mentioned being low on brake fluid on two separate occasions...so, this fliud went somewhere...it doesn't just disappear. Start the vehicle and have someone pump the pedal until firm...and while you are underneath watching...have them push down on the pedal with all their super-human might. If there's a leak...it should show itself.
Good luck,
Brian.
#13
11-01-2017 | 07:09 AM
Winching
Joined: Sep 2010
Posts: 745
Likes: 141
From: Fairfield County, CT
Here is a picture of the switch I am talking about:
Brake Light Switch For Discovery II And Range Rover P38
It is near the pedal. Page 890 of the RAVE.
If the booster/servo {#8 on page 857} has a vacuum leak, the pedal will eventually go all the way to the floor without any real real braking action being available to you. You will then be in "FRED FLINSTONE MODE" where the only braking action you get will come from pushing very hard on the pedal.
You may also need to replace this part as well:
Hose Brake Servo To Intake Manifold W/ Sec. Air Injec. (Genuine Part # SQB103301 ) - Land Rover hoses from Atlantic British
Leaking vacuum lines in Rovers are not uncommon.
Brake Light Switch For Discovery II And Range Rover P38
It is near the pedal. Page 890 of the RAVE.
If the booster/servo {#8 on page 857} has a vacuum leak, the pedal will eventually go all the way to the floor without any real real braking action being available to you. You will then be in "FRED FLINSTONE MODE" where the only braking action you get will come from pushing very hard on the pedal.
You may also need to replace this part as well:
Hose Brake Servo To Intake Manifold W/ Sec. Air Injec. (Genuine Part # SQB103301 ) - Land Rover hoses from Atlantic British
Leaking vacuum lines in Rovers are not uncommon.
#14
11-01-2017 | 12:20 PM
Recovery Vehicle
Joined: Oct 2013
Posts: 962
Likes: 87
From: Southern OR
Thanks guys for the info so far.
Well, I pulled the MC and servo off the car this morning, bit easier than i expected, especially the brake pedal retaining clip. The MC was wet around the fixing holes, but seemed dry towards the rear where it is inside the servo. The servo had no fluid apparent in the bottom and looked perfectly dry and serviceable, so thats gone back on the car. If the MC was leaking then it would seem at this stage the fluid entering the booster was being pulled straight into vacuum line and hence the engine as you advised Brian.
The car is now up on axle stands with the wheels off ready for bleeding when the new MC comes. I have had a good look around the lines and wheel cylinders/calipers and all seems to be dry. However as I jacked the back of the car up a dribble of fluid exited from the near side chassis member drain hole roughly mid way down the car opposite the rear of the front passenger door. Nothing unusual I thought, she stands outside. But it looked a bit like brake fluid and tasted very bitter. The two rear brake lines run along the top of this chassis members and again I can see no obvious leakage.
Maybe I am leading myself down a rabbit hole here?
Well, I pulled the MC and servo off the car this morning, bit easier than i expected, especially the brake pedal retaining clip. The MC was wet around the fixing holes, but seemed dry towards the rear where it is inside the servo. The servo had no fluid apparent in the bottom and looked perfectly dry and serviceable, so thats gone back on the car. If the MC was leaking then it would seem at this stage the fluid entering the booster was being pulled straight into vacuum line and hence the engine as you advised Brian.
The car is now up on axle stands with the wheels off ready for bleeding when the new MC comes. I have had a good look around the lines and wheel cylinders/calipers and all seems to be dry. However as I jacked the back of the car up a dribble of fluid exited from the near side chassis member drain hole roughly mid way down the car opposite the rear of the front passenger door. Nothing unusual I thought, she stands outside. But it looked a bit like brake fluid and tasted very bitter. The two rear brake lines run along the top of this chassis members and again I can see no obvious leakage.
Maybe I am leading myself down a rabbit hole here?
I think you need to go down in that hole?
#15
11-01-2017 | 12:58 PM
Thread Starter
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4wd Low
Joined: Oct 2017
Posts: 13
Likes: 0
Hi Guys.
Well you were all right in your thoughts and I guess the real clue was as you said Brian the loss of fluid. My thoughts that the MC was faulty dumping fluid into the booster was incorrect and pulling the booster and finding no fluid in it confirmed it.
Once the system was back together and a firm pedal gained I did just what you advised. I ran the engine to gain servo boost and pressed down on the pedal hard until it sunk to the floor a few times. Confirming that fluid had been expelled from the MC reservoir, I got under the car again and this time the fluid leak was much more apparent, from the nearside chassis member top just as it goes towards the rear wheel.
The rear brake lines run on top of the chassis member down the car, probably to protect them from enthusiastic off-road damage. However it does subject them to wet road mud that sits on the chassis top and rusts them out as this had done, so not such a good idea. Anyway out with the old and in with new copper pipes, manually bleed the calipers, bleed the modulator in line with RAV instructions and a further power bleed on the calipers again, returned the pedal to rock hard status. Albeit not as hard when the booster was pressurized but the brakes are now working fine with no fliud loss.
I was very interested in Matt's comments regarding the ratchet resetting of the brake switch. I have never come across that sort before and found this in another thread: "......the switch is auto adjusting. When you disconnected the old booster the pedal returned father because it was not retained anymore. This compresses the brake switch more than before. All you have to do is get under there, push down the pedal, grab the push button on the switch and pull it all the way out. You'll feel it ratchet out, then just release the pedal and it will push it back in to the proper adjusted distance.
Thanks to you all, your help was invaluable and we are now back and playing again
))
Steve
Well you were all right in your thoughts and I guess the real clue was as you said Brian the loss of fluid. My thoughts that the MC was faulty dumping fluid into the booster was incorrect and pulling the booster and finding no fluid in it confirmed it.
Once the system was back together and a firm pedal gained I did just what you advised. I ran the engine to gain servo boost and pressed down on the pedal hard until it sunk to the floor a few times. Confirming that fluid had been expelled from the MC reservoir, I got under the car again and this time the fluid leak was much more apparent, from the nearside chassis member top just as it goes towards the rear wheel.
The rear brake lines run on top of the chassis member down the car, probably to protect them from enthusiastic off-road damage. However it does subject them to wet road mud that sits on the chassis top and rusts them out as this had done, so not such a good idea. Anyway out with the old and in with new copper pipes, manually bleed the calipers, bleed the modulator in line with RAV instructions and a further power bleed on the calipers again, returned the pedal to rock hard status. Albeit not as hard when the booster was pressurized but the brakes are now working fine with no fliud loss.
I was very interested in Matt's comments regarding the ratchet resetting of the brake switch. I have never come across that sort before and found this in another thread: "......the switch is auto adjusting. When you disconnected the old booster the pedal returned father because it was not retained anymore. This compresses the brake switch more than before. All you have to do is get under there, push down the pedal, grab the push button on the switch and pull it all the way out. You'll feel it ratchet out, then just release the pedal and it will push it back in to the proper adjusted distance.
Thanks to you all, your help was invaluable and we are now back and playing again
))Steve
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