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"New" brake caliper leaking from piston. Quick question. by MacGyversMullet
Started on: 01-21-2014 09:56 PM
Replies: 11 (4261 views)
Last post by: jb1 on 01-24-2014 02:42 AM
MacGyversMullet
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Report this Post01-21-2014 09:56 PM Click Here to See the Profile for MacGyversMulletSend a Private Message to MacGyversMulletEdit/Delete MessageReply w/QuoteDirect Link to This Post
So, I am finally finishing up my full suspension and brake replacement on the recent 86 I had bought. Long story short...the left rear caliper, piston and outer piston seal looked brand new when I bought the car and first took it apart, so I didn't replace the caliper. But somehow after the brake pad installation and full fluid flush/bleeding, a leak has developed from the piston. It dumps out a good amount of fluid from the piston and this didn't happen before...I wouldn't have made it 10 miles if it did this much before the fixing.

Do you think when compressing down the piston when installing the new rotors/pads, that the piston seal could have popped or mis-positioned itself? If so, is there a simple "backyard" fix to getting it to seal back up, without taking it apart? I will do a million things to a car, but I would rather buy a new caliper before rebuilding one. Just asking before I drop the $70 on another new caliper. Thanks!
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Report this Post01-21-2014 10:33 PM Click Here to See the Profile for trotterlgClick Here to Email trotterlgSend a Private Message to trotterlgEdit/Delete MessageReply w/QuoteDirect Link to This Post
If the bore had any rust or corrsion in it you may have pushed the piston down so that the seal is trying to seal on the rusted part of the bore. No easy fix. Larry
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cmechmann
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Report this Post01-21-2014 10:36 PM Click Here to See the Profile for cmechmannClick Here to Email cmechmannSend a Private Message to cmechmannEdit/Delete MessageReply w/QuoteDirect Link to This Post
No backyard fix without taking it apart. Most likely the square cut seal got cut when moving the piston in or was ready to give up already. Before doing anything you have to determine 2 things. First is the racket assembly for the ebrake still working ok. Second, is any fluid coming out of the vent port in the middle of the piston. Either of those, your replacing the piston anyway.
They are not really that bad to take apart. Look for an exploded diagram first if your not familiar. Search for GM rear caliper with integral ebrake rebuild. Lay out the parts in order. The rear seals and washers have to be in the right order.
The last thing you have to worry about is if the piston seal surface is pitted. If it is you cannot reinstall it. It will just cut the seal again. The pistons are getting harder to find/afford.
I rebuilt both of my rear calipers this past summer. (did the fronts in the spring) The right one had started leaking after trying to install pads. The piston was OK and I was able to install a new seal kit after cleaning some oxidation from inside of the bore.
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MacGyversMullet
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Report this Post01-21-2014 11:07 PM Click Here to See the Profile for MacGyversMulletSend a Private Message to MacGyversMulletEdit/Delete MessageReply w/QuoteDirect Link to This Post
Hmmmm...I figured as much, thanks guys. I can see how the rebuild could be easy, but these things seem kind of fussy to begin with, where precision is key. I will just drop the money for a new one, so I don't have to worry about it.
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Report this Post01-22-2014 08:05 AM Click Here to See the Profile for Fiero84FreakClick Here to Email Fiero84FreakSend a Private Message to Fiero84FreakEdit/Delete MessageReply w/QuoteDirect Link to This Post
I can tell you that some of the re-manned calipers out there are actually junk. The biggest issue is some of the things mentioned above. If the cylinder wall is pitted in any way, ultimately the caliper is junk. If the piston is pitted, then it's junk. If it is leaking out of the center vent port, the piston is junk. For a lot of re-mans out there, they're just disassembled, cleaned, and reassembled with new piston seals.

Last year I bought a re-manned caliper from the Fiero Store and the second I filled with brake fluid and began to bleed it fluid gushed out of the center vent port - like a faucet.
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MacGyversMullet
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Report this Post01-22-2014 11:28 AM Click Here to See the Profile for MacGyversMulletSend a Private Message to MacGyversMulletEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Fiero84Freak:

I can tell you that some of the re-manned calipers out there are actually junk. The biggest issue is some of the things mentioned above. If the cylinder wall is pitted in any way, ultimately the caliper is junk. If the piston is pitted, then it's junk. If it is leaking out of the center vent port, the piston is junk. For a lot of re-mans out there, they're just disassembled, cleaned, and reassembled with new piston seals.

Last year I bought a re-manned caliper from the Fiero Store and the second I filled with brake fluid and began to bleed it fluid gushed out of the center vent port - like a faucet.


