Brake Repair mistake???

[Mattycallahan]

Today I changed by brake pads on my 97 k1500 as I've done before, except I forgot to take the cap off my brake resevoir before pushing the pistons back in. When I realized that I did not take the resevoir cap off and wen to remove it, I saw that it was wet where the master cylinder connects to the booster. Now with the new pads on, my brake pedal goes to the floor. Does anyone know if bleeding my brakes will fix my problem? Or did I blow out a gasket? It's dark now so I plan to look at it tomorrow morning. Thanks.

[brcidd]

I never take the cap off-- it should have a vent hole in it-it has to (otherwise it would not feed properly) so most likely, the fluid has pushed its way out the vent an drooled down by where you see it- should be no big deal- I assume the reservoir is full- a good indicator that it ran over.

All brake pedals will go to the floor after pad change- you need to slowly "pump them up" to get the pistons in the right spot- it may take several pumps- I never pump at full stroke though, I don't wish to put that master cylinder plunger in a place that it hasn't been before- due to posible corrosion that may tear out an o-ring or other seal. Heck, i know mechanics who put a 2x4 under brake pedal to avoid full stroking the master cylinder when replacing pads.

[j cAT]

Originally Posted by Mattycallahan

Today I changed by brake pads on my 97 k1500 as I've done before, except I forgot to take the cap off my brake resevoir before pushing the pistons back in. When I realized that I did not take the resevoir cap off and wen to remove it, I saw that it was wet where the master cylinder connects to the booster. Now with the new pads on, my brake pedal goes to the floor. Does anyone know if bleeding my brakes will fix my problem? Or did I blow out a gasket? It's dark now so I plan to look at it tomorrow morning. Thanks.

many do as you have done for years ...remove the fill cap push all the contaiminated brake fluid into the braking system..

when doing this with the front brakes this can cause damage to the braking components/seals.even sudden brake failure..

my proceedure is lossen the brake res. cap/cover.

then open bleed screw, using a C clamp slowly push the piston fully back then secure the bleed screw closed..

do one side at a time ..after pad install check level and bleed caliper../brake cylinder...

shoes have a small cylinder usually no big deal..front calipers very important to use this method ..esp. with ABS control !

new brake fluid compresses better !

[Mattycallahan]

No success yet. I've bled the brakes and replaced the master cylinder. Assuming that I bench bled the master cylinder correctly and then correctly bled the wheels RR RL FR FL, what else could it be? Could I have a bad brake booster? The pedal goes to the floor (somewhat slowly, not instantly)??? This half hour brake pad replacement job is nearing the end of its second day. Suggestions?

[j cAT]

Originally Posted by Mattycallahan

No success yet. I've bled the brakes and replaced the master cylinder. Assuming that I bench bled the master cylinder correctly and then correctly bled the wheels RR RL FR FL, what else could it be? Could I have a bad brake booster? The pedal goes to the floor (somewhat slowly, not instantly)??? This half hour brake pad replacement job is nearing the end of its second day. Suggestions?

pedal to floor is master or leak....

slow pedal to floor is usually a leak...be careful and using good light inspect these brake lines..especially the infamous brake line between the fuel tank and frame rail..


booster is hard pedal....no brake assist.........






It is possible ///very possible actually ...some have had the abs pump assy [internal leakage] cause your problem as well..they got a scrap yard unit to save some big bucks ...

[tblake]

Originally Posted by brcidd

I never take the cap off-- it should have a vent hole in it-it has to (otherwise it would not feed properly)

Are you sure about that? Better have another look.

The "cap" on this particular truck is in fact a large cover rather. It has a seal on the bottom half that is air tight. All brake fluid systems are air tight that I know of because brake fluid is hygroscopic. Hygroscopic meaning that it absorbs moisture. If there was a vent hole in your cap, your hydraulic brake system would literally rust from the inside out in a matter of about a month. Care to be a ginea pig? Remove the brake fluid resivor seal and drive it until you lose brakes. Lets see how long it takes.

[tblake]

Originally Posted by j cAT

new brake fluid compresses better !

I didn't know that brake fluid could compress. How is it that its able to transform motion from the brake pedal to our brake pads then? (if it compresses?). Just curious.

[tblake]

And lastly to the OP. sounds to me like you blew the seal at your master cylinder without removing the cap first. Buying a new master cylinder was a good idea because if fluid is leaking from between the vacuum booster and master cylinder, there is not supposed to be fluid there, so the seal in your master cylider has the be bad.

To me it sounds like it just might not be bled right. There is a ton of air that can get into these systems. I would crack all four bleeders open, fill the master cylinder to the top, leave the cap off for a little while and let them gravity bleed. Then close off all 4 and start bleeding the one farthest from the master cylinder. Right rear, then left rear, then right front, then left front. Do this a few times over in that order. Make sure you keep topping off your level after you bleed each corner or your'll gulp air and be back to square one. After you have a firm pedal, start the truck, and bleed them one more time with the help of vacuum assist. The you should be all set.

[Mattycallahan]

First I'd like to thank everyone for their input. I've now replaced both front calipers (the reason that I replaced them is because I bled all the brakes, but could not get all the air out of the RF and I was told that I may have broken a seal around the piston due to overly aggressive compression of that piston. I was then told if I replace one I should replace both. Last night I was able to get all the air out of the front calipers. Tbhis may be becasue of the new caliper, or becasue I improved my brake bleeding capabilities. The brakes are still squishy, so as I may not have bled the rear brakes properly the first time I am going to give bleeding them LR, RR, LF, RF one more try. This was also my first time bleeding a master cylinder (bench or any other way) so I may have introduced problems with that installation. If nothing better, I have a better understanding of my braking system...now only if I can get it to work

[tbeck3579]

Thank you very much for this post (I know it's an old thread, but it is still relevant). Due to my husband's disability I have been thrust into a role I find very challenging; car maintenance and repair person for the household. Personally I would much rather play "June Clever" and wear a pearl necklace with high heels but life throws us curv balls. Seriously though, in all likeleyhood this new found knowledge may have saved my life.

I was preparing the car for a 7,000 mile trip that involves driving in the mountains with steep grades. It goes without saying good brakes are an obvious necessity and not to be overlooked. I took my car in for new brake pads which, at first glance, seemed to be a relatively easy thing to do; a little research about brake pads, prices, a reliable shop, and done, OR NOT. Long story short, after leaving the repair shop (my third visit) I experienced a very serious problem with my brakes only two miles down the road. The shop had finally fixed my squealing breaks (long story). However, my brake peddle sunk to the floor at the traffic light. I immediatley knew this was very serious, and I knew this wasn't a problem before they "fixed" the rubbing/squealing/grinding "new" brakes that I had paid them to put a few weeks ago.

Anyway, the experience and knowledge I found here helped me to recognize exactly what had happened. I returned to the shop, and in my "this is what will happen manner" I explained the problem and what they will do to fix it. It was my "non-negotiable" voice, and not the "June Clever" voice they were accustomed to. Within a very brief period of time they fixed my car. Though they never admitted there was EVER a problem with my brake peddle, my car now has brakes that don't squeal/sqeak/grind and it has a brake peddle that will actually stop my car. Amazing how much effort and knowledge it took to get this done... Sigh

I suspect being an elderly female in a rural area where "older" men incorrectly assume women are an easy target (they forgot women can read now) played a significant role in this unbelievably dangerous saga... Thanks again, you're a lifesaver, literally! Please don't stop posting and don't stop asking questions. There are thousands of us who need this knowledge.