1996 mazda familia pick-up brake problems
 

The rear brake drum is binding and getting very hot. I have replaced both side with new slaves and replaced the servo together with a new master cylinder. The brake pedel will start off in the normal place but after a short time using the brakes the pedel become higher and goes heard. Then the rear brakes start to over heat. Why is this I just don't know what to do next.
I have also replaced the front near side slaves as well as one was leaking. The master cylinder was leaking into the servo so I changed both of them. Now I back to the beginning again.
Can anyone help me with this dam car's brakes.

Thanks:confused:

2 things I can think of:

The bracket that actuates the handbrake inside the drum may not move freely. In my '98 Protege I had to put it into a vice and use a hammer to get it unstuck.

The brake hoses may have deteriorated internally. Basically it creates a blockage. Your push on the pedal is strong enough to make the fluid pass, but the return springs are to weak to do the same. Therefore the brakes bind.

Re 1996 mazda familiy pick-up brake problems
 

Hi there.
Manythanks for your help. I have done some more work in these dam brakes but the problem is till their. I have changed all the flexible pipes and three copper pipes as I could not get the slaves off without the locking nut rounding off. I have been looking at the rear off side as this seems to be the one that is getting hot. I have looked at the hand brake system and it seems to be free with no sticking at all but I had to releace some fulid from the system to push the slaves back in. Then I can get the drum back on. These atr new slaves and are not sticking at all but they wont go back correctly. This is the same where I started from. Just 3k Baht latter and no improvment.
I just do not know where to go now or what to do. I have almost replace the hole system now.
Swifty

I was reading through your original post again and yes, you almost replaced everything but the servo. I assume servo is the same as 'brake booster", a can with a membrane that hooks up to the vacuum at the intake.
You said that brake fluid leaked into the booster. Maybe the booster got damaged so now it is unable to return after applying the brakes? I am setting this into a question, because I don't know. But I would try to check this out.
Do you have strong legs? If so you could disconnect the vacuum hose and drive slowly on a empty road (slightly uphill if possible). See if the symptoms persist. You need strong legs because you would drive with out brake assist.

I also think it is possible that a new part may be faulty. Maybe the wheel cylinder on the brake that get s hot. Did you use new springs inside the drums?

Re Re 1996 mazda familia pick-up brake problems
 

Hi again. Yes the servo unit is the same as a brake booster. I have replaced this as the old obe had lots and lots of fluid from the faulty master unit in it. I have now replaced the rear shoes and the return springs. I will let you know if the problem is getting on or have I fixed it??? lol:rolleyes:.
If this does not work I will peplace the remaining front parts and that will then be a complete new system apart from one pipe from the back to the master unit. I have change the others as the locking nut could not be removed without it rounding off. Or it may find it's way to the edge of a cliff.:eek:

On another forum I learned something about changing out a master cylinder. In that case the master cylinder was mounted to the firewall so it was pointing up, not level. In that case it was necessary to bleed the master cylinder on the bench before mounting it in order to get all the air out.
For that person it was too late so he had to jack up the rear of the truck until the master cylinder was level and bleed the system again.
....just something to check.

Also it wont hurt to try and cycle the ABS system (if installed), best is on a dirt road so the wheels will really lock up and cycle the ABS module, could be something stuck in there holding the rears on.

Many thanks for that but that is not a problem on my pick-up. I have now changed all the parts at the rear end and still the problem with binding rear brakes. Just waht do I have to do get this dam car working without heating the brakes. The pedel will become harder and harder and will travel less. After they have cooled down again all is well again. WHY????????? I just don't know what to do next. But the cliff edge is getting very close now.

AHHHHHHHH, I misread then sorry. Does this still happen if you unhook the vacuum line for the booster? Did you clean out or replace the proportioning valve(s)?

