Author Topic: Brake problem, 78 Pinto (Read 1651 times)

74WagonMeadowGreen · « **on:** January 15, 2012, 08:53:00 PM »

I have gotten my 78 Pinto past emissions, and have plates. Finally. Much has been sorted out and it is running well, but one nagging problem remains. When the car is cold, and first fires up, if you pull out and hit the brakes (power), it is very hard to get the car to stop... it acts like the booster is trying but not succeeding. Backing my story up a few months, when I overhauled the rear wheel cylinders I fully bled the system, and everything seemed to work fine, but then I read about having to "set" the diverter valve. According to the book, you turn on ignition (not running the car, just idiot lights on) and press down on the brakes until the brake light on the dash goes off. Uh oh, my brake light does not come on! Is it the bulb, or is the diverter shot? Could that be the problem? I fully intend to follow the book procedures to test the booster, as I have no evidence of a problem with the master cylinder. When the car warms up, magically, the brakes work great, and will stop on a proverbial dime with no effort.
I DID replace the original 1978 hose to the intake manifold, and discovered the booster was still holding pressure after days of sitting. I could be wrong, but the booster seems to be trying very hard (when you push hard on the brakes you can nearly kill the motor, partly because I need to adjust my choke idle setting up) then after a few minutes running it all straightens out. Right now, my gut is pointing to the diverter valve being a problem, but until I check and verify the booster, I cannot be sure, and I really don't want to pull the dash to check the bulb (I have done it before... not as bad as other cars, but not fun, especially undoing the brittle speedo cable connector)... any ideas?

RSM · « **Reply #1 on:** January 16, 2012, 12:18:38 AM »

When you say the brakes don't work when it's cold, is the pedal hard to push or does it feel like a normal pedal and the car just won't stop? Does the pedal go to the floor? Once it warms up how does the pedal feel? Something you might want to test is the check valve on the booster. Sounds maybe like it's not working quite right. Have you checked the vacuum to the booster to make sure you have full vacuum? This is something that comes to mind as a starting point when diagnosing this.

tonij1960 · « **Reply #2 on:** January 16, 2012, 04:02:32 PM »

Youre right theres a lot of questions in this question.

I would ask if the back brakes were adjusted out good, I know they self adjust ( I was told when you back up and put the brakes on, and to do this over and over to get them adjusted). But I think using a brake spon is the best way get them tight then adjust them out until they just barely quit dragging. I was told by a guy at Midas once,with rwd 80% of the stopping comes from the back brakes and with fwd 80% from the front brakes. If its true, maybe youre front brakes are coming on before the back ones?
The h valve Im pretty sure is a pressure differential valve. So if the pressure on one side (front) is different than the pressure on the other side (rear) theres a little metal ball that gets pushed over and closes a contact to light the brake light. So if your brake light bulb is bad its probably a good idea to replace it,and see if its coming on when this problem occurs. You can check that brake light pretty easy without removing the cluster.

I remember having this problem with y first Pinto wagon I owned back in 1981 but I seriously cant remember what was done to correct it. I know I had to replace the wheel cylinders for some reason at some time and the rear brake hose. I wouldnt rule them out or the master cylinder.

RSM · « **Reply #3 on:** January 16, 2012, 05:24:54 PM »

Wouldn't it be nice if diagnosing a brake problem was easy?...lol I've ran into so many different brake issues over the years I could almost write a book. Hopefully we hear back from 74WMG soon and see if he has come up with anything.

tonij1960 · « **Reply #4 on:** January 16, 2012, 07:33:15 PM »

I hope hes changing that light bulb

74WagonMeadowGreen · « **Reply #5 on:** January 16, 2012, 10:31:48 PM »

