causes for spongy brakes and brake solid lite?

[RedlineRex]

i have had a prob on my sy for a while where the brake pedal has been spongy and the brake light stays on. i have already rebuilt the master cylinder and it made absolutely no difference (i bled the brakes after the rebuild as well). i am no expert at brakes so maybe someone can chime in here. i'm thinking the problem could be the combination valve. i figure that if the prob was with the abs then it would throw an abs code (which it is not). i was also thinking that it could be the vacuum booster, but from what i read, that would make the pedal harder to press, rather than spongier... am i on the right track? i dont want to just throw money at the truck and hope that it fixes the problem... thanx!!

 

[Hu Ryde]

The light is probably on because you need to run the abs through diagnostics process to clear the code. It is a simple process by contacting 1 wire between terminal a and h on the aldl connector under the dash. It should moan and groan for a second then the code will be cleared.

As far as break spongy ness, that's usually air in the line and can be fixed with a good bleed job. HTH

 

[Blake]

Like Jesse said, bleed your brakes. All of them. DO NOT USE SYNTHETIC BRAKE FLUID. It will mess up your ABS. Just get regular DOT 3 or 4 and bleed them starting with the right rear and getting it cleared out till it looks new and then do the driver's side rear, then the pass side front and then the driver's side front.
My Ty's brake fluid looked like coffee when I bled it out. Took me almost 15 minutes with my wife helping.
A Sy or a 92 Ty will take longer because you actually have 4 long brake lines whereas the 93 Ty's only have one line going to the rear that splits off into two.
Hope this helps.
Blake

 

[RedlineRex]

thanx for the response guys. i will try to clear the code in a little bit. looks like i will need to attempt to re-bleed the brakes again too. now i'm getting a little curious though, how can air get introduced into the system when i didnt mess with the brakes at all? one day they were working fine, the next day (after a couple power brake boosted launches) it was all spongy.
also, on a side note, when i disconnect the wire connector on the combination valve, the light turns off. and there is slow pedal return after the brakes have been applied. does this point to anything else? after reading up brake troubleshooting in the manual, the only fix they list for slow pedal return is to replace the master cylinder.

 

[ed hess]

sounds to me like you blew the master cylinder and the sensor on the combo valve is telling you this. If the diagnostic chart lists this as the only cause, I would change that before i even posted.

ed

But what the heck do i know!
no response req'd

 

[RedlineRex]

thanks for the info ed. i had an idea the problem was in the area of the master cylinder, but since i already rebuilt it (as stated in the original post) and it made no difference, i was not sure it would need to be replaced again. i wanted to hear someone else agree with me before i throw more money at the truck and replace a good part. now i that i know which direction to head, hopefully my brake issues will be taken care w/o wasting any more $$ than i have to.
thanks for all the input guys!!

 

[Tydriver]

Also, my experience has been with a spongy/soft pedal.. If indeed that you are SURE everything is upto speed and operating advertised, then consider changing your flexible brake lines.. Again, this is only AFTER everything else has been checked, checked and then RE-checked.. Reason I mention this is, as the flex hoses age, they get weaker.. I replaced mine with Stainless braided on the rear (while doing a rear disk install) and the pedal firmed up nicely. Also, on another vehicle I swapped out to STAINLESS BRAIDED and I couldnt believe what a difference it made. Just a suggestion cuz the OEM rubber ones will swell under pressure in their later life...

 

[ed hess]

hmm
did you bench bleed the master cylinder before you put it on?

seemed to take forever when i bench bleed mine to get all the air out.

ed

 

[0-60N4]

Just a note on fluids; I don't think there is any problem using Synthetic brake fluid. It's the Silicone brake fluid that will cause a problem if it gets mixed with any regular brake fluid.

Synthetic should be better with a higher boiling point and less likely to attract moisture (there's a word for that).

Silicone would be good for a complete resurection of a collector car getting complete new brake lines, master cylinder, etc.

 

[MattGE]

Just to add to the fluid issue: Silicone compresses slightly under pressure, which can give it a spongy feel. Silicone also attracts and retains air more than polyglycol (Dot 3/4) fluids which makes bleeding harder. Dot 5 (silicone) also tends to outgas slightly just below it's boiling point, and has problems with seal wear and water accumulation and separation in the system. Therefore, it is not good in any ABS system.
The good things about silicone is that it has a very high boiling point and does not absorb water or mess up your paint :wink:

Stick with Dot 3 or 4

And never use an old bottle of brake fluid to "top off". If it's been sitting in your garage (especially if you're a florida sytyer), it will absorb all that humidity and give you a real spongy feel.

 

[Blake]

Thanks Jim and Matt. I meant to say "Silicone" not "synthetic".
I use Valvoline Synthetic DOT 3/4 brake fluid in mine. Gold bottle. Big bottle available at autozone. Good size for bleeding.
The Helms actually says not to use any brake fluid containing silicone for the very reason you have given.
Sorry about the typo. You guys are on it!
Blake