Swifty: I once had that problem in a VW beetle. The mechanic had the brakes adjusted to tight and the slight friction caused enough heat to expand the fluid. Then the brakes were binding really bad. You had to adjust these brakes by hand. your brakes have automatic adjusters.
Then I had a similar problem when I first did the brakes on my '98 Protege. There is a lever sticking out of the backing plate and the handbrake cable sits in there. Inside the drum this lever is attached to a bracket that spreads the brake shoes when you apply the parking brake. This bracket also has a small ratcheting cam on it. This ratcheting cam is the automatic adjuster. The key is that all these parts have to move freely. The brake dust and the heat can make these parts stick. My problem was that the lever that goes through the backing plate was not rotating freely on the bracket. I had it loosened once but after a short time it was binding again. So I took it apart again and loosened it once more. I used penetrating oil and brake cleaner liberally. I moved it around until it had some play. Then I applied some anti-seize compound. (very little and none on the braking surfaces). Only then did my brakes return properly. I am referring to the shiny part above the blue mark. http://img.happywrenching.com/mazda/...ading-shoe.jpg

Hi there. Many thanks for your message. Yes I have been slowly adjusting the rear brake adjusters as they are manual and not self adjusting type. They have seemed too improved a bit. I will do more this weekend. But very interesting your comments on the overheating brake fluid. That may just be the problem.
I will kept you know how I get on.

Hi all. Well I have done all I can now to this dam Mazda. I have replace nearly the whole system now and it still looks up. Now the front is doing it. So what I have done is back off all the adjusters so that the bakes will only work when the pedal is almost on the floor. I drove to work (2.5Km) and back again. and yes you guessed it by the time I got back the brake pedal was all the way to the top with very little movement will operate the brakes and then they get hot. very hot.
The car is now standing on the edge of the cliff but as the brakes have jammed on I can't move it. I have changed the no return valve between the engine and the servo.
I just do not what to do now. I will have to try and take it into a garage but trying to get them to understand what I have done will not be easy as my Thai is far from good.
I will let you all know what happens!!!!!!!!!!!!!!!!!!!

Maybe the problem starts at the front. They are disk brakes, right? The calipers must be able to move sideways. So take the wheels off and grab the calipers and push/pull on them. They must move with ease. If they don't move the sliders are likely all caked up with rust and corrosion. Sandpaper and light cover with high temp grease should make them go again.
I had to use sandpaper wrapped around a wooden dowel to open up the holes for the sliders inside the caliper.
There are rubber pieces that supposed to keep dirt and water out of the sliders. They can jam the sliders if there is rust behind them.

Of course you could also use another vehicle and push that thing forward by 5 feet or so!

Hi there. Yes the problem is still there with or without the servo/boster unit connected

Hello to you. I have replaced all but two front slave cylinders and most of the brake lines now. The two front slaves seem to be working fine so I have left them.
My observations are that as the brakes are used all the slave cylinders move out them return under spring pressure. But after a very short time the all stop doing that and will not return at all so the brake pedal gets higher and higher until there is no more movement to be had then all the brakes start to bind up and get very hot.
One thing I have noted is the gas regulator has been mounted just in front of the master unit and get hot as a result. Maybe this is what the problem is over heating the master unit and the fluid and expanding it making the brake come on and not letting the fluid return??????

Slave cylinder in the front? That means you have drum brakes in the front. They are usually called "wheel cylinders".

Gas regulator? Are you referring to a fuel pressure regulator? Nothing related to the fuel delivery system should get hot anywhere.
Or are you referring to a catalytic converter? These suckers get very hot and they normally have heat shields around them.

Whatever it is you could put a heat reflector between the parts in question to see if it makes a difference.

Could you take a picture of the area and post it here?

Yes the car has drum brakes all round. I have put some heat reflecting material between the Gas regulator and the master cylinder. This has made a difference but to problem is still going on.
One thing I have noted. Is that yesterday we had a big rain storm and lots of water all over the road. The engine cooled down and so did the wheels. The brakes where hard but when I got to where I was going only some 8 km the brakes came back to normal and stayed there. Then all the way home again. This problem is therefore defiantly heat related and not something jamming in one of the drums.