Oh, I understand. It looks like everything out there is re-manned. So, it ultimately comes down to a roll of the dice when buying calipers for our car?
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cmechmann
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Report this Post01-22-2014 07:11 PM Click Here to See the Profile for cmechmannClick Here to Email cmechmannSend a Private Message to cmechmannEdit/Delete MessageReply w/QuoteDirect Link to This Post
The biggest issue with all the GM calipers with integral Ebrake is understanding the piston functions. Many assume they are the same as others with integral Ebrake and don't inspect the vent for fluid or clean with solvents that damage internal seals. (brakclean only when cleaning these pistons) Especially with removing debris from the rear screw/ratchet assembly. Petroleum based solvents in the rear can't be cleaned out afterwards due to solvents migrating into the screw assembly and attacking the inner seals. They cannot be disassembled. The Brakclean will evaporate. and only use brake fluid as a lube when reassembling.
I trust rebuilding them myself more than buying remans. You would do a better job of inspecting. With a new piston, would be better than most remans. We have seen some problems with a few remans. Besides the reuse of so so pistons, have seen a few over honed. Causing seals to blow out during a panic stop. I panic stop all work that has had a reman. Customers would be checking their underwear if it happened to them, not to mention the possibility of liability.
At work we normally use the Napa remans. Had did a set on a E350 2 days ago and at least they replaced the OE phenolic pistons with steel.
You may also want to check Epay. From time to time I see Delco remans. I would trust those and they would also install the updated pistons. If I'm not mistaken there was an update for the right piston on all GMs with integral Ebrake calipers that came out around 89 to deal with an Ebrake adjusting issue with earlier caliper pistons.

[This message has been edited by cmechmann (edited 01-22-2014).]

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theogre
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Report this Post01-22-2014 08:45 PM Click Here to See the Profile for theogreClick Here to visit theogre's HomePageSend a Private Message to theogreEdit/Delete MessageReply w/QuoteDirect Link to This Post
Did you rotate the piston? Then likely you wreck the seal.
IF that is true, can get a seal kit and maybe will fix it.

See my Cave, Rear Brakes

Many rebuild units a bad out of box. Try ordering at local AZ etc stores for this reason. Sadly, Common to return a few to get a good one.

------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)


The Ogre's Fiero Cave (It's also at the top and bottom of every forum page...)

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fierobug
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Report this Post01-23-2014 02:02 PM Click Here to See the Profile for fierobugClick Here to Email fierobugSend a Private Message to fierobugEdit/Delete MessageReply w/QuoteDirect Link to This Post
The 87 gt has original brakes (not pads) no leaks yet. Should I attempt to rebuild them even if they are not leaking before they get corroded or start leaking? Or should I wait - if it ain't broke don't fix it as the saying goes.

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FIEROBUG!!!!!!!!!!

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cmechmann
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Report this Post01-23-2014 07:23 PM Click Here to See the Profile for cmechmannClick Here to Email cmechmannSend a Private Message to cmechmannEdit/Delete MessageReply w/QuoteDirect Link to This Post
It would be good to go through the calipers to get the crud out to save the pistons. The only problem is if the piston is already pitted you won't know.
If the system has had regular flushes to get the moisture out, the piston are most likely OK. If not, it will be a gamble.
I can tell you on mine, at least the last 2 owners didn't service it. At least 6 years. And the system operation sucked. I went through all the calipers and lucked out with the pistons. I need to invest in better front pads. It has Wagners. But the system works OK for me. Ebrake works better. Stops better. Easier to service the pads. I'm most likely not going to upgrade the system after I do the engine/trans swap. It will only be about 80 lbs additional weight. Some I will be subtracting with gear reduction starter and removing the ignition cooler/hair drier assembly. I had to toss the OE wheels(not bent but curb rash) and went to a 16". I gained about 2 lbs for each rim but lost about 3 lbs in each tire. Went from a 215/60/14 to 215/55/16. Tried to keep the outside diameter close. Less sidewall, taller rim.
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MacGyversMullet
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Report this Post01-24-2014 12:45 AM Click Here to See the Profile for MacGyversMulletSend a Private Message to MacGyversMulletEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by theogre:

Did you rotate the piston? Then likely you wreck the seal.
IF that is true, can get a seal kit and maybe will fix it.

See my Cave, Rear Brakes

Many rebuild units a bad out of box. Try ordering at local AZ etc stores for this reason. Sadly, Common to return a few to get a good one.



No, I didn't rotate the piston. I pressed it straight in.

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jb1
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Report this Post01-24-2014 02:42 AM Click Here to See the Profile for jb1Click Here to Email jb1Send a Private Message to jb1Edit/Delete MessageReply w/QuoteDirect Link to This Post
I bought a set of calipers ( dual piston camaro) from brakeoverstock.com and had one leak. I am ordering new seals for it.... it happens..

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87GTseries 1 3800sc (7.597 @88.53 1.579 60ft)
(series II swap in progress)
85GT Northstar/ 4t80e
86GT 3800 n/a
Northstar Rebuild

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