flash Posted March 28, 2007 Report Share Posted March 28, 2007 i have a 98 deville and since new the front brakes have made noise the rotors have been turned many times and now have been replaced i have installed new rotors -pads-calipers and they still make a scraping sound Today i removed the ABS fuse and it has helped slightly The only things i can think of now are a proprtioning valve and a new master cylinder ANY ideas of how i can fix this flash Link to comment Share on other sites More sharing options...
kev2 Posted March 28, 2007 Report Share Posted March 28, 2007 So many questions ....sorry Can you describe the noise, Are you the origional owner? How many miles, AND how many miles between brake pads & rotor turnings? Have you run the diagnostics, tires are STOCK size, there are no modifications or add on's. I see a TSB for "grunting, groaning, grinding, squealing" brakes but corrective action is to replace rotors .....which you have done... Link to comment Share on other sites More sharing options...
gatyo Posted March 28, 2007 Report Share Posted March 28, 2007 ...installed new rotors -pads-calipers... Today i removed the ABS fuse and it has helped slightly... The cheap... You have not mentioned brake hoses. They might look fine from the outside but their inner walls could collapse and form sort of a check valve. When the brakes are applied, the pressure is great and it pushes through brake fluid; however, when the brakes are released, back flow can be resrtricted leaving a residual pressure in the caliper(s). The expensive... We have heard on this Forum that a sticky/failing ABS Pressure Modulator Valve can lead to spongy brakes, so it is not inconceivable that it can also result in "dragging" brakes. You may want to try to have the PMV bled by the so called Auto Bleeding procedure which involves the Tech2 tool (dealer?). It is basically pressure beeding from the Master Cylinder while exercising the ABS functions by the Tech2 tool. A DIY version of this is to find a deserted gravel road (or a rainy day) and give your ABS a nice work out. The PMV *is* expensive! Link to comment Share on other sites More sharing options...
JimD Posted March 28, 2007 Report Share Posted March 28, 2007 .... A DIY version of this is to find a deserted gravel road (or a rainy day) and give your ABS a nice work out. Followed by a thorough flushing with fresh fluid. I might have missed it in the posts, but have the caliper slide pins been checked / cleaned / replaced? Jim Drive your car. Use your cell phone. CHOOSE ONE ! Link to comment Share on other sites More sharing options...
stsjoe Posted March 28, 2007 Report Share Posted March 28, 2007 Probably a dumb question but have you checked the dust shield for contact? Are you sure it's not the back end (press the parking brake when the noise happens) Link to comment Share on other sites More sharing options...
nigel Posted March 28, 2007 Report Share Posted March 28, 2007 if the fault has been there from new, way back in '98, most of the common wear and tear causes such as weak brake hoses and contaminated fluid probably can be ruled out. it sounds like an assembly fault. it appears like the front brakes are not fully releasing. my sts suffered from a faulty abs modulator valve that gave the spongy pedal feel, eventually leading to the front brakes locking on when an internal valve completely stuck. the abs pump cycles at about 5mph, pumping up the system and performing an internal electrical check. of course, using tech 2 to activate the auto bleed sequence properly indentified the problem when the mechanic correctly carried out the abs bleed and tests as detailed in the fsm. incorrect pedal travel, incorrect brake light and cruise switch adjustments and wrong operating rod clearance can lead to the master cylinder not fully returning. with the front of the car raised and supported, selector in N, do the wheels turn freely? if the wheels are hard to turn, do they spin easier after cracking open the bleeder valves and do you get a spurt of fluid? if so, then the brakes are pressurized and they shouldn't be. pump the brakes back up then you could try loosening the master cylinder from the booster. if that makes the wheels spin freely then the problem is pedal/switch/rod adjustments. if the wheels are still stiff then look to a faulty abs pump, get a tech 2 abs check carried out. in truth, your dealr should have sorted the problem a very long time ago. you cannot properly bleed the abs system without tech 2 and the fluid should be changed about every 2 years as part of routine servicing Link to comment Share on other sites More sharing options...
