When I opened up the caliper to replace the disc pad, a lot of the brake fluid was drained from the caliper's chamber when I squeezed the piston back in place. I notice that there was a air valve stub on the top of the inner caliper. At the time I didn't know what it was for.
When I have put the disc/tire back to gether, I had to pump the brake about 5 minutes to get the brake fluide filling the system. I had to put in more than a bottle of new brake fluid.
The brake still feel not as sensitive as it should. I guess that there was still air in the system. As I think, I think I will have to release the air that was traped in the upper part of the caliper by pressing the valve.
My questions are:
Do I pump the brake before turning on agnition, or should it turn on the agnition first?
I think I will press the air valve down while pumping it until fluid started to come out, right?
I am sorry, but you really don`t know enough about it to risk messing with something as important as brakes. Have some one that knows exactly what there doing check your brakes. something isnt right there. KB
Changing disc brake pad and rotar is a very simple job. I have done it in many of my cars.
Some cars, the brake fluid flows back to the reservoir. This one is a relatively new car and the brake fluid is drained (leak) out from the caliper's chamber. I am pretty sure that's why Lexus put a air valve in the caliper to release the air from the upper chamber.
As I said, this is a different model where the brake fluid doens't flow back to the reservoir. I was hoping someone has the experience to confirm my thinking.
The only calipers I have ever seen that leaked fluid were 'dead' ones, no matter how new or old the car was....
There is no 'air valve' on calipers, that is a bleeder screw.
Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's - Gone to the rust pile... Canadian Off Road Trips Photos: Non members can still view! Jan/06
formatting link
(More Off Road album links at bottom of the view page)
If the caliper is leaking fluid when you compress the piston then you have defective seals and the unit should be replaced. Your description makes me think you may have opened a bleeder valve however. Where specifically did the fluid come from.
You have a lot of air in the system. I would suggest that you have the system flushed, which is a different process than using the brake pedal to bleed air. If you attempt this yourself be sure to get the proper tools and instructions for your car. There is usually a sequence in which each wheel is flushed. My suggesdtion would be to get the car to a competent mechanic and have the job done correctly.
I'm wondering if English is not the OPs first language (although he uses it better than some). This could explain some of the unusual parts of the post (I hope).
NO brake fluid should have come out at all for a simple pad replacement, unless you deliberately opened a bleeder while compressing the pistons. It is a closed system so as you compress the pistons the fluid will be forced into the reservoir on the master cylinder. If it came out somewhere else you have a major problem.
Sounds like you removed the pistons and got air in the calipers. Now you need to do a complete brake bleeding procedure on all 4 brakes to remove the air. Toyotas usually can be done without a scan tool to cycle the valves in the ABS. You just need to bleed them starting at the farthest brake first.
Don't be so arrogant man. What could go wrong? It sounds like he's already driving the car and the brakes are working, do you think they'll suddenly fail in an emergency? How?
Not when this newbie is sharing the road with the rest of us. Just because he was lucky enough to get this far doesn't guarantee something won't blow apart on the first panic stop. Somethings need so much to be right that it doesn't matter if feelings get hurt - brakes come to mind.
I'm glad that this guy is getting a little flaming. Hopefully it will motivate him to invest in either a real shop doing the work or at least finding a good, experienced mentor.
For the benefit of those who had problem visualizing what I tried to say, let me put it in chronological order and hope that it helps.
First, as a qualifier, we are talking about a 2005 Lexus GX470. Unlike most of the American cars I have seen, the caliper of this car is quite different.
Most caliper is one piece. This one has two halves.
The back half is mounted to the chassis of the car and the brake fluid tube is connected to this half.
The front half is screwed in with 4 screws to the back half.
There is a hole, with gasket, connecting the front and back chambers in the inside of the caliper. That's where the brake fluid travels from the chamber in the back to the chamber in the front to create pressure to the brake pistons.
In order to remove the brake disc and the rotor, I have to take the 4 screws and remove the front caliper from the back. When I did that, brake fluid will leak out from the hole from the chamber.
