My driver side front caliper is seizing up. What could I have done to cause that. Theres also really bad scoring in the rotors on both sides but I still have about a 1/4'' of padding left. I know I need pads sometime in the future and I was gonna replace the rotors anyway, but now I might have to replace the caliper too1!! Any ideas?

 

Dude, my passenger side caliper did that to me about a week ago, it was the original caliper from 1997 so I said just replace the driver side and passenger side in one shot so i don't have to worry about the driver's failing in a short time as well. Only cure is to buy a new one. Rebuilding them is not really worth it. I also had my rotors scored very badly from the seizure, but luckily they were able to be turned and saved.

 

This really isn't an uncommon problem and you didn't do anything other then drive your truck, to cause it.

Just replace your pads, rotors and the caliper, then forget about them.

Try rockauto.com for parts. Their prices beat the crap out of my local part stores, even with shipping.

 

The 2 main causes of caliper failure are a stuck slider or a stuck piston. The slider stick from corrosion caused by chemicals put on raodways to reduce ice or simply dirt and brake dust accumulation. The caliper piston gets stuck when contamination in the form of rust and debris sits between the caliper body wall and the piston and wedges the piston into a stuck position.

While these caliper symptoms are very common, these problems are also very preventable.

I'm sure that those were not original brakes in that 1997, and there was probably not proper maintenance done when the brakes were last replaced. It is easy to just pad slap brakes and call it done. By cleaning off the sliders and re-lubing with caliper slider silicone the chances of a caliper slider sticking becomes remote as it also protects the slider from corrosion. The 2005 is probably caused by a sticking slider.

Now by contamination I'm not saying somebody put something in your brake fluid, but in essence if you don't flush your brake system every year, you did.

Brake fluid is hygroscopic, which means that it naturally absorbs water right out of the air. This water gets trapped in the brake systems causing iron and steel parts to rust discoloring your brake fluid anywhere from clear (new) to coffee or tea...I've seen almost chocolate too!

This is the reason that you have a semi-transparent brake fluid reservoir. You can easily see by the fluid color if it needs to be changed.

Anyway, the small bits of rust and such travel through the brake system under fluid movement and remain at the lowest point which is the brake caliper. When flushing the brake system yearly you will notice as the fluid clears that the bits of particles and such quit coming out of the system as well.

This process not only done yearly will prevent such contaminations, but should also be done any time there are brakes replaced or calipers and in older vehicles wheel cylinders. If there is a hydraulic brake system componenet in the ABS replaced the brake system should be flushed as well.

 

"Brake fluid is hygroscopic, which means that it naturally absorbs water right out of the air."

How does it do this in a closed system?

The only time I've ever changed brake fluid is when I've had to replace the master cylinder.

Same with power steering fluid.

The rest of your info is good.

 

They systems is not truely closed or sealed...it is just sealed as best it can be to still access the system.. If it was truely sealed then when you depress your brake pedal and the fluid is trying to go to the calipers it would hydro-lock and your brakes could never bee applied. Now don't say that the cap has that little rubber thing that expands down into the reservoir to take up the space of the extended fluid...yes to a point, but that only works until the pads start to wear and the fluid drops due to pad wear.

If you don't believe this, explain the dis-coloration and contamination commonly found in brake systems when the fluid is not regularly changed.

EDIT: Any other brake technicians or x-brake technicians that would like to back me up on this?

 

That's why there is a "full" line on the MC. Provide space for expansion. DO NOT OVER FILL.

What do you do with the bottle after you top off your MC? Throw it out, or cap it? Same thing.

I've got a truck with 473k+ miles on it and I've NEVER replaced the brake fluid. It's 21 years old with original fluid in the MC. No problems with the brake system yet.

If it gives you peace of mind, change it. It's that simple. But unless you have to change the MC or fix a broken line...........

BTW, I don't work on vehicles as a source of income. If I did, I'd change out LOTS of stuff on your vehicle that didn't really need it. :-)

 

There is an expandable rubber piece on the MC. This allows brake fluid to drop in the MC as the brake wears and still maintain isolation from the atmosphere/moisture.

The discoloration you see in old brake fluid is from heat generated by the brakes.

Agreed that old fluid should be changed regularly.