Now we are getting somewhere.
Please, clear up for me what a "gas regulator" is. I believe you mean " catalytic converter". Do an image search for the two terms then you will be able to tell.

It is likely that your truck has lost the original heat shield. Try to find an original one or at least some pictures of an original one so you can fabricate a replacement.

Keep in mind that gases expand more than liquids under heat. Either the liquid starts to boil or there is still air in the area that gets heated while operating the vehicle. I would flush the fluid. It is not that expensive.

Hi Again. Yes I’m beginning to think that there may still be some air in the system and that's what is getting hot making the fluid push the wheel cylinders out.
The gas regulator is directly in front of the master cylinder. The car is only running on gas at the moment as I have not got a working petrol pump. I will be looking into that this week as I need to sort it out. It has been this way since I got it. Running on gas that is. the brake problems have only started since I had new rubber pipes fitted as they what a bit on the bad side. Like splitting. It has gone downhill since then.

Swifty: you really could have helped us by telling us how the truck is set up. I had no idea that it is capable of running on 2 fuels.
Explain to me why should the gas regulator should get hot? Which kind of gas it using?
I really have no idea about gas as fuel.

Either its running on LPG/LNG/CNG or wood gas as the secondary fuel, either way I think it would be difficult to run that old of a vehicle on both. Like Tanprotege said it would help us all out alot if we knew your vehicles setup, we know it has 4 wheel drums which means its pretty old for one (or a model not sold in the US anymore) but knowing how the rest of the engine is setup would help us out tremendously.

1996 mazda familia pick-up brake problems
 

Hi there. I'm sorry if I have missed led you. But yes the car can run on two fuel systems but the petrol side is not working. Yet.
The gas regulator is heated by the car cooling system as gas works better when hot as the gas heats up it will change from a liquid to a gas vapour and then into the engine via the cab. No petrol will flow just gas vapour.
The car was like this when I got it some 5 months ago now. The brakes worked just but on close inspection revealed the flexible pipe to be in a very poor condition so I had them replaced by a garage close by.
Then all the problems started. And so it goes on.
The gas regulator is less than one inch from the master cylinder and get hot to as is so close. I have no idea how long this problem has been going on as the old owner only used it to transport tree and flower from his shop.
I hope this will give a better insight to the cars history and hope you will have some more ideas on what to do with it. I think some air trapped in the master cylinder and when it gets hot the air will expand and forcing the brake fluid along the pipe making them start binding. This make them get very hot and more heat more binding until there is no more movement in the master cylinder and they all jam up.
Well that’s my theory.
Any other seductions are welcome
:mad::):confused:

Ok put some aluminum foil around your master cylinder as a TEMPORARY heat shield till you can make one out of steel, do not make it tight leave it loose so air can flow around the master cylinder, this should block most of the heat from radiating from the regulator to the master cylinder.

Thanks, Swifty.

I would place a shield around the gas regulator. Leave some space for air. I would use aluminum, maybe from an aluminum can (or steal a sauce pan from the kitchen ;-)). Direct the shiniest side to the heat source. And I would put a heat shield around the master cylinder, again shiniest side to the heat source. I am thinking that 2 walls and 3 air spaces should be enough to keep the fluid from boiling. See if you can get a little more space between the regulator and the master cylinder.
Change the fluid with fresh one.

If you still have problems you could switch to Silicone based fluid. It is more expensive but it has a very high boiling point and you don't need to change it that often. If you go this route you must completely clean out the fluid you have in it now.

He has front drums as well so there is no bias valve in the system, IIRC bias valves are only installed on a vehicle when it has discs in front and drums in rear to lower brake pressure to the rears since drums are self energizing BUT there might be a residual pressure valve somewhere to maintain a minimum pressure in the lines so the springs dont force the wheel cylinders all the way in and this could also be sticking.