brake pedal went to floor suddenly

[RDetty]

I have a 1989 tc, bought new and the only problem I've had in 21 yrs is with the A/C until now. I stopped to get gas the engine was still running and I had my foot on the brake pedal when the pedal sudenly went to the floor. I turned off th engine got the gas and when I restarted the engine everything seemed OK, for a while. Then I had to turn on the head lights and the gages went crazy and the needles on the tach and speedo started bouncing. I still had brakes but I never knew when the pedal would fade, it wasn't consistant. I parked the car for almost 1 yr and decided it was time to fix it. I contacted Invasion Auto Products in No Hollywood and he said he could repair the Teves ABS system so I took him the Mastercylinder and the abs pump&motor still attached. After bench testing it he said it was not the hydraulic system it was the ABS motor and pump and he repaired it. I installed everything and the original proble was still present. Next Invasion told me to send him just the ABS motor and pump and I did. I got it back in a few days and installed it. The problem was still present. Next Invasion had me drive the car to their shop and they would checked the accumalator. They removed it but they did not check it with a pressure gage and they said it was OK that the problem was a relay and told me to go home buy a relay and install it. I couldn't find a relay anywhere. I took the car to the former chrysler dealer and had their brake specialist check everything. he said there were no error codes and the problem was likely in the hydraulic system of the mastercylinder. I sent the mastercylinder to Invasion after talking to them and they said they rebuilt it and a "O" ring was missing and they replaced it. I installed the mastercylinder again and I still had the same original problem. I asked the chrysler brake specialist about a missing "O" ring and he said it was possible the "O" ring disentagrated with age. Next I took 2 or the 3 relays and had them checked out, they were OK. THe reason I didn't take the one that operated the ABS motor was because I could hear it click when the motor would stop running after it had run for 45 to 60 second when ever I had pumped down the pressure in the accumalator and then turn on the ignition. So I was pretty sure that relay works. The only thing that was unexplainable is once after reinstalling the ABS motor and pump then bleeding the mastercylinder and all 4 wheel cylinders I drove the car in heavy city traffic for about 25 miles and not once did the brakes fade. But then all of a sudden the fade returned. The pedal does not feel like a slow leak inside the mastercylinder like the old vaccum boost type MC use to do when they failed, this fade is sudden and fast almost like a valve was opened.

does anyone have a suggestion what the problem is or how to fix it?

Rich D

dettyr@verizon.net

[Guest My TC Toy]

R, welcome to the thread. Hope that after a little discussion you get the problem fixed. It is certainly an interesting problem.

In reading your problem I interpret that you sent the master cylinder (operated directly by the brake pedal) to the depot for repair twice, and alco the ABS motor and pump twice. My question is are you calling the ABS motor and pump the pump that pressurizes the brake system, that is part of the master cylinder, or the totally separate unit that that sits on the chassis. These systems are different that other cars and frequently the parts names get confusing.

Please advise.

Bob

[Bill Reichert]

Rebuilt master cylinders are not to be trusted.

[RDetty]

Bob I mean the pump and motor that are attached to the mastercylinder and provide the pressure to the mastercylinder and to the rear brakes. I did not mention before the brake light and the ABS light work as it is described in the owners manual. They come on for a few seconds when the engine is first started and then go off. If I pump the pedal rapidly 4 or 5 times while the veh is running the ABS light will come on but go off a second or two after I stop pumping the pedal. I think it is a intermitant electrical problem or air in the main valve. I have tried to bleed the mastercylinder but I don't think I am doing it right. The Teves II on the 1989 does not have a bleed screw on the master cylinder I was told to pump down the system with the ignition off then losen one of the bolt on the high pressure hose from the pump to the mastercylinder and turn on the ignition and let it purge the air and when it stopped sputtering tighten the bolt and it was bled. All I seem to do is blow out the "O" ring. Does anyone have another way of bleeding the mastercylinder. It may be a mute point and this is not connected to my problem.

[Guest My TC Toy]

R, the problem I am having is the fact that the brake pedal "went to the floor", the 'master cylinder', has three independant braking chambers - front left, front right and rear. Even if the rubbers failed in one of the chambers the other two would still function, allbeit a little less efficiently. The fourth chamber in the 'master' is the pressure pump that brings the system pressure up to 2700 PSI, then the accumulator stores the pressure for multiple uses before the pump cuts in and brings the pressure back up. It is basically the same as a normal vacuum braking system but controlled electronically and with greater pressures.

Even if you loose all pressure the pedal will not go to the floor but will be hard.

The only thing that would cause a total failure, and the brake pedal going to the floor, is a total fliud loss. But where is the fluid going?

Do you have any fluid stains in the driveway?

Is your brake fluid level going down?

If yes, you have a leak. If no the fluid must be bypassing internally. If you had the 'master' rebuilt the problem is probably not there, then the only other culprit is the actual ABS assembly, located on the chassis. The ABS controller is the unit that actually frees the brake rapidly to control a skid. This is done electronically through the manipulation of hydraulic valves in the controller. I honestly do not know if this controller can have a total failure

but there are lots of rubber seals in there that can potentially fail.

Hopefully someone else will make a comment before you continue on, and get a better feel for the solution.

Good luck.

