My thread on NATO got kinda hijacked so I figured I would start one here too. I just picked up an 87 TC with an extremely hard brake pedal. It is nearly impossible to stop.
The first thing I noticed is that there was an unplugged relay under the vacuum tree that goes to the pump motor. I also noticed that the line coming out of the reservoir was clamped off with a pair of vise grips. The fluid was also a little low. I topped off the fluid, plugged the relay in and removed the vise grips from the line. The pump motor now runs when the ignition is turned on but doesn't seem to build any pressure because it runs continually and the pedal never gets softer.
Is this an indication of a ruptured accumulator? Why would the previous owner have clamped the line off? I can find no leaks with the vise grips removed.
I used the article at NATO for troubleshooting. http://www.turbotbird.com/techinfo/TEVES%20II%20ELECTRO-HYDRAULIC%20BRAKING%20SYSTEM%2087-88%20TCs.htm
Here are some pictures of the unplugged relay and the clamped line location.
(http://img.photobucket.com/albums/v648/Loaded87IROC/018-1.jpg)
(http://img.photobucket.com/albums/v648/Loaded87IROC/017-1.jpg)
Well, the pump running continuously and not building pressure,
sure sounds like a bad accumulator to me .
I hjve no idea why the vice grips would have been there
looks like they were there so it would build pressure.
I just read your other post , If you have another accumulator to try, it only takes about a minute to swap one out .
Yeah, I have a whole extra power brake assembly the guy gave me. He hadn't even opened it from whoever he bought it from on ebay.
(http://img.photobucket.com/albums/v648/Loaded87IROC/b1db5bd6.jpg)
I think you got a great score then :D
I agree, a pretty good deal. Do you think I can unscrew this accumulator safely? Like there shouldn't be any pressure in it, correct? In either one for that matter.
There shouldn't be any pressure in either one , you should have no problem .
I had just replaced my accumulator in my Mark VII when I sold it ..
I will try and remember where I got it , and post you a link
I remember reading back when I had my Supercoupe that a place called Prior sold them but its been a few years now.
Thanks for all your help. I will post up results.
I swapped out the accumulator balls but nothing changed. The pump still just runs continually but doesn't seem to build pressure. I let it run for about 45 seconds then pushed the pedal and it felt the same. How long does it take to charge up a fully charge it up? Maybe the pump is weak or another bad accumulator?
Its should only take about 30 seconds to get pressure .
Ok, so my pump is running when the ignition is on but it never stops, so I assume it never reaches the needed pressure because the brake pedal never gets softer. So I guess accumulator #2 is bad also, which sucks.
Now from my research, I can get an accumulator from a TC, Mark 7, or SC and possible some Buicks. Is this correct?
how are you sure its the acc. ball and not something in the pump or something else in the teves unit?
Since you have a whole other unit, why not swap it all out and see what happens?
Some Saabs, Mopar minivans , Cadillacs, Merker Scorpio and others the important thing is that the threaded nipples match up.
I do agree with BogusSVO you should try swapping out the other unit before buying any parts
Hi all.
The accumulator is just a small fluid tank with an air (nitrogen actually) bladder inside to give the system some reserve pressure. When it goes bad you get a very quick cycle pump, and no assist after 1 pedal stroke. You lose capacity since you can't compress a liquid, thus the compressible bladder. The accumulator doesn't do anything else and has no moving or mystical parts in it. (Works just like the water tank on a well system in a house.)
It does hold up to 2000psi when loaded, so just make sure to pump down any pedal assist and leave the key off when removing it and you'll be fine. The factory always said 50 pedal strokes, but experience showed that you just want a rock hard pedal.
I stumbled across this link, check it out
http://www.thelincolnmarkviiclub.org/phpBB3/viewtopic.php?f=12&t=3591
Thanks for the info guys.
I went ahead and swapped out the whole system but 2 of the brake lines stripped, even with me using a flare nut wrench. They were pretty corroded. I am now waiting to see about picking up some used lines and will update this when its all back together. I will say this though, that thing was a real pain to swap out. I ended up taking off the upper intake (I needed to change oil pressure sender anyway,) alternator, and power steering pump and brackets. The stuff inside the car was even worse! I took the seat out to lay down but man those stupid nuts are in a near impossible place to loosen. I hope I never have to do this again!
the inside is not as bad as you think, or should say there is a simpler way...put the seat all the way back,drop the steering colum, then with a long (20-30 inch long) snake thu and remove the nuts
Hmm, maybe Ill do that when I bolt it back in. Thanks.
Ok, so I have a new problem. I replaced the brake lines (Thanks HCOR!) and filled up the reservoir with fresh brake fluid. I took off the back wheels to start the brake bleeding but when I had my assistant hold the pedal down after the accumulator filled up (about 20 seconds) nothing came out when I opened the bleeder screw. I tried several times on both times and not a drop of fluid came out of either side. What am I doing wrong?
Not to add insult to injury, But I have a power booster, master cylinder and prop valve for an 86 Turbo Coupe if you decide to switch over to a simple system. I know it would be ABS but it is tried and true and works.
Thanks for the offer John. I don't think I'm quite ready to give on this system quite yet, but I will keep it in mind.
