Hello Roverers,

These past two weeks I've been having some braking issues that are getting worse by the day with my 2002 LR Discovery S2 SE; basically I have no pressure on the pedal, so I have to pump it repeatedly to attempt braking, a bit easy when under 30 mph, but harder when above it. If I stomp real hard when the pedal is at the bottom, it will brake more 'till truck stops, and tends to swirl a bit to the left, but it still does not brake properly, so definitely there's an issue there.

When pumping it, I can hear the "hissing", which is now noticeable since I'm aware of the braking issue, but don't remember if the hissing existed before.

When I hop on the truck early in the morning, after it sat parked overnight, the pedal is kinda hard, but as soon as I crank it up, it gives in and I can press the brake to shift out of park. As soon as I start driving the pressure dies out, and is just hard to brake as the drive progresses, so I drive slowly, like if I'm driving Miss Daisy.

There are a couple of issues to disclose in order for you guys to have a better pic. Since I bought the truck (over 5 yrs ago), the "Three Amigos" have been on, and I have not bothered to solve it yet, since it did not interfere with the braking situation so far, or so I thought, but I know I need to fix this sooner than later. Also, the "Intake Manifold Brake Servo Vacuum" (black thingy with red lock) broke off a couple yrs back and haven't replaced it; instead, I followed a temp suggestion to silicone the tube to the manifold while I fix the issue, but it became a permanent solution waiting to be fixed (I checked it, and tube still in place and holding, so it seems no air is coming out from there for now. Recently some repairs were done in the front suspension, and the Frt Lft ABS Sensor got broken, making the BRAKE light to come on since; I already bought the part and looking to replace it soon, but I had no issues then or the days following the event.

Took it to my local Firestone a couple days ago, and they insist is the ABS Module, that I needed to have it checked at a LR dealer, and considered all other components were OK (I think they just didn't want to mess with it for lack of knowledge, and opted to send me to a dealer for liability reasons).

Two days later I went to a local shop nearby, and requested to bleed the system, they did and said that only the rear right had a bit of air in it; they suggest I replace the Booster to solve my issue, and when replacing it, they would check if necessary to replace the Master Cylinder if it shows sign of leakage there, other than that, they don't see any other reason for not having brakes. They checked the fluid, and topped it off, but it wasn't missing enough to become an issue, also checked for fluid leakage, but found none.

I will be taking it to my regular mechanic this weekend, but wanted to share it with you guys and try to get some input to go over with him.

Your feedback will be greatly appreciated, thanks in advance. ;-]#

 

You're on the right track with not running to fix the ABS. It's my understanding that failure shouldn't cause a loss of overall pressure.

Had this bookmarked for a different project a while back: ( I think this process should apply to a rover system)

https://axleaddict.com/auto-repair/B...-Booster-Check

If the booster vacuum hose and fittings are in good shape, it's time to move to the brake booster itself. A common and simple way to test the brake booster is by using the brake pedal.

1. Sit behind the steering wheel, set the transmission to park (automatic) or neutral (manual), set the emergency brakes, and start the engine. Let it idle for two minutes and then shut if off.
2. Pump the brake pedal at normal foot pressure four times and hold your foot on the pedal pressing down slightly on it.
3. Start the engine. As you start the engine, you should feel the brake pedal moving downward slightly, about an inch or less. Otherwise, you don't have enough vacuum in the brake booster. To locate the fault, do the Engine Vacuum and Brake Booster tests described in the following sections.
4. With the engine still idling, remove your foot from the brake pedal and turn off the engine.
5. Depress the brake pedal (using normal foot pressure) four times. If you notice the pedal rising after the second or third you depress it, the booster is more likely holding vacuum. Otherwise, a vacuum leak is affecting booster performance. To locate the problematic area, test engine vacuum and brake booster performance using a vacuum gauge and a handheld vacuum pump as described in the next sections.
6. Start the engine and let it idle.
7. Now, push down the brake pedal and turn off the engine, but hold the pedal depressed for about 30 seconds after shutting off the engine.

The pedal should hold its position. If not, there's a leak in the brake booster, valve, vacuum hose, or intake manifold. Check the vacuum hose, booster check valve, engine vacuum, and brake booster as described in the following sections.

 

Sounds like a brake booster

 

Does the pedal drop to the floor slowly/quickly at a stop light? If so, replace the booster as above. If not, check calipers for movement or stickiness. I know a lot of D2 owners complain that their brake pedal has to be pumped to firm up when cold, but not as much once it gets warm. I've yet to find a fix for that. But your issue sounds like the master is toast. They're not hard to replace, but I'd try my hardest to find an OEM NEW unit. Not a recon or used one.

 

 

THANKS STB616 FOR THE INFO.

 

thanks twix!

 

Thanks Best4x4, I'll be sure to search Ebay for it.

 

..:: UPDATE ::..

In today's commute back home, it felt like the pedal was holding a bit more pressure when short pumping it repeatedly when needed to brake, instead of pumping it by pressing the pedal all the way to the bottom repeatedly; in any case, it still sunk to the bottom when pressing down when at full stop, so I had to keep cruising slowly, while keeping a good distance and vigilant to avoid sudden stops.

I'm thinking to first replace the "Intake Manifold Brake Servo Vacuum" (black thingy with red lock) that broke off a couple yrs back and is still holding in place with silicone, along with the hose that connects it to the Booster, while I determine which part needs to be replace, if the MASTER CYLINDER or the BOOSTER?

I'll check tomorrow for any leakage, or signs of between the Cylinder and the Booster.

Thank you all for your input, greatly appreciated. ;-]#

 

i recently went through something similar to this with a fellow forum member. it really sounds like a vacuum leak in the booster to me, along with a leaking master cylinder or possibly a brake line somewhere further downstream.
you should be able to narrow down the vacuum leak by starting the engine and listening carefully while an assistant presses on the brake pedal. there's a seal between the master cylinder assembly and the brake booster that can lose its effectiveness if brake fluid starts to corrode the outer surface of the booster. there's also the vacuum line from the intake manifold, as you have noted. and don't forget the port where the vacuum line attaches to the booster itself.
after addressing the vacuum leak (and potentially fixing the another problem if your master cylinder is leaking and you replace that at the same time, which i would advise), your pedal should no longer go to the floor once your system has been bled. if it still does, it's time to start checking your calipers and lines for leaks.