No Brakes

[original]

After hauling a 3 ton load of junk to the recycling yard, I arrived home with no brakes. I haven't done much investigating yet. After de-salting the truck I pulled it into the garage. I noticed the brake light on and the pedal went to the floor. Front fluid reservoir was empty. No signs of any leaks. I did however, notice that the rear reservoir fluid was dirty. I'm going to remove the wheels and look around a bit. Either way I will flush and drain the entire system. Why does dot 5 brake fluid cost so much (22 per quart)? Any suggestions appreciated.

 

[Westech]

I pay 12 a quart from Autozone, its 6 bucks a pint. and I have no idea why you have no brakes.. if the fluid is low/out you HAVE a leak it does not just go away for the heck of it.

 

[wkbrdngsnw]

If it helps I believe the front one is for the front disk breaks so at least it narrows it to one end of the truck. Fix leak, bleed, prblem solved.

 

[goldneagle]

Maybe someone stole the brake fluid. If it is $22 per quart.

 

[Warthog]

 

[1986Blazerk5]

After hauling a 3 ton load of junk to the recycling yard, I arrived home with no brakes. I haven't done much investigating yet. After de-salting the truck I pulled it into the garage. I noticed the brake light on and the pedal went to the floor. Front fluid reservoir was empty. No signs of any leaks. I did however, notice that the rear reservoir fluid was dirty. I'm going to remove the wheels and look around a bit. Either way I will flush and drain the entire system. Why does dot 5 brake fluid cost so much (22 per quart)? Any suggestions appreciated.

I had a problem similar, but the gasket on the master cylinder was bad and every time i took a turn fluid would come out. i got to the point where it was so low that when i took a turn it would cause brake fluid in the master cylinder to slosh to one side and sucking in a air pocket, letting the brake pedal go almost to the floor. And if your fluid is dirty in the back this could be a problem.

 

[chevymike]

If it helps I believe the front one is for the front disk breaks so at least it narrows it to one end of the truck. Fix leak, bleed, prblem solved.

Actually that is not correct. Most all OEM systems use the rear reservior to feed the front brakes and the front reservior to feed the rear brakes. It has to do with the piston inside the MC. Most dual reservior systems apply the front brakes slightly before the rear, since weight is being transferred forward. Since the brake pedal rod pushes forward, the piston in the rear part of the MC gets moved first and then engages the front piston to apply the rear brakes. I know is sounds backwards. Even if you look at the line size the 3/16" line (common for disc brakes) is on the rear of the MC and the 1/4" line (common for drum brakes) is on the front of the MC.

Most likley you have a rear drum cylinder leaking. Hope that helps and good luck.

 

[ranchhopper]

Check the steel brake line that runs inside the passenger side frame rail they rust out just behind the cab usually at a point where it is affixed to the frame I replaced many of them always rusted in the same spot.

 

[1986Blazerk5]

Actually that is not correct. Most all OEM systems use the rear reservior to feed the front brakes and the front reservior to feed the rear brakes. It has to do with the piston inside the MC. Most dual reservior systems apply the front brakes slightly before the rear, since weight is being transferred forward. Since the brake pedal rod pushes forward, the piston in the rear part of the MC gets moved first and then engages the front piston to apply the rear brakes. I know is sounds backwards. Even if you look at the line size the 3/16" line (common for disc brakes) is on the rear of the MC and the 1/4" line (common for drum brakes) is on the front of the MC.

Most likley you have a rear drum cylinder leaking. Hope that helps and good luck.

I thought that the brake combination valve controls this? It is located on the crossmember by the radiator.

 

[davidkroberts]

I think that is a proportioning valve and doesnt have much to do with the rear brakes. When you were looking around and could you see anything leaking from the rear of the wheels. sounds like a rear wheel cylinder or line gave out.

 

[chevymike]

I thought that the brake combination valve controls this? It is located on the crossmember by the radiator.

Well, actually it depends on the system and I made more of a general comment versus a specific to this generation GM vehicle. Some systems put the valve into the MC (two pistons with a spring) and some on in a combo valve. Both ways basically work the same but the combo valve also has a switch that if you lose fluid in one end of the system, it kicks the "switch" on to light up the brake warning light on the dash.