I think I have a proportioning valve problem. It appears to have locked out the back brakes in a fail safe type mode. I will do some more reading and update when I find something out.
there is nothing to block fluid going to the rear calipers in the prop valve...
fluid will run in and out and the only ele conn is for the light on the dash...
So far all the research I have done has shown me that if if a brake line fails the pressure difference in the prop valve will cause a piston in the valve to shift to one side, blocking off that line and retaining the ability to build pressure in the system. Apparently some vehicles even have a small button to reset this piston. Is this not the type of setup that is on our cars?
Here is one of the threads I have found regarding this.
http://natomessageboard.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=1;t=022545#000000
nope... it is not
when pressure is lost it flips the switch that turns on the red brake light on the dash...
I have a spare 87/88 TC combo valve....
lets see if I can walk you thu this.... you have 3 lines from the Teves unit, one goes to the driver front caliper...
the other 2 go to the combonation valve.
this is what you see when mounted in the car...
with the pressure switch pointing towards the rear of the car.
(http://i261.photobucket.com/albums/ii49/BogusSVO/DSCF4912.jpg)
now when you look at the bottom....
the larger,1/4, fitting goes to the rear of the car (right in the pic) and the smaller,3/16, runs over to the the pass side brake caliper..
if you get a leak it will flip the switch on and turn on the red light on the dash, so you know you have pressure loss.
if this happens you should be alble to slow down/stop on the driver side front brake.
(http://i261.photobucket.com/albums/ii49/BogusSVO/DSCF4913.jpg)
on the front of the combo valve, there is a nut you will see, this is a valve that will move, to allow pressure from the rear brakes to be released, but still hold a slight amount so the calipes do not empty.
(http://i261.photobucket.com/albums/ii49/BogusSVO/DSCF4911.jpg)
the nut removed, the spring and valve removed.. as you can see this one is nasty and the valve was not moving...
(http://i261.photobucket.com/albums/ii49/BogusSVO/DSCF4910.jpg)
if this valve locs up/willl not move, it could be corroded, or have trash in it and fluid will not flow as it should
since you are not getting fluid to the back, unscrew the nut and inspect.
there is a small O ring on the valve
Wow, thanks for those pics! Thanks! I took it apart and everything was nice and clean inside but I had to use a pair of pliers to pull the valve out of the body. I tried getting fluid out of the rear with the valve out and I was able to get some. I did lose that little washer (shot right out of my hand) when I was trying to put it back together though. Is that going to make a difference? I do have another valve coming but I'd like to have a good working spare.
Thanks again!
(http://img.photobucket.com/albums/v648/Loaded87IROC/e83c8281.jpg)
looks like your missing the oring on your green valve...that washer is there so the spr0ng will not eat into the alum nut
if you look midway down the bore, towards the teves unit feed lines you will see a small hole, make sure that is not clogged
I just had a thought... think it maybe in the ABS ECU unit locking up that valve??
Hmm, I guess it could be that too huh? Too much to go wrong with this brake system! I do have an extra ABS computer if it comes down to it though. Thanks for the follow up thought, much appreciated!
make sure the ABS ECU numbers match, I heard once ( and I am not sure) that there is a diffrence between the 87 and the 88 ones and do not swap around
Sorry somehow I missed this thread...
I had the same problem trying to bleed a system with replacement unit, what I did was use a vacuum pump on the rear bleeders till I was sure all the air was out... Unless you figure out how to seal the threads on the bleeders when pumping the fluid, you will always get some bubbles, just have to judge by the amount of fluid pulled from the reservoir...
BTW as already mentioned the accumulator will only cause a short cycle not a continually hard pedal... They have a internal bladder that if ruptured allows it fill with fluid eliminating any reserve...
Thanks for commenting TurboCoupe50. I saw the post you made in the thread I posted a link to earlier where somebody had the same problem. I went out and bought a vacuum pump but still wasn't able to pull any fluid from the rear with it. Unfortunately, the original poster of that link never updated with his solution to the problem.
I was able pull some fluid from the rear bleeders after disassembling the prop valve and putting it back together (temporarily) without the spring. Hopefully my new one will be here today.
whats the update?
Well its fixed but I don't know how or why. New prop valve came in Saturday, I installed it Sunday, but it didn't fix the problem. I put the old valve back in with the insides if the new valve and still nothing. I kept trying to bleed the rear brakes when all of a sudden brake fluid came shooting out. The only thing I can figure is there was a blockage somewhere in the hard line and it worked itself out after my repeated attempts to bleed the brakes. Still have an abs light on but I will worry about that later. Thanks for all the help!
check the rubber flex lines, thet can get an internal rip in them and act as a one one valve....
also is the yellow abs light just on? or is it flashing? if flashing it should flash x amout of times then pause then repeat. if this is the case its a bad ABS sensor, and the flash count will let you know what wheel has the prob.
One of the first things I did was to undo the connection where the metal line meets the rubber line at the rear axle to see if I got fluid there. I didn't, so I eliminated a collapsing rubber line from my line of suspects.
The ABS light is just on solid. I understand there is a connector you can use to pull codes like the EEC connector in the trunk but I haven't looked for it yet.