Brake Problems on my 1997 S10 Blzer

[Mumbles]

I have a 1997 S10 Blazer 4x4 that is having some Braking Issues. I purchased the vehicle in March of 2011 and since then the Brake Pedal has felt a tad squishy at the top. I figured the system simply needed to be bled. The vehicle stopped fine, just required a bit more pressure on the pedal. I made a note of it, but didn't ever get around to bleeding it.

Fast forward to Monday. My wife, our son, and I jump in the Blazer to go pick up the wife's PT Cruiser from the shop where it was getting an Alignment done. As I back out of the driveway, I notice the !Brake!Park Light is on. Corissa (my wife) had been driving it that day while her car was down and stated, "Yeah, I can't seem to get the Parking Brake Light to go off. It came on just a little while ago." We hardly ever use the Parking Brake and the Brake Pedal felt way softer than normal so I knew the Parking Brake wasn't the issue.

I hopped out and looked under the SUV thinking I'd see Fluid leaking from a Wheel Cylinder, or busted Brake Line somewhere. Nope. Nothing. So I popped the cap on the Master Cylinder Reservoir. It was a bit low, but there was plenty of fluid and nowhere near what it would be if there was a leak. Mm...?

So we continue on to get the PT from the shop. Its about a 30 mile round trip. The !Brake Light is on the entire time and the Pedal is still very soft, requiring a lot of travel before you get any response. Once I get it back home, I pull it into my shop and notice a trail of Brake Fluid on the Floor. Check under the truck and sure enough a line running to the rear brakes is rusted and broken. "Ah-ha! There's my problem." Thinking I must have just missed it when I looked earlier, or the leak wasn't bad enough then to notice.

So yesterday I cut out the rusted/leaking section and replace it with some new 1/4" Line and refill the Master Reservoir. I ask the wife to run the pedal while I crack the Bleeder Screws. With the vehicle off she pumps the pedal and holds pressure. I start at the Passenger Rear and open the bleeder. A little fluid leaks out and I ask her if the pedal is on the floor. She says, "No, not yet." I ask her to press a little harder. And she states that the pedal won't go any further. Mm...? So I tighten the bleeder and move the the Driver's Rear. She pumps the pedal again and holds as I crack this side. Again a little fluid and then nothing. Again I ask about the position of the pedal. Corissa says that it hasn't moved. WTF? So I proceed to the Front Pass Caliper. She builds pressure and holds the pedal and I pop the bleeder. Fluid shoots out and the pedal goes to the floor. Same result with the Driver's Front Caliper. I move to the Rears to give it another shot, but get the same results. Pressure on the Pedal, but no fluid or air out of Bleeders and the pedal won't go to the floor. I tried starting the vehicle and pumping the pedal, which is still terribly squishy to the point of hitting the floor when the truck is running, then shutting it off and cracking the Rear Bleeders, but I still don't get any fluid or air out of either side.

I have pressure at the Front Brakes, but nothing from the rear, so my first thought is the that Proportioning Valve has gone bad. But before I go and tear that gnarly looking thing with 5 Brake Lines and 14 Wiring Connectors out of the engine bay I thought I'd ask for the opinion from others who have had a similar problem. I don't want to waste a bunch of time and money on a P-Valve when the problem may be something else. (Ie. Master Cylinder?)

So ladies and gentlemen, what do you think? Please post up with any thoughts, opinions, advice, or jeers. All are welcome.

My apologizes for the length of my post. I just want to be sure I am thorough and have provided all the information available at the present time.

[Mumbles]

I have performed a couple of searches and found a bit of info, but nothing definitive. I did find a post describing how the P-Valve makes the front brakes do the majority of the work, but the rear are what give you the firmness of the pedal. This is what my pedal felt like prior to this new issue. Soft at the top of the pedal, requiring more pressure to get a response. So again that points me in the direction of a faulty Proportioning Valve.

Also, throughout my searches I found information regarding a GM Tech "T-2" Brake Bleeding Tool. Here a post from the thread...

http://www.gmtruckclub.com/forum/sho...l=1#post307158

Am I really going to have to take my Blazer a Dealership or will I need to get one of these in order to properly bleed my system? Also, could not having used a T-2 Tool give me the issues I'm experiencing?

Would a tool like the one at the link below perform the same as the T-2 Tool?

http://www.amazon.com/Motive-Product...2856216&sr=1-7

Thanks.

