Ive got a 98 durango RWAL only.

The problem just happened today... Rear of the reservoir is low and the front is empty. Thought it was wheel cylinders... Nope. Theyre both fine. Pedal will go to the floor but the brakes are hardly doing a thing. No brake warning or ABS lights on on the dash. No leaks at the master cylinder or inside the truck at the firewall. No leaks in the lines anywhere that i can see nothing is cracked or rusted through. Anymore ideas? I read somewhere that a seal between the master and the booster could have gone bad and the vacuum is sucking brake fluid into the engine? I really don't know at this point but im trying to find it and fix it by tonight...
Thanks

 

If there is absolutely no chance it's leaking inside the drum from a wheel cyl, and no sign on the ground from anywhere, I fear your latter statement is very probable. IO have seen it happen personally at a shop I worked at. .

 

+1

Now you have air in the system which means your ABS is full of it. You will need someone to hook up to your ABS module to open the valves to bleed it. So I would say replace both the Master and the Booster if your sure there is no leaks and you’ve kept up on your maintenance. Then take it in and have the system bleed, but be aware that they have to hook up to the ABS which usually means dealer.

 

Thanks for all the help. We couldn't find any leaks so we rebled the system and put it all back together. Both wheel cylinders are for sure good. No broken or corroded or cracked lines anywhere. We have the idea that it could have been low to begin with and the brake shoe wear allowed it to get low enough that the fluid ran out. Im keeping a very close eye on it though incase the seal between the master and booster is infact bad. Strongly hoping that it was just pad/shoe wear though... Will keep posting with new information

 

Maintenance brother maintenance. I check all my fluids about every 2 weeks in my vehicles.

 

^^ yup. Doesn't the brake fluid reservoir have a low fluid sensor anyway though?

 

Well i generally check everything else pretty often. Didnt think about the brake fluid ever going low. Will be adding that to my check list. An no mine does not. I never got a brake or abs light on the dash which i thought was very odd. But thank you guys for your replies. If the fluid level keeps dropping, i will keep posting

 

There is no low fluid warning light that I know of. In short unless there is a registered issue with the ABS or proportioning valve I believe it won't register an issue.

 

I thought I remembered seeing some sensor on the side of the reservoir, but I guess it must do something else.

 

Good news and bad news. Good news is i figured it out. Bad news is its leaking out the back of the master cylinder on to the booster. So i guess im replacing a master cylinder this weekend.... Yay!... Gotta love old trucks.