2001 Chevy S-10 brakes lock up while driving…

[2.2LFlexFuel]

I have a brake lockup issue where, after driving several city miles, pressure doesn't release off the brakes. They slowly start dragging, then really locking up. This ends up with super-hot rotors and wheels that stink to high heaven and an undriveable vehicle.

After letting it sit for an hour or so it seems to be okay but the problem reappears after several miles of driving.

My vehicle is a 2001 2WD Chevy S-10 with the 2.2L Flex Fuel engine.

The long story:

I bought this truck used in March with spongy brakes. It needed new pads and rotors, which I replaced. This July, to solve the spongy issue, I replaced the master cylinder.

While replacing the master cylinder I also cleaned the reservoir, which was filthy. It seems like my truck sat for quite some time before I purchased it. After attaching it to the new master cylinder, we installed it as per the instructions.

While bleeding the brakes, the braided steel line for the front brakes that goes from the proportioning valve to the ABS unit burst. It looked like a weak or rusty point in the line.

Since that part was dealer-only and the turnaround was four days, I had an industrial rubber hose company make me something comparable with similar diameter and PSI rating. For a third of the cost and having it that day, I was happy to install it.

That's when the brakes started locking, usually within five miles. I ran it without the ABS unit fuse with no difference. I also replaced the calipers and brake hoses since they were old and beat up, still nothing.

I also swapped in an identical ABS unit temporarily, thinking it might have been some debris in the sealed unit below the ABS electronics, but that did no good either.

While dealing with all of this, I found out that loosening the bolts on either of the front brake lines going out of the ABS unit lets off pressure and, assuming the works down around the wheels have cooled, lets me go another several miles.

At my wit's end, I took it to Midas (I know, I know, but it was closest). The manager there bled the brakes with his special machine they use for ABS systems, without any change. He insisted it was the proportioning valve and changed it.

When that didn't work he then replaced the front brake lines, one of which he claimed had a crimp and both of which he claimed were the wrong diameter, still without resolving the problem.

The last thing he did was to swap that custom rubber line between the proportioning valve and the ABS unit, which was for the front brakes, with the braided steel line, which was for the back brakes. I drove it all weekend, about 40 miles, without serious lockups though I still noticed slight drag and pressure at times. Next Monday morning, however, it was back to locking up after only a couple miles.

My thinking is it's the one-off rubber brake line I put on. So tomorrow I'm going to the dealer to order a new one. In the meantime I wondered what other folks thought of this.

In calling around talking to shops and talking to brake guys, I've heard a few other ideas:

• It might be debris in the line. But between me and the shop we've cycled over 1.25 gallons of brake fluid and have new lines in the front. How possible is this?

• It's the power booster that has a leak in its seal and actually sucks the wrong way as I'm driving. This doesn't make sense to me, though, since changing those brake lines between the proportioning valve and ABS unit temporarily improved things, and that would do nothing to or for the power booster.

• To check the brake pedal adjustment. As far as I can tell, there is none for the 2WD 2.2L Flex Fuel 2001 Chevy S10.

I've also had almost everyone tell me that the rubber line shouldn't cause a problem at all and that is has to be something else. Am I wrong to suspect it as the culprit?

Any ideas?

[Mudman88]

I had the same thing happen on my old 2000. I ended up rolling it because they locked up on an icy road.

[BernieB]

Just a couple of thoughts...

Flush the entire brake system and fill with new fluid, to eliminate any possibility of water absorption (lowering the boiling point which would cause steam in the lines and additional pressure).

Replace that rubber line with the proper steel braided one. The rubber one could be expanding like a balloon, causing residual pressure after you take your foot off the pedal. (Steel braid stops that)

Possibly bad calipers... but I'd expect that to happen all the time then.

Years ago a fellow mechanic told me about a weird problem with a Ford van. It probably doesn't apply here but I'll tell the story anyway, just in case... He'd replaced the front wheel bearings on an E-250 and right after that the front brakes started giving similar problems to what you describe. He went through much the same procedures that Midas mechanic did, replacing the proportioning valve, etc. It wasn't until he talked to a Ford factory rep that he found out what the real problem was... the front bearings were in too tight. It seems that Ford required a little runout (wobble) in the rotors to "kick" the caliper open. If the rotor was straight and true, and the bearings were tight, there was no wobble or runout and the calipers wouldn't release very far.

[2.2LFlexFuel]

I ordered the braided steel line from the dealer, $68 and some change. In the meantime I'm using a 14mm wrench to loosen the left and right bolts out of the ABS unit, which relieves the pressure and lets me drive, when the brakes get too tight.

If this doesn't do it, I'm going to replace the master cylinder. The one we initially bought and installed was a rebuilt one from AutoZone, which every local mechanic shop I've talked has sworn up and down is the problem--they all say Autozone sucks. I suppose I'll get a new one from Advance Auto if the steel braided line doesn't do it.

[leolkfrm]

Do you have a NAPA around you?

[gmctrucks]

I agree Auto Zone has nothing but trash it's not the first time I have a horror story about but here's one this guy had to replace his fuel pump three times before he got a good one I would have been super MAD. I would replace the master cylinder you bought from them and stay far away from them.
Good luck! GMC
PS-What about that check valve on the brake booster vacuum line.

[bradrhale]

i would bet money on the rubber brake line idea. these things have no life when people let the caliper hang by them. very bad for it and causing alot of the same symptoms you are experiencing.
while steel braids seem to be a better avenue, i have had great luck replacing them with standard rubber lines. unless you are 4 wheelin and tuggin at the lines a great deal, they should last you for a good while.

[2.2LFlexFuel]

Originally Posted by leolkfrm

Do you have a NAPA around you?

I have a couple within 15 miles. Would you recommend their remanufactured or new master cylinders over Advance Auto or Autozone's?

[2.2LFlexFuel]

Originally Posted by bradrhale

i would bet money on the rubber brake line idea. these things have no life when people let the caliper hang by them. very bad for it and causing alot of the same symptoms you are experiencing.
while steel braids seem to be a better avenue, i have had great luck replacing them with standard rubber lines. unless you are 4 wheelin and tuggin at the lines a great deal, they should last you for a good while.

The rubber hoses off the caliper are new, it's the front brake line from the proportioning valve to the ABS unit we replaced with a custom rubber line. I no longer thing that that's the problem anymore, however.

[gmctrucks]

Originally Posted by 2.2LFlexFuel

I have a couple within 15 miles. Would you recommend their remanufactured or new master cylinders over Advance Auto or Autozone's?

Leo im with you Napa has good parts as well. My dad knew this older GMC salesman down in south Texas his name was Leo well they would joke about him they would say he would tell the older ranchers buying new trucks that his line was that GMC & Chevy trucks were being made right by each other at the assemble plant and the parts that wouldn't fit they would throw them over to the Chevy assembly line so they could make them work so the ranchers would think oh GMC makes/has a better truck. Say this is a true story now I don't know if they believed him but he was one good salesman.
He! He! GMC