To give more space to accommodate the new disc pad I squeezed the piston and more fluid leaked through the hole from the chamber.
After reinstalling the pad, rotor and the caliper, I filled the brake fluid reservoir with a quart of new fluid and pumped the brake for 10 minutes to get fluid back in the system. The warning light system indicates everything is fine.
The brakes are working but I do feel a little sponginess. That made think which step I could be missing.
I recall that there is an air valve above the brake fluid tube in the inside of the back caliper. The valve is covered with a rubber cup like the way we have the screwed on cover to the tire stub.
So, I was guessing that, when I pumped the brake to force the fluid to refill the chamber, there may be an air pocket inside the chamber. I was thinking, maybe, I press down the air-valve while I pump the brake again, the brake fluid will force the air out from the valve.
I post the question here to look for confirmation.
I was hoping that someone have experience with this model of car and can give me some advise.
Of course, if you never touch a Lexus, it would be hard to visualize.
I hope the above have clarify some misunderstanding.
I believe you did one step too many and shouldn't have taken apart the two halves. Could be wrong, but didn't think a Saturn would be that screwed up for doing brakes, makes no real sense.... The caliper should have lifted off the rotor once the slider/mount bolts are out.
Now that you have opened it, you need to bleed the brakes.
That valve is a bleeder valve and must be loosened with a small socket wrench or box end wrench to allow the air to bleed out of the caliper as the pedal gets depressed. It then gets tightened as the pedal goes back up and then the process is repeated. A clear hose stuck on the bleeder going into a glass jar with some fluid in the bottom is sometimes used so you can see the air coming out. This usually takes two people to do and it might now need all 4 wheels bled to be safe. Especially if you let the master go empty.
Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's - Gone to the rust pile... Canadian Off Road Trips Photos: Non members can still view! Jan/06
formatting link
(More Off Road album links at bottom of the view page)
yeah, sounds like a standard 2- or 4-piston caliper to me, and I don't believe the halves are supposed to be separated... well, lesson learned I hope and the OP should bleed the brakes again and watch for leaks.
I really don't think I was able to remove the disc pad and the rotor without removing the front half of the caliper. The back caliper was solidly mounted to the chassis and the fluid hose was metal, not flexible reinforced rubber found in most cars.
Anyway, I will follow your instruction this weekend to bleed the excess air out of the chambers.
Had you looked a little harder, you'd have seen to two bolts that mount the whole caliper to the steering knuckle. There was no need to split the caliper into two pieces. Two bolts and the whole thing lifts off.
I'm sure it did.
The most basic one; knowing what you're doing.
A bleeder screw.
Press down?
Yellow pages, your best friend.
Standard fixed caliper four piston brakes. Chevrolet had them over 40 years ago.
========= ========== Mike Romain wrote in msg...... I believe you did one step too many and shouldn't have taken apart the two halves. ? ?The caliper should have lifted off the rotor once the slider/mount bolts are out. ========== ========== Nate Nagel wrotein msg:
yeah, sounds like a standard 2- or 4-piston caliper to me, and I don't believe the halves are supposed to be separated... ?well, lesson learned I hope and the OP should bleed the brakes again and watch for leaks.
nate ======= =======
what they said.....ditto.......
and.......REPLACE THE CALIPER (or caliper..sss) and bleed the system.
~:~ MarshMonster ~takes a toke.........and cranks down a bit harder on the corvette caliper case half bolts.......gonna stop this leak....i don't care WHO said they warp when you break em in half.........another toke... a sip of shroom tea.........mmmmmm........ good stuff~ ~:~ =======
is it what i'm smoke'n.......or did this dudes grammer and sentence composition get markedly better as this conversation progressed............
~:~ marsh ~takes another toke.........sips his crownroyal..... looks at the op's first post....looks at the above post....... fk it....must be the smoke, why would ANYONE..... hide the fact they could converse......... :) ~ ~:~
MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.