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brake problems after pad swap


amo1dun
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89 4 wheel discs

 

Swapped pads in the front and now I have no pedal...compressed pistons back in ...went to pump them up and have nothing.....no leaks visible around the mc or at any lines......tried to bleed and rears bleed fine, fronts won't bleed will blip a lil fluid then air after multiple passes....I'm thinking I may have fudged the mc but not sure.........what should I start with.....already checked that booster is airtight...

 

Any sure fire way to test the master cylinder...?

 

If a calipers leaking should I see fluid on the piston cup seals?

 

Need some insight from the gurus.

 

 

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I've never heard of that issue. No leaks anywhere, the MC is full (enough) and all you get from the bleeder is air? Have you tried a gravity bleed? I'm not sure it will help but it can't hurt. Top off the MC, put a hose on the bleed nipple and into a container, open the bleed nipple and just let it sit for 15-30 minutes, checking to see if anything is coming out.

 

B

 

An afterthought, when you compressed the pistons back into the caliper, did you have the bleed nipple open? Nipple.

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I've never heard of that issue. No leaks anywhere, the MC is full (enough) and all you get from the bleeder is air? Have you tried a gravity bleed? I'm not sure it will help but it can't hurt. Top off the MC, put a hose on the bleed nipple and into a container, open the bleed nipple and just let it sit for 15-30 minutes, checking to see if anything is coming out.

 

B

 

An afterthought, when you compressed the pistons back into the caliper, did you have the bleed nipple open? Nipple.

 

 

No, i hav never had to bleed the brakes to swap pads..so all nipples were closed. ...

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Your "supposed" to clamp off the line and open the bleeder when compressing in the caliper (guilty, I rairly do that), any issues compressing in the calipers though? Did the pads compress onto the rotor at all when you pumped it up? You clean and lube the pad slides/contact points? How about the caliper slides? Cleaned and lubed as well?

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Your "supposed" to clamp off the line and open the bleeder when compressing in the caliper (guilty, I rairly do that), any issues compressing in the calipers though? Did the pads compress onto the rotor at all when you pumped it up? You clean and lube the pad slides/contact points? How about the caliper slides? Cleaned and lubed as well?

 

I should have been more specific from the start...

I swapped the pads pumped them up, still felt weak almost no pedal after a spin around the block...so thats when i started checking for leaks, pulled wheels to take a look at pistons ...seemed ok...then decided to try and bleed, dont see load sensing valve or anything like that, bled according to manual from right rear, left rear, driverside front,then pass.side.. the bleeder nipple on driver side front caliper was tight as a bitch so it took heat to loosen it...started the bleed process all over again, accordingly. now i have no pedal at all. pistons in the calipeers were kinda tight, but seemed ok.

pins are greased and fine ...rears bleed fine, fronts dont...

 

If I just bolt off the master cyinder ports i should have a firm ass pedal no?

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It sounds like you have a bad M/C. I would try to preassure bleed the entire system before replacing. When you pumped the pedal during bleeding, did you push the brake pedal all the way to the floor? I have ruined new M/C's by doing that. Have someone in the truck when bleeding and have them pump the pedal with 2 bleed screws partly open, but pump in shorter strokes, being carefull NOT to bottom it out on the floor.

Watch the fluid level in the resivoir, never allowing it to run dry and introduce air into the system.

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After doing this and watching for air bubbles coming out of the hoses on the nipples, repeat on the other 2 nipples openin one in front and one in back. Then close off all the bleeders, pump the pedal until it's nice and firm. Keep preassure on the pedal while cracking open one bleeder at a time, starting with the passenger side rear. Rotate around the truck bleeding each caliper at a time until you finish in the front drivers side. AND MAKE SURE THERES FLUID IN THE RESIVOIR AT ALL TIMES.

 

If the pedal is still soft after this. Change the M/C.

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tried bleeding again, definetely air in the mc when trying to bleed the front....maybe i blew a seal in the mc when i compresseed the pistons back in...idk

Edited by amo1dun
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tried bleeding again, definetely air in the mc when trying to bleed the front....maybe i blew a seal in the mc when i compresseed the pistons back in...idk

 

Is very possible...old seals maybe couldnt take the back flow.

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Pretty straight forward with a little bit of work. I'm glad it was that simple. :aok:

 

I'm chasing brake problems and it makes me consider just replacing the MC to get it out of the equation.

 

B

 

fyi, the best deal on a master i found that was in stock was advance ...if u order anything online thru nov30 and use promo code NV27, you get 15% off anyting over $50 and get $25 off a $50 purchase the next time....

i went with a cardone reman, and it was a oem nissan topico unit and came with 4 plastic bleeder nipples and hose (these m10 nipples can be a bitch to find in stock if u need them)

 

total price with core exchange was $65 plus the $25 promo i get back ...not too bad

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