Sorry for not specifying this as a general comment in the beginning. The fun ones are some late '60 GM systems that also had a stand-off valve that would dampen the spike of someone jumping on the brakes really hard and locking up the rear wheels. It was like a pressure relief valve.

 

[original]

I have look the truck over every inch. No leaks. No rust on the truck. I took a clean white towel and wiped the brakes lines from the master cylinder to the whell cylinders. No fluid just a little dust. I have examined the brake control valve. I dont see any leaks there either. I've just never seen fluid disappear. The MC cover and seal don't leak. Before this I had trouble pushing the brake pedal with my gimp leg. I'm just going to drain the system and replace all wheel cylinders. I would rather have to replace all the lines then deal with a unkown reliability problem. My father worked for GM I have heard him speak of testing and installing the combination valve. I'm just going to have to rebuild the brakes from the begining. I cannot tolerate an unreliable brake or any other system. I'll keep my results posted. I've got to install a fuel pump in a rust bucket ford explorer today. Maybe I'll get started on the brakes tonight. Thanks for all your answers.

 

[porkysplace]

The larger of thr 2 reservior's is for the front brakes . It allows for extra fluid needed to allow for pad wear ,as pads wear more fluid is retained past the check valve to keep the piston and pads in contact with the rotor . The cover gasket has the expandable part to compensate for the lower fluid level .

So if only one reservior is empty the part of system to check
large side empty look for leaks in the front
small side look for leaks in the rear
you may also want to pull the 2 bolts on master to see if shaft seal is leaking

Your mention of having a hard time pushing the pedal could indicate the master is leaking into the booster damaging the booster

 

[davidkroberts]

yeah okay that is wierd. not a big surprise though about the time you think you have these things figured out then POW.... not so much

 

[original]

I found the leak. The brass tee above the rear differential had a slow leak. the differential casing absorbed all the fluid. After setting in the garage for a few days I wondered why the differential hadn't dried yet. I replaced the all the lines from the proportional valve to the wheel cylinders. I drained the entire system and refilled. Brake fluid was very dirty and I'm sure it was a mix of dot 3 and 5. I replaced all with dot 5. I would suggest that everyone checking the fluid in the master cylinder. Mine looked fine at the top, but the bottome was a mix of dirt and water. The lines were also filled with this mess. I wonder how I had any brakes at all. A complete flush and refill makes me feel a little safer. I wish I could post a picture of what i flushed out of it.
Dial up internet is the only thing available in my middle of nowhere area. 2o minutes to upload one picture.

 

[doghead]

Does anyone know if the Tee he mentioned is actually brass or steel? I didn't think brass can take the pressure of the brake system. Just asking...

Are you talking about an M1008 or M1009? Did you replace the rubber flex brakeline on the rear?

 

[porkysplace]

DH , I'm pretty sure they are brass OEM , I don't see why brass wouldn't handle the pressure the banjo fitings on the duece are brass and handle it .

 

[rnd-motorsports]

If its OEM would be brass! and most manufactures recommend to change and flush the brake fluid in most all cars and trucks!The issue with brake fluid is that it absorbs moisture. When this moisture laden fluid is in the caliper, the heat generated can cause it to boil. Most people don't use there brakes that hard, but if you drive in the hills or tow something, this situation can come into play.Thats why dot 5 came to be its a silicone fluid others are a glycol fluid the silicone will stand up to heat way better came to be because of racing apps.and will not attract moisture as much as glycol the down side to silicone fluid is it aerates very easy (will not take shacking) silicone is also more compressible then dot 3 pedal will not be as firm and does not change color to show the moisture for that reason making the system using it more susceptible to corrosion! also be careful not to use it in any anti lock brake applications as the lack of lubrication for valves and such in the anti lock systems just for info check it out yourself

 

[original]

The tee fittng is definitely brass. The holes one each side for the rear lines were too big. I guess over time the fittings had worked loose in the brass. They wouldn't tighten sufficiently. I replaced the assembly with a universal one from Parts R Us (home of the smokin deal). Longer rubber hose and steel tee fitting. 85 M1008

 

[Hoolio]

A couple of brisk pumps on the brake pedal will show where it's leaking.. Front reservoir is for rear brakes , rear reservoir is for front brakes as Chevymike said..