89 topaz brake problems

[gingerbreadman]

Ok boys and girls, my $500 car has turned out to be worth about 2 zeros less then what I payed for it but heres the most recent issue.

89 topaz

air is getting into the front passenger brake line, I bleed them and its good for a day then my peddle gets all spongy and theres air in the system.

The general condition of the entire brake system is good, I have pulled all the wheels and checked behind the seals of the wheel cyls and no leaks are found, I have jacked up the car and looked all down the brake lines and no leaks noticed, it is not loosing any fluid either, I have checked the rubber brake hoses and no signs of leaking or bulging when brakes are applied or released. I know the condition of the hoses is hard to tell from the outside but is there any test I can do on it? I have the front passenger side off right now.

Does anyone know if this system uses a residual check valve to keep the seals expanded with the brakes realeased? If so im betting the valve is in the little dealies on the bottom of the master cyl connected to the rear brake lines. They don’t get changed with the master cyl, speaking of which I replaced the master cyl 6 months ago so In a parts changing mechanic haist I got a new one on warrenty and put it in but still the same problem.

Im running out of options here and I hate throwing parts at problems but its leaving me no choice.


Anyone?



-gbm-

 

[StangDreamin']

Josh, the check valve is usually in the master cylinder itself - actually, it's in the fitting on the cylinder to the first steel line that goes to the distribution block (the "little dealie" you mentioned). 21 years ago, we bought my wife's (and my) first new car - an '86 Tempo. Ford, Mercury, same little POS bomber car; actually it was kinda fun to drive on twisty roads (with aftermarket struts installed all-the-way-around), but a tremendous PITA to work on. Almost as bad as the '94 Pontiac Gran Prix that replaced it.

I never had the problem you describe (it's sucking air but not blowing fluid anywhere??? ); but I'd bet they might well have changed something with the 2nd gen Tempo/Topaz. If the residual check valve got moved to the distribution block-and it really wouldn't surprise me- then you've probably got a leaker in the short line between the master cylinder and the distribution block. Fluid is going fine from the master cyl through the check valve and the dist block into the front caliper; but the check valve is keeping it from coming back, so it's sucking air through a leakey fitting on the return stroke.
Back then (mid-to-late-80's), Ford kept coming up with all kinds of cutesy-poo little changes to prove their technological prowess; and it kept biting them on the @$$.

Just a WAG that I POOMA.
73 from the Southern part of North America,
KiloCharlieSevenBigDawgPile

 

[80deathtrap]

Looking at my Tempo/Topaz repair manual it says the little "deailies" on the bottom of the master cylinder are pressure control valves for the rear brakes. The front most goes to the right rear brake and the rear most goes to the left rear brake.

Most likely it they are not your problem as they are almost completely isolated from the front brake. The only thing connecting it to the front brakes is the master cylinder as there is no distribution block. You said air is getting into your front brakes is it just one or both of them? They are on seperate circuits and completely isolated from each other so you have two problems if it is both front brakes.

However, I've experienced similar problems on a different car and I would bet that your problem is a worn out o-ring seal in the front caliper(s). The o-rings serve to seal the caliper piston to the caliper bore but just as importantly it serves to pull the piston back when the brake pedal is released. A faulty o-ring seal will give the impression of a spongy pedal no matter how many times the system is bled. The brakes may feel firm initially but it will go soft shortly thereafter. You may not notice any leaking fluid but would likely notice that the brake pad doesn't pull back much if at all when the pedal is released.

 

[StangDreamin']

Hey, yeah. I never thought of that Especially since both you guys live up there where it's very likely that all kinds of cr@p would get into the brake assemblies during winter driving.

I never really gave the brakes a lot of thought on that car. Just kept the pads and shoes replaced; I remember I replaced the drums after Mrs StDr drove it back and forth to work for almost a week with the e-brake handle pulled halfway up, and then told mme it was making "a funny noise in back".
(Hey, cut her some slack, she was very pregnant -like a week overdue- with our second child at the time!)

The front discs never gave me any trouble, in fact the whole braking system was reliable as an anvil and it was our commuter car (not a trailer-hauler or anything); so......