jhall Posted March 25, 2007 Report Share Posted March 25, 2007 Hi all, I've got a question related to a '96 GM G-1500 van with anti-lock brakes. I thought some of you knowledgable in brakes or anti-lock GM stuff might be able to figure this out. It has been pulling to the right for a while as brakes are applied initially, then brakes straight ahead. It's like a "tug" and then the vehicle brakes evenly. This was more annoying than hazardous. I originally figured the tug to the right was because the driver's side caliper was sticking and causing the passenger side caliper to engage first. On Friday, the driver's side front caliper locked and overheated the disk, pads, etc. Replaced caliper, disk, grease seal, etc. Caliper will extend OK, but found that it still will not retract properly. (Passenger side caliper works fine. ) Removed master cylinder, did a check and a bench bleed. It seems OK. Placed a C-clamp on the driver's side caliper piston and CAN NOT get it to retract even with the master cylinder lines disconnected. Just a dribble of fluid out of the line. Opened bleed screw on the caliper and the pistion can then be pushed back I've never seen this occur. Could it be the ABS module or is there a front end proportioning valve that might be plugged / damaged? Any help greatly appreciated. It's driving me nuts. Link to comment Share on other sites More sharing options...
JimD Posted March 25, 2007 Report Share Posted March 25, 2007 I would remove the rubber hose and see if there is something in there trapping the fluid. Should have said ...completely remove the rubber hose..... Jim Drive your car. Use your cell phone. CHOOSE ONE ! Link to comment Share on other sites More sharing options...
jhall Posted March 25, 2007 Author Report Share Posted March 25, 2007 I would remove the rubber hose and see if there is something in there trapping the fluid. Gave that option some thought also, but if the fluid goes into the caliper, I can't see why it would not return as easily. I'll pull it and see. One other note - when the brake pedal is pressed, there is a noise of hydraulic fluid rushing on the driver's side as the caliper pressurizes. It sounds like it's coming just behind the engine somewhere on the frame. Got a bad feeling it's gonna be expensive. Thanks! Link to comment Share on other sites More sharing options...
JimD Posted March 25, 2007 Report Share Posted March 25, 2007 There might be a piece of "something" in there acting as a check valve. And since it is a new caliper, you will be working your way backward toward the ABS valves and the master cylinder. Jim Drive your car. Use your cell phone. CHOOSE ONE ! Link to comment Share on other sites More sharing options...
adallak Posted March 25, 2007 Report Share Posted March 25, 2007 There might be a piece of "something" in there acting as a check valve. And since it is a new caliper, you will be working your way backward toward the ABS valves and the master cylinder. I agree with Jim. Something like that happened to me recently. But I inserted that "something" intentionally to plug a leaking line. The saddest thing in life is wasted talent Link to comment Share on other sites More sharing options...
Texas Jim Posted March 25, 2007 Report Share Posted March 25, 2007 I had a Caprice, that did something similar. The rubber line on the drivers side had a tiny piece of the rubber on the INSIDE of the line come loose and hang down acting like a one way valve. Fluid would flow TO the caliper, but not back the other way. It locked the brake on the drivers side. The wheel would slide. To get it home, loosened the bleed screw and tried not to use the brakes. Everytime you touched the brakes, you had to get out and loosen the bleed screw to relieve pressure. After getting it home, liked to have NEVER found the problem. I replaced the rubber line, bled BOTH front calipers and all was well. Link to comment Share on other sites More sharing options...
jhall Posted March 27, 2007 Author Report Share Posted March 27, 2007 I had a Caprice, that did something similar. The rubber line on the drivers side had a tiny piece of the rubber on the INSIDE of the line come loose and hang down acting like a one way valve. Fluid would flow TO the caliper, but not back the other way. It locked the brake on the drivers side. The wheel would slide. To get it home, loosened the bleed screw and tried not to use the brakes. Everytime you touched the brakes, you had to get out and loosen the bleed screw to relieve pressure. After getting it home, liked to have NEVER found the problem. I replaced the rubber line, bled BOTH front calipers and all was well. Thanks guys. I'll check and replace the left hand line before I get the big hammer out. I appreciate the guidance even though it's a non-caddy issue! I'll keep you posted Link to comment Share on other sites More sharing options...
Patrick7997 Posted April 3, 2007 Report Share Posted April 3, 2007 I agree with the posts here... how'd it turn out??? This might be slightly off topic, but when you replaced all this stuff on the driver's side, you also replaced all the same stuff on the passenger side, correct??? If you didn't... well, opinions vary I guess, but if I do anything to brakes, I do both sides, at the same time.... Link to comment Share on other sites More sharing options...
jhall Posted April 4, 2007 Author Report Share Posted April 4, 2007 OK, For those of you sitting on the edge of your seat waiting for this drama to end............ It was the brake hose. I ordered a replacement from the local parts place ( mistake #1, see below). I removed the hose and found that it was impossible to blow though it or even get brake cleaner to work through the "plug". I was very curious about the blockage. Ultimately I found that the internal portion of the hose had separated and was collapsing under pressure. I could stretch the hose pretty easily. Mistake #1 - When I attempted to reinstall the "D" block on the caliper, I found out why the aftermarket part was $60 cheaper than the dealer part. The banjo bolt would not thread into the caliper. On closer inspection, I noticed the "D" block was slightly larger than the one on the original hose and would not slide past the shoulder on the caliper. This may be mistake #2 - Went back to the store and ordered another replacement hose under the Bendix brand. Hope this resolves the problem. The first unit was made in Italy. It looked like they did not machine the "D" block to the correct size. I even had them pull a replacement caliper from the shelf to show them the misalignment. Oh yeah, they took notes and will report the problem to corporate so other stores can be alerted about the parts in stock- NOT. I hate it for the next guy that buys a replacement hose for his G1500. If this doesn't do it, I'm off to the dealer for a $97 hose (hosing is probably more appropriate ) Anyway. Getting this ready to sell this one. It's been pretty good and still runs great but has 150K miles on it. I use this for long trips and don't want any surprises while away from home. Found another van of the same model with the 5.3L engine in a 2005 model - same layout inside! Hope to see it this week. Thanks for the guidance on this guys!! Oh yeah, I will be replacing pads on both sides. Sloppy work means different lifetimes for the left and right pad sets!! Link to comment Share on other sites More sharing options...
JimD Posted April 6, 2007 Report Share Posted April 6, 2007 Good policy to replace the pads as axle sets. And I would also replace both front rubber hoses!!! Jim Drive your car. Use your cell phone. CHOOSE ONE ! Link to comment Share on other sites More sharing options...
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