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Rick_Leuce
06-05-2015, 01:26 AM
Hi,

I recently acquired a 1990 Thunderbird SC that, according to the previous owner, the only issue was that the "Anti-Lock" brake light is on and that he didn't know what caused it. A couple days after I bought it and I needed to stop quickly at an intersection, the brakes got hard and it didn't come to a stop as quickly as my 1991 (almost didn't stop in time). The next day, I realized that the ABS system is always trying to charge the accumulator ball, but never seems to get fully charged and won't shut off. When I turn the key in my 1991, it takes less than a minute for the accumulator ball to fully charge and I can hear the pump shut off. After about 2 minutes, the pump for the Accumulator ball in the 1990 sounds like it gets close to fully charged, but the pump still won't turn off. Even after swapping the accumulator ball with another used one, the pump never seems to shut off. Somewhere I researched said that it is bad for the pump to be running constantly without ever shutting off.

I'm not sure whether or not the problem lies with the accumulator ball itself, but I have a feeling that something else in the ABS system has gone out. I was interested in trying to replace the whole ABS Hydraulic Unit with a rebuilt, but cant seem to find any in stock.

Any ideas or suggestions on how to test to find the true problem or where to get replacement parts. Do I need any special tools to bleed the replacement system (bench bleed, etc...)? Is it possible to test an accumulator ball?

Thanks :)
-Rick_Leuce

sam jones
06-05-2015, 04:28 AM
Good morning

You might have a bad ABS pressure switch. There is symptoms/troubleshooting information in search. Good luck.

SuperChicken89
06-05-2015, 09:44 AM
Hi,

Even after swapping the accumulator ball with another used one, the pump never seems to shut off. Somewhere I researched said that it is bad for the pump to be running constantly without ever shutting off.

-Rick_Leuce

Was this a known good accumulator? If the accumulator can't build enough pressure to reach the propper pressure to turn off the pump, it will run constantly until the key is in the off position. A bad pressure switch would cause the same issue. I would start with a known good accumulator before changing the pressure switch. You can't trouble shoot a system without known good parts.

The pressure switch activates the pump motor relay. The pressure switch is activated by the accumulator pressure. The pressure switch is in the closed position until the pressure built up in the accumulator which then opens the contacts in the switch.

Bryan

Rick_Leuce
06-05-2015, 01:22 PM
I'm not sure whether or not the Accumulator Ball is bad, I don't know how to test it, and I can not order a new one (Spinning Wheels SC is out of stock) I was hoping there is some testing process that could help me determine if the Accumulator is fine.

Thanks for the info on the ABS switch. Is there any way of testing that outside of the system? :)

My concern is that the guy I bought the car from has driven the car for a long time with this issue, I may be chasing the initial problem plus potential damage from continuously driving it. :(

SuperChicken89
06-05-2015, 03:07 PM
I'm sure there is a way to test the accumulator but have no idea how. From what I have read, the ABS pressure switch opens at around 2650 psi so the accumulator must hold at least that pressure.

I'm guessing the accumulator is your problem. At one time I had 3 or 4 used accumulators from junkyard cars and they all were bad. The accumulators have a nitrogen pressurized bladder internally. The bladders eventually lose the nitrogen charge due to a small hole and the accumulator is then bad.

Here is a good read on the Teves II system. http://www.35thatr.org/Tips/ABS.htm

Good luck.

Bryan

KMT
06-05-2015, 03:25 PM
One way to judge the health of the accumulator (assuming the system is ok otherwise) is how many pumps it takes to trigger the lights in the dash and make the pump run again.

Start by key on, noticing that the pump runs until the lights go out, then press/release the brake pedal )not fast/not slow, just enough for a full plunge, then foot off then repeat) and count.

It can take near 30 seconds or more for a good accumulator to recharge on first start after sitting overnight and then 5 ~ 8 pumps to trigger the lights and the pump motor. If you're only getting 1 ~ 3 pumps, you need another accumulator.

S_Mazza
06-05-2015, 08:37 PM
There is a tool for testing that and the accumulator, which is basically a tall steel pipe that screws into the MC, the accumulator screws into the top, and then a 3,000-psi gauge screws into the side. But it's expensive new, and rare used. You could use Kent Moore J-35604-88 and J-35604 together, or get OTC kit 7488A, which has some extra stuff in it.

Because of the rarity of this kit, the method of stepping on the pedal and seeing if the lights come on is usually a good first step.

The pressure switch sure could be bad. Or the accumulator.

Also, when you shut off the car, the ABS motor doesn't run then, does it? It should stop when the key goes off.

Rick_Leuce
06-10-2015, 04:46 PM
Because of the rarity of this kit, the method of stepping on the pedal and seeing if the lights come on is usually a good first step.

The pressure switch sure could be bad. Or the accumulator.

Also, when you shut off the car, the ABS motor doesn't run then, does it? It should stop when the key goes off.


