Topic: master cylinder

[82 HiLux]

Hey guys Im having brake problems. 
When Im going and I push on the brakes they go CLICK as soon as the brakes start working.  As soon as there is drag on them and the truck begins to slow they click. 
Also, after driving any distance (could be 10 feet or 10000 feet) the brake petal pushes in kinda far.  If I am driving and go to hit the brakes, I often need to push it and then push it again and hold it down like normal.  I have to pump it once before actually using the brakes to get them to work better. 
My dad and I think this is the master cylinder causing the problem.  I think the clicking is the 25+ year old calipers. 
Pads are relatively new.  Rotors are pretty well toast.

How helpful is turning the rotors? Right front rotor has grooves in it 

Thanks for the help

[jimbo74]

turning the rotors sucks, they will warp faster than solid untouched rotors... with as cheap as rotors are these days, and upgrades available too, there is no reason not to replace them.... the rotors still may be turnable, but if you've already grooved them, they are probably trash, either groves too deep past usuable specs


sure the click has anything to do with it? i would think the click is the little switch for the brakelights or a loose pivot bolt on the pedal of some sort

as far as the MC, it could be that, especially if pumping makesit better... how is the fluid level? and when was the last time the fluid was flushed? fluid is very hygroscopic and it will pull water out of the air and that water will contaminate the brake system... it is said that flushing the system should be done a minimum of every 2 years

[79coyotefrg]

if the rotors  are grooved  best thing is to replace the rotors,

where is this clicking coming from??  does it sound like its coming from under the dash??  = pedal/spring/pushrod/ booster.

from  outside??  front? or rear??   could be a broke spring in the rear brakes

pumping  is a sign  you have air in the system
needs to be bled

also  if you have a lift  the rod  on your rear axle that goes up to the frame  needs to be  removed from the axle and tied  to the frame

[Yota Tony]

pumping  is a sign  you have air in the system
needs to be bled

Not always true. I bled my brakes 4-5 times on my old truck and couldn't get the pedal to feel any better.
Replaced the master cylinder and it was a lot better then before.

The clunking could be any number of things so you'll need to clear that up for us.
Do the calipers look bad? If so you might want to think about replacing them.

[jimbo74]

Not always true. I bled my brakes 4-5 times on my old truck and couldn't get the pedal to feel any better.
Replaced the master cylinder and it was a lot better then before.

no he is right, pumping is air i nthe system... the fact that it was a bas mc was that the bad mc was allowing air into the system that otherwise wouldnt have gotten in..... line can easily cavitate bubbles as well, bleeding several times may not get it out... you have to bleed the line itself...

[Tallchevy]

One or both of your rotors can be wrapped enough that while driving, the rotors will push on the brake pads causing the caliper pistons to push back. This causes a larger gap between the pads & rotors, which causes you to pump the brake. I had this problem on a 77 Dodge 4x4. I bought the truck that way & it was scary to drive but it didn't take long to figure out. Sometimes you can feel the pulsation in the brake pedal while applying the brakes. Take off the front wheels & step on the brake. Then try to rotate the hubs by hand & see what happens. If your rotors have deep grooves already, buy a new set & have them turned so they're true. Alot of people think that a new rotor is true but some still have what is called runout. The runout is what you want to get rid of.   

[fordh8r]

One or both of your rotors can be wrapped enough that while driving, the rotors will push on the brake pads causing the caliper pistons to push back. This causes a larger gap between the pads & rotors, which causes you to pump the brake. I had this problem on a 77 Dodge 4x4. I bought the truck that way & it was scary to drive but it didn't take long to figure out. Sometimes you can feel the pulsation in the brake pedal while applying the brakes. Take off the front wheels & step on the brake. Then try to rotate the hubs by hand & see what happens. If your rotors have deep grooves already, buy a new set & have them turned so they're true. Alot of people think that a new rotor is true but some still have what is called runout. The runout is what you want to get rid of.   

This is true, the only thing I have to add to this that offers similar results is possibly misadjusted wheel bearings which when the rotors sag they will force the pads apart increasing pedal travel during application. When the pedal is applied there is enough force to straighten the rotor for the pads to bottom out and then get pedal pressure. Even the slightest amount of bearing play can add to any unwanted pedal travel since the brake pads move ever so slightly when operating normally.

[82 HiLux [OP]]

the sound is not the brake lights i know that.  It sounds like a loose bolt almost but it sounds more like its coming from under the truck towards the front.  as for the pumping, its not really doing anything now.  they just sort of suck in general.  i get stopped okay, but i have to use a lot of brake force.  not really A LOT A LOT but more than I should.  Ive driven other peoples old trucks and new ones with bigger tires and im sure my brakes have seen better days. 

I know about the LSPV and it was taken care of a long time ago.  Its easily adjustable now too!

Im too tired to go out and examine them right now, ill get back on this later.
thanks for all the help everybody I appreciate it 

[Tallchevy]

You said the pads are new. Did you replace them  or did someone else. The clicking sound could be from warpped rotors & not installing the brake retaining hardware properly. The pads will move up & down causing the click when the rotor grabs the pad.     again.

[82 HiLux [OP]]

I put them on.  I would never take my truck into a shop to have something done to it.  Except smog.

The clicking sound could be from warpped rotors & not installing the brake retaining hardware properly. The pads will move up & down causing the click when the rotor grabs the pad

maybe kregans gave me the wrong size pad? what else is new??

Ill check them out.  I dont know why I would have put it back together wrong.  I think my rotors are shot because they get realllllllllllly hot when Im on trails and riding the brakes down long hills.  Even with engine braking I still have to ride the brakes and they get so hot they dont even work.  Im sure it has warped the rotors.  Brake pads are probably old now 9 months later and after plenty of excess heat.  TIME FOR VENTED ROTORS.


Correct me if Im wrong....V6 calipers and rotors and rear drums are larger than 4cyl....right? I thought I read that somewhere before.  I have no experience with the V6 models

thanks dudes

[blyota91]

If your brakes are getting that hot then you could have boiled the fluid which creates air in the system, brake fade.  Try bleeding them if you haven't already.

[Tallchevy]

Flush the old fluid out. Another thing that could happen is a bulging brakeline. Check your lines for blistering   

[fordh8r]

when they are that hot, are they real smelly also? if they aren't smelly they're probably at a normal temp. Remember, you're converting the energy of motion to heat and if you ride the brakes for a good while they will get very hot. even normal braking will cause the brakes to get hot enough that you might not be able to touch them comfortably. Someone mentioned brake fade. Brake fade occurs when the gases (that's the smell of burning brakes)from the brake pads gassing out is so much that it causes the pads to sorta 'hydroplane' on the rotor and thus lose brake effectiveness. If the brakes have overheated at some point they may be badly glazed and causing the braking issues you mentioned which can also cause heavy squeeking. Hope you find the problem.

[fordh8r]

I reread your original post and you mentioned having to pump the pedal twice and you hear a clicking. Are you sure the clicking is from the front? Have you checked your rear brake adjustment? If the rears are way out it will cause you to pump the pedal to gain more fluid to the rear wheel cylinders to move the shoes outward until they contact the drum and then they will hold just fine as if no problem at all. The clicking can come from the rears also if the wear pads on the backing plates are grooved from the shoes rubbing on them and they may have a slight lip which the shoe passes over during application with the added travel if they're misadjusted. Check this by applying the brakes (not the parking brake) with the vehicle sitting still and the engine off to closely listen if the noise happens and where it's coming from. Also does the pedal slowly sink while applied for a steady lenght of time (about a minute)? Again, hope this helps.