I did change the bulb today, and it was not only inaccessible but required disconnecting the speedo cable (a royal pain), and pulling the cluster out far enough to access the bulb holders. This job is MUCH easier on a 74. I am surprised that as identical as the dash looks, just how much changed behind. Regardless, I managed to get the bulb working fine. The brake bulb now comes on with all the dash lights, and goes off unless the emergency is pulled. It has NOT come on under any other circumstances. I will try to outline my problem a little more clearly. All the brake fluid was replaced with fresh after I rebuilt both rear wheel cylinders. I also adjusted them to the correct position when all was back together, so adjustment is not an issue. When the car is started (and with the winter lately, in very cold weather) and one backs out and you push on the brake pedal, it is as if the booster is not assisting, the pedal is rock-hard, and will slow the car, but it takes much effort. Add to that if you continue pushing, it could stall the motor. As the car warms up, and this is not a gradual transition, the brakes suddenly require virtually no effort and seem to work absolutely perfectly, and for the duration of the drive. I did discover a small amount of fluid seepage on the bottom of the master cylinder, but after driving today discovered my cap gasket leaks miserably, so a new one is forthcoming. So... the brake warning light appears to be operating correctly, and is NOT indicating any malfunction with the proportioning valve, not that it would necessarily, but thus far, only the warning light is corrected. I will next do all the book tests on the booster, to determine its viability.

RSM · « **Reply #6 on:** January 17, 2012, 12:07:03 AM »

Sounds like you have a booster issue. What you described points right to it. I would take a look at the check valve and check and see how much vacuum you have. Sounds to me that vacuum is more the issue. Usually if a booster is bad it's bad all the time....usuall y. To me it sounds like you have no vacuum to the booster after start up then over time it becomes enough to operate the brakes correctly. Let us know what you find.

74WagonMeadowGreen · « **Reply #7 on:** January 17, 2012, 04:10:59 PM »

Thank you, that sounds like an excellent direction. It is supposed to warm up from single digits this morning to the 50s over the next several days, so I will borrow my Dad's vacuum gauge and take a reading. I will also perform the other indicated booster tests according to the manual and see how it all plays out. I will keep you posted. Again, the suggestions are all welcome!

D.R.Ball · « **Reply #8 on:** January 17, 2012, 05:19:52 PM »

Sounds like the brake booster. You can find them online or in store. If you buy a new one save your money and buy the booster and the master cylinder. When you change the booster and master cylinder be very careful about the break lines or you will have to replace those as well. Also you have to separate the M/C from the booster because it will not fit as a unit.And one final note when you remove the brake light switch do not lose the pedal bushing they are hard to find separately online.You can buy a new brake light switch with the bushing though.

74WagonMeadowGreen · « **Reply #9 on:** January 17, 2012, 10:06:18 PM »

Sound advice, again, thank you for the input. Funny you mention about the M/C, as I was just pondering the booster's removal, and I have a rebuild kit for the master cylinder anyway, and if I have to remove it, thus rebleed it all regardless, that is a great excuse for an overhaul or replacement. The booster is unfortunately the more expensive item... and no way around that! I will make all the tests first, as time and weather permit. Thank you!

74WagonMeadowGreen · « **Reply #10 on:** January 18, 2012, 12:35:03 PM »

I found this on another "help" site... it sounds possible:

"Issue is moisture getting into the check valve in the line between the brake booster and the manifold. Unfortunately, in really cold weather you have condensation when the car cools down, and if the condensation happens in the line/valve and freezes, the valve can't move.

My solution was to remove the line, and run WD-40 thru it to remove the water. Blow the excess out, and re-install the line. Make sure you get the line back in the right orientation, or you really won't have any brake boost.

A new line/valve likely won't fix the issue, unless the orientation of the valve is different and no longer subject to water pooling at the valve and freezing.

Also, under conditions that will likely show the condition (really cold times after the vehicle has been sitting outside for a number of hours), I make sure that before I start rolling down the street, I've tried the brakes a couple times. If it is frozen, you can usually get it moving again by multiple hard applications of the brake pedal. Once it's free, I haven't had it stick again for that trip. I make sure they work before I drive off.

Its frightening the first time it happens, but once you realize what it is, you can deal with it. You don't loose braking capabilty. Only power brake boost."

