Poor brake performance on a 2002 jeep liberty

[Chris Perigny]

Hello folks!
I own a 02 jeep liberty sport v6. Somehow, it feels like I need to press the pedal further to stop the vehicle. Here is what I did so far:

– Bleed the entire brake lines
– Replaced the front rotors and pads.
– Checked the calipers and rear wheel cylinders for leaks (none found)
– Adjusted the rear drums shoes.

Power brake booster is airtight. I lifted the rear end and put the transmission in drive and applied the brakes. The rear wheels slowly stopped and if I release the pedal, the wheels start to spin again, so I am sure something is wrong here.
If I depress the pedal, it will stop the car but like I said it feels I need to go further down and apply more pressure to stop the car.

Also, I am unable to lock the wheel if I drive…
My next step is to replace the Master Cylinder.

What else could it be?

Topic

[Bobby]

It could be an internal master cylinder leak, or the master leaking into the brake booster. This doesn’t always show external fluid signs. I would be very cautious and try not to drive this vehicle until you find the issue.

How is your brake fluid level?

Try this:

With the vehicle off, press the brake pedal several times. The brakes should become noticeably firmer (Doing this will cause you to use up any residual vacuum assist in the booster). If the pedal firms up (Very hard to press), then it’s possible that the issue is with the brake booster and not with the master cylinder.

If the master cylinder is bad, the pedal will sink even when the vehicle is off, and the vac is gone.

if the pedal firms up and doesn’t sink with the booster off, the master cylinder probably isn’t leaking internally.

Hope this helps you troubleshoot.

[Chris Perigny]

Hello Boodaddy!
Fluid level is OK, so this means no external leak. When the engine is off, the pedal does get noticeably firmer.

The pedal does not sink when the booster is off. If there is an internal leak in the master cylinder only on the second stage (rear wheels on the liberty) could that cause such problems?

At first, I tought of bad rear wheels cylinder (frozen) but if the rear wheels stops and restart, it means the Wheel cylinders are not stuck.

Could it be the flexible brake lines?? If so, how can I test them?

[Lorrin Barth]

I bought some semi-expensive ceramic name brand brake pads for my car. Well, it was now like braking was more of a suggestion than a command. I’d find myself applying the brakes a block ahead of a stop sign.

If you dip into the more expensive pads available you can obtain some with real bite. However, some of these can be noisy and eat rotors. OEM is usually a good pad if you can handle the price.

So, anyway, I read you have replaced your brake pads in an effort to solve the problem. Did you use the same pads as before?

[Cameron]

[quote=”Trakkat78″ post=107245]
Fluid level is OK, so this means no external leak. When the engine is off, the pedal does get noticeably firmer.

The pedal does not sink when the booster is off. If there is an internal leak in the master cylinder only on the second stage (rear wheels on the liberty) could that cause such problems?

At first, I thought of bad rear wheels cylinder (frozen) but if the rear wheels stops and restart, it means the Wheel cylinders are not stuck.

Could it be the flexible brake lines?? If so, how can I test them?[/quote]

Sounds to me from what you have said that, at least in the lines for the rear brakes, you still have quite a bit of air in the system and you are compressing air instead of pushing fluid. Even if they have just been bled there might still be a pin size hole somewhere that is allowing air in as well as a small fluid leak. Bleeding the rear brakes again should show up any air bubbles in the fluid provided you have a clear tube attached to the bleeder screws so you can see the fluid and air bubbles as the fluid is pumped out of the lines and calipers.

If you still have the original brake hoses on the car they will also have deteriorated substantially inside restricting the flow of fluid each way. Once removed deterioration will be evident inside the hoses.

If you find air bubbles in the brake fluid again so soon after you bled the system, I would get the vehicle on a lift and carefully check all the brake lines visible under the Jeep for any signs of tiny fluid leaks.

In any event, definitely change all the flexible brake hoses ( F and R) if any of them are more than 6 years old.

[Author]

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