flash Posted April 9, 2007 Author Report Share Posted April 9, 2007 if the fault has been there from new, way back in '98, most of the common wear and tear causes such as weak brake hoses and contaminated fluid probably can be ruled out. it sounds like an assembly fault. it appears like the front brakes are not fully releasing. my sts suffered from a faulty abs modulator valve that gave the spongy pedal feel, eventually leading to the front brakes locking on when an internal valve completely stuck. the abs pump cycles at about 5mph, pumping up the system and performing an internal electrical check. of course, using tech 2 to activate the auto bleed sequence properly indentified the problem when the mechanic correctly carried out the abs bleed and tests as detailed in the fsm. incorrect pedal travel, incorrect brake light and cruise switch adjustments and wrong operating rod clearance can lead to the master cylinder not fully returning. with the front of the car raised and supported, selector in N, do the wheels turn freely? if the wheels are hard to turn, do they spin easier after cracking open the bleeder valves and do you get a spurt of fluid? if so, then the brakes are pressurized and they shouldn't be. pump the brakes back up then you could try loosening the master cylinder from the booster. if that makes the wheels spin freely then the problem is pedal/switch/rod adjustments. if the wheels are still stiff then look to a faulty abs pump, get a tech 2 abs check carried out. in truth, your dealr should have sorted the problem a very long time ago. you cannot properly bleed the abs system without tech 2 and the fluid should be changed about every 2 years as part of routine servicing if the fault has been there from new, way back in '98, most of the common wear and tear causes such as weak brake hoses and contaminated fluid probably can be ruled out. it sounds like an assembly fault. it appears like the front brakes are not fully releasing. my sts suffered from a faulty abs modulator valve that gave the spongy pedal feel, eventually leading to the front brakes locking on when an internal valve completely stuck. the abs pump cycles at about 5mph, pumping up the system and performing an internal electrical check. of course, using tech 2 to activate the auto bleed sequence properly indentified the problem when the mechanic correctly carried out the abs bleed and tests as detailed in the fsm. incorrect pedal travel, incorrect brake light and cruise switch adjustments and wrong operating rod clearance can lead to the master cylinder not fully returning. with the front of the car raised and supported, selector in N, do the wheels turn freely? if the wheels are hard to turn, do they spin easier after cracking open the bleeder valves and do you get a spurt of fluid? if so, then the brakes are pressurized and they shouldn't be. pump the brakes back up then you could try loosening the master cylinder from the booster. if that makes the wheels spin freely then the problem is pedal/switch/rod adjustments. if the wheels are still stiff then look to a faulty abs pump, get a tech 2 abs check carried out. in truth, your dealr should have sorted the problem a very long time ago. you cannot properly bleed the abs system without tech 2 and the fluid should be changed about every 2 years as part of routine servicing i have a 98 deville and since new the front brakes have made noise the rotors have been turned many times and now have been replaced i have installed new rotors -pads-calipers and they still make a scraping sound Today i removed the ABS fuse and it has helped slightly The only things i can think of now are a proprtioning valve and a new master cylinder ANY ideas of how i can fix this flash ===================================================== i have done about everything suggested here i think except giving the ABS a workout the slides have been checked and replaced also Since tking the fuse out i do also notice harder steering also and the ABS traction control light is on now too This has been just about the only complaint since new on this car i sure hate to get rid of it because of the brake problem but i HATE driving down a road and having it sound like a junker with the brakes squeeking as they do Link to comment Share on other sites More sharing options...
BodybyFisher Posted April 9, 2007 Report Share Posted April 9, 2007 I am not sure if you have the rubber bushings in your calipers but if you do replace them with new ones, and use ONLY the GM brake caliper grease. Make sure the caliper slides easily on the sliders. When you replace them, remove all debris under them like rust etc. While you are doing that job check to see if your caliper piston depresses easily into the caliper you might have scored pistons or swollen seals.. Bleed the entire system make sure you are using the CORRECT DOT spec, if you have water in your system it will boil. Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
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