 

There is actually a small slit in the diaphragm in the reservoir cap. If you take it out and bend it around you will be able to see it. This is to allow the vacuum to deplete when the brake system replenishes due to lining wear, etc.
(NOTE: on some older vehicles, the reservoir cap does not have the slit - instead it has a series of baffles so the diaphragm can flex down to prevent vacuum).
The slit on the newer reservoir cap diaphragms will let very minimal moisture through. But still, over time, you will get some additional water content into the brake fluid.

The discoloration of the brake fluid is common, and not in itself indicative of a problem. There are additives in the brake fluid that will darken due to the heat cycling from the engine and braking. They will still perform ok. I can say this with confidence as I design & test master cylinders for a living. I have analyzed brake fluid returned from our customers that is very dark and it still passes. Discoloration can also occur from having copper in the brake system (it precipitates into the brake fluid) or from normal seal wear.

That said, brake fluid will theoretically last the life of the vehicle. This is how it is designed. But if you drive hard (lots of high speed stops, or towing) it is advisable to change the brake fluid occasionally to achieve peak performance.

For the sticking caliper - moisture in the brake fluid is very unlikely to cause the problem. The more likely issue is that the boot on the caliper sliders has cracked or fallen off, thereby allowing moisture, salt, and contamination into the slider channel. This has rusted the slider and caused it to stick.

If it were me - my first bet would be to thoroughly clean the slider with steel wool, put some caliper grease on it, replace the boot, and put it all back together. Theres a good chance this will fix your problem. If not, then look at replacing the slider pin, or the whole caliper.

good luck!

 

Let's not forget those brake hoses that can break down internally and keep a caliper piston applied when it gets hot. Try to pry the caliper piston in when it is locked up, if it does not move in, then break open the bleeder screw, if the piston now moves in then replace the hoses.

 

where does this myth come from????
The only possible explanation for a brake line (flexible or solid) trapping pressure is that somehow it gets kinked. And this should be pretty obvious.

The brake fluid pressure is exerting force outward on the tube. If there is pressure in the caliper it will push back through the tube and expand it if it is collapsed.

To my knowledge (and I've asked some of the other engineers I work with... we make automotive brakes) there is no way that a flex line can trap pressure. The problem with flex lines as they get old is the opposite... they start to swell under pressure and your brakes feel soft. That is when you need to replace them.

If you have a precise explanation of why/when a flex line can trap pressure, please let me know. Do not just reply with "well, one time my cousin Billy Bob Joe had a dragging caliper and he replaced the flex line and that fixed it".
Thanks

 

On the brake line ''myth'',what happens is the brake line will act like a backflow valve.It will allow fluid in one way,and not back out,you are applying ALOT more pressure to the calipers than what it takes to release.There is no pressure on releasing the pedal,the pressure is generated when you apply the brakes,thus causing fluid to enter the caliper or wheel cyl,when you release the pedal,the fluid flows backwards,not under pressure,The lines will get swollen inside ,and not allow the fluid to flow back out.Also,sometimes the line will start to deteriate inside,,thus causing the same problem.I have been ASE certified in brakes and front-ends for 13 years,and been working on brake systems since 1981,I have seen a brake line collapse inside and/or get swollen inside many times,causing the same symptoms as a frozen caliper,When I say frozen,I don't mean from cold,I mean from contanminates in the fluid/caliper.Also,there are some manufactures that make phenolic pistons,which also will get swollen from contanimates in the fluid and cause the caliper to stop working.So,actually,it is not a ''myth'',it is a fact.The biggest problem i see here is you are talking to engineers,get out in the field and see for yourself,I am NOT by any means bashing engineers,but they can do it on paper really well,but, allmost anyone on this forum can agree upon this statement,they do not have the field experience,although it works on paper,does not mean it works in the real world.I am not trying to make you or anyone else mad on here,but that is the way it is.

 

Question for you guys. My old truck was 15yrs old when I finally got rid of it. I never flushed the brake fluid and I went through 3 or 4 calipers possibly cause of not changing the fluid who knows. But I want to take better care of the this truck, how does a person flush the brake fluid with ABS? Is just bleeding the brakes the conventional way until you seen fresh fluid come out good enough or does that not get enough of the old fluid out of the ABS?

BTW my wifes 06 Honda Accord says to have the fluid flushed every 3 years regardless of milage but I didn't info in the trucks owners manual.

 

ABS is just sensors,so yes,the regular way,get the fluid out of master cyl,fill it up with clean fluid,and bleed the brakes till fresh fluid is comming out,make sure you check the fluid level often while you are flushing the system.

 

isn't there usually the abs block that actually does the brake modulation and has brake fluid in there?