Rotors getting VERY hot

[NebRanger]

I have an ongoing problem of the rotors getting hot. Almost too hot to touch. This happens even on short trips (3-5 miles). I can only conclude that the brakes are applying too much pressure constantly. About a month ago I replaced pads, rotors, calipers, hubs, front hoses, master cylinder and a bleed job. Same problem persisting. So today I replaced the booster as it seemed to be losing vacuum, as some mornings I would have no pedal until starting the truck. During booster replacement I measured and adjusted the booster pushrod to get about .025 free play from pushrod to master cylinder. I also seemed to have very little free pedal travel and the brakes would apply very abrubtly. I have only test driven it about 4 miles but the rotors are still getting very hot, time will tell if I still have a vacuum issue.
Seems to me that the only thing I have not dug into is the RABS valve, but from what I read, it seems that most issues with that end up dealing with an inability to bleed the rear brakes, and I have not had any problem with that.
I am at a loss, and literally cant think of anything else that could be causing this.
Any help would be greatly appreciated.

 

[Dirtman]

Well too hot is kinda a vague description. Rotors should be too hot to touch after driving lol. Its completely normal for them to be over 200 degrees from regular light braking, which ummm is too hot to touch. So I'd say being able to touch them at all means they are fine...

 

[NebRanger]

Ummm...How about way hotter than any other vehicle i have, or not able to touch them for more than maybe 1 second, or hot enough they will warp rotors like they did the ones I replaced. I dont have a temp gun to get a specific temp for you. Your response is literally no help at all. Hope thats a little less vague for you... GEEZ

 

[Dirtman]

Ummm...How about way hotter than any other vehicle i have, or not able to touch them for more than maybe 1 second, or hot enough they will warp rotors like they did the ones I replaced. I dont have a temp gun to get a specific temp for you. Your response is literally no help at all. Hope thats a little less vague for you... GEEZ

K good luck.

 

[Bgunner]

The RABS valve should not have an effect on the front disk brakes since RABS stands for Rear Anti-lock Brake System.

If in the AM you have no brake pressure to me this would suggest master cylinder and not vaccum booster or a leak in a line somewhere.

My suggestion is stop by a Harbor Freight and snag a cheap Temp Gun and take a reading of the front rotors to know if one is hotter than the other and exactly how hot they are getting. This is a need to know info for us to help you online since we can not physically inspect your vehicle.

 

[Uncle Gump]

When you start to move does it feel as if the brakes are applied? Or being a manual transmission... will it roll on it's own on a small incline?

Also... just because you replaced the calipers... doesn't mean they're working properly.

another also... when you say no pedal... do you mean it won't move or falls to the floor (or travels a lot) when you hit the brakes?

 

[NebRanger]

The RABS valve should not have an effect on the front disk brakes since RABS stands for Rear Anti-lock Brake System.

If in the AM you have no brake pressure to me this would suggest master cylinder and not vaccum booster or a leak in a line somewhere.
,
My suggestion is stop by a Harbor Freight and snag a cheap Temp Gun and take a reading of the front rotors to know if one is hotter than the other and exactly how hot they are getting. This is a need to know info for us to help you online since we can not physically inspect your vehicle.

Bgunner, I will get access to a temp gun and check, also maybe a misunderstanding... I cannot press the brake pedal most mornings until engine is running, thus creating vacuum to the booster, which would lead me to believe the booster/check valve was losing vacuum. I don't see any visible issues with the vacuum hose, and hope I have corrected that issue with the new booster. I will check this in the morning, (and I guess every morning). I understand the only one that has first hand diagnosis is me, but I appreciate the input

 

[Uncle Gump]

Ummm...How about way hotter than any other vehicle i have, or not able to touch them for more than maybe 1 second, or hot enough they will warp rotors like they did the ones I replaced. I dont have a temp gun to get a specific temp for you. Your response is literally no help at all. Hope thats a little less vague for you... GEEZ

For the record... he is right. Disc brakes run pretty hot. There is no need for you to come back like you did.

Could he have said things a bit different... of course.

On the other hand... your response was pretty harsh.

Take a deep breath... there are many here willing to help you and remember... two wrong never ever make things right.

 

[NebRanger]

When you start to move does it feel as if the brakes are applied? Or being a manual transmission... will it roll on it's own on a small incline?

Also... just because you replaced the calipers... doesn't mean they're working properly.

another also... when you say no pedal... do you mean it won't move or falls to the floor (or travels a lot) when you hit the brakes?

Uncle Gump, it is a manual and on most mornings with a good frost at least one brake is stuck, (not sure which corner)
I suppose the calipers are a possibility, but the odds of both seems unlikely
I mean the pedal won't move most mornings until engine is started and creating vacuum. I did not check the check valve when replacing the booster. I figured I would just replace it since I was going to have to pull lines off the master to get it out and then re-bleed, and verify/adjust pushrod to master measurements.
Appreciate the input

 

[Bgunner]

If your vacuum issues persist after the booster replacement, here is just some info, it is common for the hard plastic vacuum lines under the dash for the heater controls to crack and leak. Just another place to watch out for that is a common issue.

 

[Uncle Gump]

Just jack it up and see what wheel is stuck... then squeeze the caliper a bit with a c-clamp and remove it and see if it spins free. It can really only be one of two thing. Bad caliper or bad slides.

Sounds like the booster or the check valve is bad also. But honestly... I see it as two separate issues. Don't think a bad booster or check valve will apply the brakes.

 

[NebRanger]

Just jack it up and see what wheel is stuck... then squeeze the caliper a bit with a c-clamp and remove it and see if it spins free. It can really only be one of two thing. Bad caliper or bad slides.

Sounds like the booster or the check valve is bad also. But honestly... I see it as two separate issues. Don't think a bad booster or check valve will apply the brakes.

I will check that on a morning that I am not leaving for work.
My latest thought with the booster was the possibility of the pushrod of the booster constantly pushing the cylinder in the master and essentially applying constant pressure, but I checked the measurements before installing the new booster, so that eliminated that thought.
I will get access to a temp gun, check temps and might as well check them on my Jeep too, to get a comparison.

Thanks for the help.

 

[Uncle Gump]

You have something hanging up on the front brakes.

I would bet money the booster check valve is bad though. Not related to the hanging up brakes... but you will probably have a good pump on your pedal in the morning.

Let us know when you get it figured out.

 

[pjtoledo]

were the old pads worn evenly?
did you replace just the calipers or calipers & brackets?
if just calipers did you clean & lube the slider pins?

how about the rear brakes, warm or cool?

jack the front up, engine off.
spin the wheels, too much resistance?
engine still off, hit brakes. wheel stops immediately?
release brakes, wheel releases immediately?

repeat with engine running.


if you think there is residual pressure in the lines try opening a bleeder. does the fluid run out or squirt out?
does the wheel turn easier with a bleeder open?

are the pads so tight in the brackets that they can't move?

for testing purposes you can disable the ABS by disconnecting the connector(s) at the front of the frame. follow the cables.

you mentioned rotors and hubs separately, 4WD? (shouldn't matter)

 

[adsm08]

two wrong never ever make things right.

But three lefts do.