The "Antilock Brake" light is always on and (according to the previous owner) has been for some time. The brakes do work (if they haven't been pressed for a while). The brakes get really hard if they have been used a lot in a short period of time (such as slowing down on an exit ramp then stopping at an intersection). If I'm driving the car somewhere that requires very little braking, then I can't tell that there is a problem.

I think I've heard that even if the accumulator is bad, the pump should eventually turn off. I've tried using the accumulator ball it came with, as well as another used accumulator ball and neither has caused the pump to eventually stop.

The accumulator pump can always be heard while the key is in the "on" position. The ABS pump will stop when the key is "off".

We're having the pump looked at and possibly rebuilt. I have a feeling that you may be right and that it could be a bad switch.

SCarSC
06-10-2015, 07:16 PM
Is your purpose to keep it functioning in stock form? Doing the conversion to standard brakes is much cheaper than a rebuild...like 60 bucks.

S_Mazza
06-10-2015, 11:45 PM
The "Antilock Brake" light is always on and (according to the previous owner) has been for some time. The brakes do work (if they haven't been pressed for a while). The brakes get really hard if they have been used a lot in a short period of time (such as slowing down on an exit ramp then stopping at an intersection). If I'm driving the car somewhere that requires very little braking, then I can't tell that there is a problem.

I think I've heard that even if the accumulator is bad, the pump should eventually turn off. I've tried using the accumulator ball it came with, as well as another used accumulator ball and neither has caused the pump to eventually stop.

The accumulator pump can always be heard while the key is in the "on" position. The ABS pump will stop when the key is "off".

We're having the pump looked at and possibly rebuilt. I have a feeling that you may be right and that it could be a bad switch.

Ok, thanks. The fact that the pump does turn off when the key is off means the ABS relay is probably working correctly. The fact that the brakes run out of assist quickly makes it almost certain that the accumulator is shot (and has been for a while). Now, just because that is bad doesn't mean the pressure switch is fine. But it may work fine with just a new accumulator ball.

The pump motor running all the time is certainly not good for the pump or motor. They do have a pretty good lifespan, but the motor brushes and/or seals tend to wear out before 200k miles under normal conditions. The motors are rebuildable. The pumps may or may not be rebuildable, but are almost always fine unless the fluid is badly neglected and left to sit. The actual master cylinder units are pretty complex and may not be rebuildable, but in most cases, they don't wear out.

SuperChicken89
06-11-2015, 02:18 PM
If I understand correctly from you orignal post, you own a 91 as well as the 90 you're having the ABS problem with. If this is the case, just take the good accumulator off the 91 and try it on the 90.

I believe from the information you have provided the problem is a bad accumulator. The most common problems with the Teves II ABS systems are with the accumulator, pump relay, pump, and pressure switch.

Bryan

Rick_Leuce
06-23-2015, 12:05 AM
If I understand correctly from you orignal post, you own a 91 as well as the 90 you're having the ABS problem with. If this is the case, just take the good accumulator off the 91 and try it on the 90.

Bryan

My dad originally wanted to borrow the accumulator from the 1991 just to test it, but we decided to use one from an old 1990 parts car instead. The accumulator ball on my 1991 is aftermarket (so it doesn't have the nice socket to ratchet it on and off like the factory ones). To install it, we had to epoxy a nut on top so that the ratchet had something to grip to. When we tried to remove it off of the 1991, the nut and epoxy popped off and we figured it wasn't worth the hassle of epoxying it every time we wanted to install and remove it (since we had already figured the accumulator ball on the 1990 was bad anyways).

The ABS assembly for my 1990 was remanufactured and just got mailed back today (with a fresh accumulator ball), so I'll try to reinstall it tomorrow morning. Hopefully that's the only thing left I need to do to make it safe for daily driving :)

sanddune24
06-23-2015, 12:13 AM
My dad originally wanted to borrow the accumulator from the 1991 just to test it, but we decided to use one from an old 1990 parts car instead. The accumulator ball on my 1991 is aftermarket (so it doesn't have the nice socket to ratchet it on and off like the factory ones). To install it, we had to epoxy a nut on top so that the ratchet had something to grip to. When we tried to remove it off of the 1991, the nut and epoxy popped off and we figured it wasn't worth the hassle of epoxying it every time we wanted to install and remove it (since we had already figured the accumulator ball on the 1990 was bad anyways).

The ABS assembly for my 1990 was remanufactured and just got mailed back today (with a fresh accumulator ball), so I'll try to reinstall it tomorrow morning. Hopefully that's the only thing left I need to do to make it safe for daily driving :)


If you decide you need to take it off you can try a strap wrench. I was able to remove mine with one.

S_Mazza
06-23-2015, 08:28 PM
The ultimate tool for removing the accumulator is an combo wrench, bent 90 degrees on the flat part, just far enough from the jaws that it will fit around the accumulator ball. Then you can use the closed end as a receptacle for a breaker bar and crack that accumulator loose with ease.

My accumulator wrench only cost me 1 ebay'ed wrench (~$10), because a nice guy at the local Pep Boys hit it with a torch and a sledge on his break for free.