Brake Fluid Loss

[Gillah11]

Can anyone tell me how much brake fluid there is in a normally working brake system?

I seem to be losing it somewhere and can't find it OR the system takes a hell of a lot of fluid to fill up!

If I fill the resevoir to the required level I have normal braking pressure for the first 10-20 presses on the pedal, after that I lose all pressure and am back to putting my foot through the floorboard.

I can smell it from outside the cab after this happens but cannot for the life of me see it coming from anywhere, and with the rate I'm putting it in you'd think I'd be able to see it pouring out like an open faucet!

My original thought was just that the fluid had gotten way too low, but I think I've put in way to much at this point for it to still be low, unless that is these RRC's take an inordinate amount of brake fluid to run the system.

Any thoughts would be fantastic at this point, I'm at my end...

[Funrover]

Well..Did you bleed the system? You are sure you have 0 leaks? My guess is leak....... look all over first, check rubber lines first, then calipers, then master cyl area.... How does the pedal feel?

[troverman]

Check the steel lines that run parallel with or on top of the frame. (I haven't looked at our Classic line routing in awhile). The steel line broke on our '00 DII, frame gets wet but no real puddles. It goes through fluid very quick.

[stevo-II]

Maybe your master cylinder is leaking into the vacuum booster? That will fill up with fluid for a while and not show.

I just noticed you have a 1990 model - not sure if you have ABS or not - my comment was assuming that you didn't.

Steve

[rezdiver]

i agree with master leaking into booster. just changed mine for that reason, at your brake pedal, peel back the rubber boot on the piston and check the sponge and see if it is wet, also get some one to press on the pedal and stick your ear on the booster and see if you hear any sloshing. or just unbolt the master from the servo and look for fluid inside the servo and coming out the back of the laster, should be just two bolts for the master servo type.

[series1rangie]

Also any residual mud/dirt etc... could hide some leaks.

I had a similar problem where i had a dry rot leak up front, pedal was good then would slowly get worse. fill up reservoir, bleed, all good, get bad repeat. Even if the leak is not very noticible double check your flex hoses.

good Luck

Mike

[LANDY96]

Mine looked like it was loosing fluid too. I had to add a little to get it to full about every month or two. I still can't find where it is going, However i just looked at my level yesterday and it is over full! I don't know how and the hell that happened. Also is your brakes REALLY tight? I only have to depress the pedel like a 1/4 inch to get the brakes going. Everyone who had driven my truck is super impressed with the brakes!

[RageRover]

Definately there is a leak in the system. Just did the master cylinder in my mom's Mercedes 420 SEL, and it solved the problem. The rear primary seal on the primary piston in the Master Cyl. had just worn away because of age and use.

And yeah check all connections in rubber hoses, steel lines, etc. Does your RRC have ABS? If so, it could be the dump valves in the hydraulic unit are stuck open, but highly rarely does that happen all at once, as there are more than one valve.

[Gillah11]

Originally Posted by Funrover

Well..Did you bleed the system? You are sure you have 0 leaks? My guess is leak....... look all over first, check rubber lines first, then calipers, then master cyl area.... How does the pedal feel?

No, I'm not sure that I don't have any leaks, I just can't see them. It's very wet and muddy here right now so even after a good washing it's difficult to tell puddles of this from puddles of that.

A couple of you asked if I had ABS, and YES I do.

The pedal is really tight, or in other words doesn't go all the way to the floor, but that being said I have to press pretty hard to come to a full stop quickly. It also seems that if I pump the pedal a bit it builds up a bit more of a normal feeling to it.

I only hear the pump run when I've filled the resevoir and am turning on the vehicle for the first time after. Then it will stop, but start up again with EVERY push of the pedal. When the fluid is gone, it stops running.

A few weeks back I was sitting at a stop light with my foot on the brake as usual and all of a sudden I got a bit of "kickback" in the pedal. Then it stopped and the pedal went hard, and now it's been this way I've described ever since. (Until I fill the res. then it's good for 10 stops or so..., enough to get me home). Also the "brake" and "ABS" lights are on all the time now.

If any of the rest of this sounds familiar, or like something else you reckognize, please say. I'll check again all of the lines, calipers etc. and see if I can come up with anything concrete.

I'll also try all of the other suggestions as well...

Keep the ideas coming, thank you very much!