74WagonMeadowGreen · « **Reply #11 on:** January 19, 2012, 11:38:49 AM »

UPDATE: I checked, tested and flushed my check valve, and find no problems with it at all. It functions perfectly, does not stick or leak.
I tried the several tests for the booster, and so far have found no apparent faults. It passed every test so far. I borrowed a vacuum gauge and will test my manifold vacuum as soon as our 100mph+ winds settle down!

tonij1960 · « **Reply #12 on:** January 20, 2012, 04:24:52 PM »

Try to get readings during and after the time its giving trouble

74WagonMeadowGreen · « **Reply #13 on:** January 25, 2012, 09:23:16 AM »

A combination of circumstances has urged me to order a rather nice package at a fair price I would like to pass on to Pinto drivers:
http://www.oreillyauto.com/site/c/detail/A1C0/503205.oap?ck=Search_50-3205_-1_-1&keyword=50-3205

It is a master cylinder AND power booster package for approx. $101. At this price, I would be foolish not to just replace mine as a unit, turn my old ones in as cores to rebuild, and likely solve my brake problem. Since my booster is original from 1978, it is likely that problems with the internal diaphragms may be causing my problems.

BTW- I have been driving my Pinto more, and even when warmed up, although it doesn't kill the motor, if you hold the brake pedal at a light it makes an audible vacuum sound and labors the motor. It seems evident that SOMETHING is assuredly wrong with the booster, and I think this should solve it. I will report back when all is done to describe whether I am right or wrong. Before I call things good, I WILL test vacuum, and make certain there are no leaks or obstructions.

RSM · « **Reply #14 on:** January 25, 2012, 08:47:31 PM »

At that price it would be a very good idea to change it out. Like I said early on...sounds like a booster issue. It's entirely possible it's leaking with the brake pedal applied.

D.R.Ball · « **Reply #15 on:** January 26, 2012, 07:21:34 PM »

Is the car making any noise when you apply the brakes ( whoose sound) ? For $101 plus shipping I'd change both out and be done with it. BTW according to the Ford Manual the check valve is not serviceable IE replacement of the valve will not fix the booster.

flash041 · « **Reply #16 on:** January 26, 2012, 10:16:06 PM »

I just put in the booster/master from Oreilly yesterday.My brakes worked fine , but had a vac leak causing rough idle.

D.R.Ball · « **Reply #17 on:** January 28, 2012, 01:13:41 PM »

You might have disconnected a vac line...There is not alot of room to work with back there.

tonij1960 · « **Reply #18 on:** January 31, 2012, 12:48:09 AM »

Any news from 78wagon?

74WagonMeadowGreen · « **Reply #19 on:** February 08, 2012, 02:28:32 PM »

We had our news-making, record-breaking 24-36 inches of snow two days ago, followed by a second snowstorm and temps down to single digits this morning. My poor 78 is somewhat buried (but covered!!) and that nice, new booster/Mastercyl package waiting inside for transplant as soon as all melts and gets warm enough to tackle it. I will attempt to "bench bleed" it and then install the package and rebleed it. I am fairly confident it will solve my brake issues. I will give an update when the weather permits!!

74WagonMeadowGreen · « **Reply #20 on:** February 21, 2012, 03:24:52 PM »

I installed the new master cylinder/booster setup, and bench bled the master cylinder first. Except for Ford locating the booster nuts in the least accesible places for any tool to reach, all was straightforwar d, and I (hopefully) completed the bleeding. BUT... I pulled the rear wheel to find a load of oil sprayed on the wheel insides on both rear wheels... my new seals are both pouring oil out after only a couple months...

I started a new posting now called REAR SEAL DILEMMA, 1978

74WagonMeadowGreen · « **Reply #21 on:** February 28, 2012, 08:50:00 AM »

Finally, new booster and master cylinder installed, and the brakes are fantastic, and no motor stalling when cold! The new booster is excellent, as is the new master cylinder. Thanks to all for comments and suggestions!

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Author Topic: Brake problem, 78 Pinto (Read 1651 times)