Kia sorento 2005 brake problems

[Garson]

Hi!I have a Kia sorento 2005 2,5l 140hp diesel and i have some problems with the brakes.
Three weeks ago i have notice that the car was going slower than usually.After 15 minutes of driving i have stop the car and check the brakes.Even if the road was almost straight wall four disc brakes were very hot.When i came home i have open all calipers and check the brake pad ,pins and cylinders.Everything seems ok so i only put some grease on the pins and put them back together.I notice that if i go 5-10 km there is no problem but if i go longer the problem come back.Last week i notice that only front left caliper (two cylinder) is blocking the wheel.When i open it i see that if i push cylinders at the same time they are stuck but if i press them separate it will move with no problem.If i push one cylinder the other one is going out.

When i check the brake pads on this caliper i saw that the one from the caliper side had less material then the other one.

There is somebody that had the same problem or that know what could cause this issue?

Thank you in advance!!

Topic

[Mike]

You did not mention any ABS or Traction Control light being on, so it is probably one or more mechanical issues.
Rear brakes can stick if the parking brake doesn’t fully release.
As the brakes heat up, it gets harder to move the car.

The reason one piston goes back in and the other pushes out is the fluid not getting released from the caliper.
This is often caused by the brake hose deteriorating inside.
To check this, pump the brake pedal a few times, then go to the caliper and open the bleeder screw. If the fluid shoots out, rather than just dripping out, you know the pressure is not releasing.
To see if the fault is inside the hose, close the bleeder screw, pump the pedal a few times and then loosen the brake line at the top of the brake hose.
If fluid shoots out, you’ll have to retighten the line and repeat the test further up, until you find a connection where the fluid just drips out.
The problem will be below that connection.
Both front and rear brake hoses can fail like that.

Did you actually used grease on the caliper pins or did you use a silicone brake lubricant?
When grease is used on rubber parts, the rubber swells and then the pins can’t slide the way they’re supposed to.
You’ll have to clean out the grease and use some brake cleaner spray to remove the grease and you’ll have to replace the swollen rubber parts.

Make sure there are no tears in the dust boots.
If they’re cracked or torn, dirt accumulates and prevents the pin from sliding.

[Garson]

Hi Bonnieman!Thank you for the reply.I don’t have any ABS or Traction Control lights on.I have order new caliper and new brake pads.My car have 260000 km so i think that brake hose could also be damaged.I will see if problem persist after i change the caliper.I have notice also that if the caliper is stuck and i stop the car,after one two hours the pressure inside the caliper goes off .

[Mike]

You’re welcome.
I hope you’re not replacing the calipers to solve the trapped pressure problem.
The caliper itself can not hold pressure unless the brake hose is bad or there is a kink in the brake line or other problem.
Trapped pressure is never a problem with the caliper.

You can test for where the pressure is being trapped (described in previous post) to know if the hose is bad.
I’ve seen this internal brake hose problem many times over the years.
When you replace the calipers, don’t allow the calipers to hang by the hoses (use a wire coat hanger or caliper hook) and make sure the hoses are not twisted.

[Garson]

Hi!I had change the caliper,brake pads and brake hose.After driving 20-30 km the front left caliper get stuck again but only for 5 minute then without any intervention from me it get loose and i could drive with no other problem.

Could it be the abs pump or the metallic pipe between abs pump and the brake hose that create this pressure in the caliper?
I assume that if the brake pump have had any problem then it would affect all four wheels right?

[Mike]

Yes, it’s possible for there to be a problem in a steel brake line or the ABS unit.

In my first reply, I described the procedure for finding exactly where the pressure is getting trapped .
That’s the only way to know exactly where the pressure is getting trapped.

Am I right in thinking that the problem has improved but not gone away completely?

Have you rechecked to be sure the problem is still brake pressure getting trapped?

If the problem is still trapped pressure, then you will have to follow the procedure I listed in my first reply.

[Garson]

Hi!Yes the trapped pressure is still the issue.The problem is that i have to drive for 10-15 minutes in order to get the wheel block.That means i have to make the pressure test on the road.
I will try to press the brake pedal many times while standing in my garage until the wheel get stuck so that i can check the pressure without driving so much.
I also notice that first the front left wheel get stuck and if i continue driving all the other wheels get stuck as well and the brake pedal get’s hard.
I will keep you posted if i somehow i manage to fix this annoying problem.

Thank’s again for your tips!

[Mike]

A strange problem indeed.
I wasn’t aware that the wheels don’t lock up when you test it in the driveway or that all 4 wheels are still locking up.

I do have a few more ideas you can try.

If the front left wheel is actually the only one to lock up, at first, it would seem to be an ABS issue, rather than the booster or master.
The ABS unit is the only part of the braking system that controls individual wheels.
The ABS solenoid may stick for the LF wheel and then the ABS unit applies the brakes to the other 3 wheels in an attempt to get all 4 wheels to turn at the same rate.

A bad brake booster or master cylinder with only 2 lines attached to it could not lock up just one wheel.

If the ABS is at fault, you might be able to isolate the problem by disconnecting the electrical connector for the ABS unit and go for a drive.

If that doesn’t work, you could bring along wrenches that fit the lines at the master cylinder and go for a drive.
When the wheels lock up, loosen the lines at the master cylinder and see if the fluid shoots out or just drips out.
If the fluid shoots out, then either the brake booster has a bad valve or the master cylinder has an internal problem.

If the booster is at fault, then disconnecting the check valve hose, while the wheels are locked, should unlock them.

[Garson]

Hi!I had manage to make some tests with my brakes and i notice that when the pressure builds up if i open either one of the two lines that goes from the master cylinder to the abs pump the pressure drops.
Is it safe to say that the master cylinder is the cause of this problem?
Regarding the booster i did not had time to check it but if it was any problem with it i wouldn’t have a hard brake pedal all the time?
If i press the brake several times with the engine stop until gets hard,when i start the engine the pedal goes down and this mean that the booster is ok right?
I will try to check the valve this weekend to see if it make any difference regarding the pressure in the brakes.

[Mike]

It’s still possible for the booster to be at fault but it’s much more likely to be the master cylinder.
I have never seen a booster fail so that it applies the brakes but it’s possible.
The only ways I can think of to check for that is to remove the check valve from the booster when the brakes are locked and see if the brakes release.
According to http://www.agcoauto.com/content/news/p2_articleid/129
“Internal valve failure may result in a lack of braking assist or brakes that do not release, depending on the failure.”

As I said, it is more likely to be the master cylinder itself.
I would install a brand new master cylinder and new fluid.
Don’t waste your time and money on a remanufactured or rebuilt master.
Reputable repair shops don’t use these for good reason; high failure rates.

The Centric Premium line of parts has always been reliable and Rockauto and Amazon typically price parts reasonably.
I always double check the part number on the manufacturer’s website.
There are different master cylinders listed for an 05 Sorento; the master is different on ABS and non-ABS models AND Manual & Automatic transmissions.

Don’t forget to bench bleed the master cylinder before installing it.
https://www.ericthecarguy.com/faq/solving-brake-problems/master-cylinder-problems

Let us know the outcome.

[Author]

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