[Mumbles]

Just a quick update. I checked the firmness of the Brake Pedal again while the SUV isn't running and the Pedal goes nearly to the floor. Running is the same, only the Pedal gets to the floor and more quickly than when the engine is off. I haven't tried driving the vehicle yet, but have placed it in gear while in the shop. The Blazer does stop, so I do have some brakes, but obviously they suck.

I did attempt to bleed the rears again using a MITYVAC. Pumping the pressure to 17-18 lbs, I did get more fluid from the bleeders, but not a lot and the amount of fluid in the Master Cylinder Reservoir didn't change. I also very slowly depressed the Brake Pedal with the Lid off the Reservoir and didn't see any fluid level change in the Front Section (for the Rear Brakes) of the Res. Both these facts tell me that I'm not pushing any Fluid.

One more thing I tried was to crack the Front Line between the Proportioning Valve and the Master Cylinder, while the Mityvac was attached to the Pass Rear Bleeder. I was wanting to see if I would get any suction from the line. Nothing.

I have a Parts Blazer of the same year that I'm going to tear the P-Valve off of to see what it takes to get it out of the engine bay. I have no idea if it's any good or not, but its worth a shot.

[Mumbles]

Having spoken about these issues with a friend, I've decided I may be over-thinking the situation. It could be as simple as having a blocked line going to the rear brakes. I could have a clogged metal line or a collapsed rubber line that feeds fluid to the Rear Wheel Cylinders. On my next day off, I plan to disconnect one of the fittings that holds the newly installed splice in the line to see if I can get any fluid out of it. This will tell me whether the problem is at the beginning of the Brake System or at the Rear of it.

I'll be sure to post up with my progress.

[dpeter]

Have you been able to get the brake light warnig to go off? I can't remember which car I had this problem in but I also had a rear brake line leak and as I recall there is a switch in the lines that monitors pressure on front and rear lines. If prssure is lost on one then a slide valve moves to block the bad line and moves a plunger of sorts that sets a switch to activate the light. This was a manual reset and required you to physicaly put it back. It had four lines to it and an electric connector and was located a bit under the master cylinder. I do not know if it was part of the proportioning valve or if it was a seperate piece. Let us know what you find and please don't drive it till you do! Good luck and BE SAFE.

[Mumbles]

Thanks dpeter. You are absolutely correct.

Behind a rubber cap on the Proportioning Valve there is a small plunger type deal that must be depressed to recenter a valve within the P-Valve in order to get fluid flowing to the portion of the Brakes that experienced the leak/lack of pressure.

My brother had some experience with one of these systems and lent a hand today. We were able to get fluid to the Rear Brakes, the System Bled, and the BRAKE(!)(P) Light to go off. My Pedal feels very good now when the engine isn't running and a little soft when it is. Similar to what the Pedal felt like prior to my busted brake line. There is probably a little more air somewhere in the system that could be bled out to give me a firmer pedal, but for now I'm happy with the results.

Thanks again to dpeter for posting up. I hope this thread can help someone who is experiencing similar problems in the future. I also want to say that I find it hard to believe that NO ONE ELSE on this forum had even the slightest knowledge of this valve within the Proportioning Valve that needed to be re-centered. Pretty weak guys.

[dpeter]

Thanks Mumbles but don't be to quick to judge the forum members, all in all it is a pretty good group and we just happened to be in the right place at the right time. Glad you got it fixed! Also need to mention that the closer you have the rear brakes adjusted the quicker the pedal will firm up too.

[Mumbles]

Thanks again dpeter. I guess this thread has only been up for a short amount of time, so it hasn't had a lot of time for people to see it. I mean no disrespect to the members here, but I am disappointed. The fact that Bleeding Brakes is such a simple and common procedure I would expect that any deviation from the normal process of pumping the pedal & cracking the bleeders to be common knowledge for a Forum such as this one.

[dpeter]

Hey Mumbles, your point is well taken. it does seem to me to be more of a "how my truck looks" site than technical sometimes but that is the beauty of this site, there are some pretty sharp people that seem to lurk around. You just never know when someone will have had the same thing happen and know what the fix is. As for me, I prefer function over form, I'll take it works good over it looks good every time.

[tbacachevylover]

I just replaced a broken line on the driver Rear of my 97 s10 and since doing so have not been able to return pressure to the lines. I have read your o
Posts but have no clue where this mystery value is located or how to reset it. Can someone please help???