Another Brake Question: 1994 w/ABS

[Chris_94]

I tried a couple searches and can't really find an answer other than "take it to a shop". Hoping somebody can tell me how to fix this myself. I'm handy, but not an expert. Been around cars my whole life. I'm just not real good with all the new electronic stuff, so I tend to buy and fix or maintain older cars. She drives the Explorer and I've been driving a 1994 Nissan Harbody 4x4 pickup since 1998.

I replaced the front calipers on my 1994 Explorer XLT. It has ABS. Bled the brakes the way you're supposed to do it. PR, DR, PF, DF - in that order. Bled all lines until new, clear fluid was running out. Took a quart, but we probably over did it. My brother worked the bleeder valves. I pumped the pedal and kept the reservoir full.

Get in it to drive and the pedal goes almost to the floor before the truck will stop. Won't really even pump up hard. During the test drive, we went a variety of speeds. If I slam on the brake pedal, I can hear and feel the ABS pump working. The system seams to be functioning correctly. But the pedal is soft. It stops amazingly fast, even from 65MPH. It stops fast from 25MPH and 40MPH. It's just the darn pedal is going all the way to the floor.

I started doing searches here and on google. There was a a guy that mentioend a tool, but I think he came to the conclusion the tools weren't available anymore. There was another guy that took the ABS system off his truck. I'm not opposed to taking the ABS off the truck, but I'd need some help from you guys.

We have another vehicle to use, so it's not an emergency. I just gotta get it fixed. Can't go campin', fishin' or huntin' until it's functional again.

 

[Jason94sport]

Doesn't sound like a ABS issue. More like a break problem. Still air in the system or a busted brake line or bad master cylinder.

 

[Chris_94]

I'm also starting to think maybe it's the master cylinder.

My wife was pumping the pedal for me a few minutes ago and she said it never feels like it gets hard. She said it's not pumping up. I got in the truck and tried to pump the pedal up to hard and it stayed spongey.

 

[Anime]

Just bleeding until the lines have new fluid in them isn't enough.

You need to use clear tubing so you can see the brake fluid as it goes out of the line and into the container. Look for the air bubbles. When there are NO more air bubbles, not even tiny little ones, in the brake fluid when it comes out, then the system is bled. Note you'll have to do this by bleeding each line only once or twice, then moving around to each line the same number of times. You DON'T just bleed one line several times until the fluid is new, then go to the others and call it good, if you do that, air and old fluid is still trapped because it gets pushed around to the other lines and never comes out.

It's just something you have to take your time with to do it right.

Still could be an old worn out master cylinder that went bad with new fluid that cleaned out all the gunk that was letting the old seals hold fluid, but you may want to save replacing it for the last resort if no amount of bleeding gets the pedal firm again.

 

[jd4242]

Sounds like air in the abs and that does require a special tool that isn't available anymore.some dealerships still have it.you sure you hear or feel the abs working? Old trick is to slam on the brakes on a dirt road or low traction surface.

 

[cgbier]

Check your Ford dealer. I was at ours today and asked if they have it. The service manager was scratching his head for a minute (I had to explain him first that my Mazda is a Ford), then mumbled "somewhere in storage maybe".

I have an appointment on Friday for a tranny flush.. I'll know more then.

If they don't have that tool anymore, then I might throw out the complete ABS system.

 

[arco777]

I had problems like yours when I did a disc brake rear axle swap. In the end I removed the relays and fuses for the ABS system, installed Dorman Speed Bleeders, and bled the system. Worked very well for me, just need to pull the ABS MIL bulb at some point.

 

[cgbier]

That sounds like a plan! Thanks!

 

[zekew64]

Also, with the older ABS-systems:

Look at the color of the fluid. A clear, slightly yellow fluid is considered "clean." Any kind of rubber particles, or a fluid that is black, contaminates the system and impairs braking performance.

Now, if you have a mulitmeter, you can check for too much water in a braking system. First, put the multimeter on a setting that allows you to read one-tenths volts DC. Next, put one probe into the fluid itself. Put the other probe against the master cylinder body. If you have a reading of 0.3 V, you have too much water in the system.

What most people don't understand, especially if they ask, "How did water get into my brake fluid?", is that the water gets into the fluid because of heating up and cooling down. Simple physics--when the brake system, in particular the lines, cool down, water condenses on the inside of the brake lines, and gets into the water that way. And after a long time of the heating/cooling cycle, the brake fluid starts to become black because the water, being combined with the fluid, starts to eat, acidically, the rubber seals in the system. The other side effect of water in the system is that under heavy braking, the water in the system "vaporizes," making the pedal go to the floor. It also keeps the pedal from being able to pump up, even with the vehicle off. When I did my rear disc swap, I had a throughly contaminated system--I cleaned out about 48 oz. of old, contaminated fluid from the system. As a result, my braking system was 100% improved, due to the clean fluid.

Also, check your vacuum hose leading to the booster. If that is old, cracked, or brittle, it won't allow the booster to pump up the pedal, due to the booster not holding vacuum.