Bob

[RDetty]

Bob, I said the pedal went to the floor, that probably was an overstatement. The pedal went down as far as it will go and I still had my front brakes and everytime the pedal fades and goes down rapidly I have front brakes. The other day I drove the car and I had to apply the brakes hard when a another car pulled out infront of me, it happened so fast I don't know if I lost the rear brakes but my car pulled hard to the right. It felt like the righ front wheel had locked up. I think I said before I had the brake specialist at the former Chrysler dealer do a diagnostic check on my car and he couldn't find anything and there were no error codes displayed. After Invasion rebuilt the mastercylindr and it still did not solve my problem I talked to the chrysler brake mechanic he's the one that thought my problem was in the hydraulic part of the mastercylinder. He then said it could be an intermitant electrical problem and I should check all the wire and there connections at the relays. I have not done that yet.

FYI I found a company called ABS MASTERCYLNDERS and they said by email they could rebuild the MC for $650. They also said they are a manufactuer of custom mastercylinders and they can make any part that is not available anymore.

Rich

[TwinCamFan]

Early in my TC ownership after I did a 'brake job' I did not properly bleed the rear brakes and the symptoms were very similar as you described. I coud use the brakes, even use them fairly hard but if I applied them QUICKLY, like a stab, the pedal would be soft and only one rear (and maybe one front) brake would work and that upsets the braking balance of the car something fierce:eek:

The whole fix was to simply *correctly* bleed the rear barkes. Did you do the rear bleeds, key in the on position thus letting the ABS pump completly rid the system of air? Fronts are done as a normal brake bleed with a friend depressing and holding the pedal as you opening and closing the bleed screws.

I respect how much work you have put into the brakes already, I think I would have given up by now:o

Alan

[Guest My TC Toy]

All of us here are more than willing to help a fellow TC owner, but we cannot check the car itself. Consequently we must rely on accurate information the person gives us. Your description of the problem now is entirely different than originally given.

Like Alan said, did you properly and thoroughly bleed the rear brakes using the quick procedure Alan gave you?

[RDetty]

I bleed the brakes as Alan instructed at least 6 times. RR wheel first LR wheel next RF third and last the LF wheel. Thats how the Chrysler repair manual described. Ignition ON when doing the rear brakes. It also said it was not necessary to pump the pedal when bleeding the rear brakes it was only necessary to partially depress the brake pedal. I've run 6 qts of new brake fluid thru the system, should be really clean now. My problem hasn't changed, the brakes pedal fades but it is not consistant in the way it fades. Sometimes it is fast and goes down as far as possible, kind of scary when that happens, then other times its slower and seems to hold part way down and the pedal is firm and the car stops. Nothing is consistant about my problem that may be why it sounds like I am describing a different problem. I have never lost the front brakes but the front brakes alone do not provide good braking. As I said earlier, the other day I had to hit the brakes hard and fast and my car pulled hard to one side. I was only going 10 to 20 mph when I hit the brakes.

Friday I ran accross a old thread (i think thats what you called them) and someone described a way to test the accumulator with out a pressure gage by turnng on the ignition and waiting until the ABS motor stopped running and the yellow ABS light went off, then apply the pressure to the pedal and count how many times it could be pumped before the yellow light came back on. I tried that and only got 3 pumps on the pedal before the yellow light came back on. According to the thread 4 or less pumps on the pedal means bad accumulator. I am going to purchase a new accumulator and see if that works. My accumulator is the original 22 year old one so it probably needs replaced anyway. I read somewhere in the threads the accumulator should be replaced every 5 yrs. Now does anyone have any additional ideas?

Rich

[Guest BarelyFit]

Until you get the accumulator swapped out; no.

When the pedal goes to the floor does the RED Brake light come on?

Be wary of NOS Accumulators. There are 20+ year old accumulators being sold (Amazon). Try to find a newly manufactured one. (TC Parts). His name is scattered through out this forum.

[RDetty]

1989 TC Royal,

No, the red brake light does not come on when the pedal goes to the floor. The brake light and the ABS light both work as the repair manual describe they should when I first statt the vehicle and they go off in a few seconds.

When the pedal goes to the floor and if I immediately let up on the pedal and reapply pressure to it I have what feels like a normal brake pedal again but that will only last monentarily before the pedal starts going down again. Sometimes the brake pedal goes down as far as it will go and sometimes it will only go down a little ways and hold. It is not consistant.

I called TC Parts and spoke to Andy and I explained everything. He said it didn't sound like a bad accumulator but since its the original 22 yr old accumulator it should be replaced. He told me Larry is who I need to talk with and suggested I email him with all the details about my brake problem and I did. I am waiting for a reply.

Rich

[TwinCamFan]

Detty, I reread your first post but not sure if it covers if the front calipers were replaced OR taken off the car? On another FWD Chrysler a few years back (not a TC Masi) I did the 'whole 9 yards' Brake job, rebuilt calipers etc. Soft pedal after the job (yet not intermittantly so) bled and bled and bled... Still soft. I had put the left capliper on the right and right on the left. They bolted up just fine but the bleeder screw is not at the top that way and a big pocket of air will be trapped even with endless bleeding. Just a thought...

Alan

[RDetty]

Thank you Alan for the info, I will remember that if I ever R&R the front calipers. I have not removed anything except the Master cylinder assembly.

I got a email from Larry at TC parts and he said it sounds like a bad accumulator and it could have over-heated the relay and melted the wire under it. Regardless of what the solution is I think I should replace the accumulator and relay next. Anyone know how I can check the wire under the relay? Wires to relay box are to short to turn it around to take a good look and I can not tell if its melted.

Rich