ABS Failure? Cannot bleed at right front.
3rd Gear
Joined: Jan 2016
Posts: 3
Likes: 0
Abs pump rotted out, leakin fluid out the back
So, 86 c4, convertable, I guess the weep hole plugged up and filled the unit housing with water, sitting in 4" of water maybe caused the pump to fail, fluid leaks out of the rear of the pump center of the huge star bolt. I have no rear brakes. Can't seem to find a replacement at the dealer or any parts houses. Any ideas? Can I eliminate it...relatively easily? Your help would greatly appreciated! I'm in hawaii so junk yards are really not an option, nothing on ebay. Help help!
Instructor
Joined: Jan 2013
Posts: 163
Likes: 4
From: Perth WA
So, 86 c4, convertable, I guess the weep hole plugged up and filled the unit housing with water, sitting in 4" of water maybe caused the pump to fail, fluid leaks out of the rear of the pump center of the huge star bolt. I have no rear brakes. Can't seem to find a replacement at the dealer or any parts houses. Any ideas? Can I eliminate it...relatively easily? Your help would greatly appreciated! I'm in hawaii so junk yards are really not an option, nothing on ebay. Help help!
3rd Gear
Joined: Jan 2016
Posts: 3
Likes: 0
Team Owner
Joined: Sep 2003
Posts: 20,179
Likes: 673
From: Freedom is never more than one generation away from extinction.
St. Jude '03 thru '24
What I ended up doing was bypassing the ABS unit, I got some fittings & set the brakes up like any 'normal' car without ABS.
I did this so I could verify the operation of the brakes, I didnt want to replace the ABS unit until I knew without a doubt that it was the culprit.
I will replace the ABS unit, I am going this afternoon to meet a local guy who is parting an 88 vert, so I am hoping to get a package deal on a few things Im needing.
I read so many opinions on this issue, and many people want to say that the ABS unit cant cause your brakes to lock/rub etc. but I can assure you first hand - the ABS pump CAN cause brake failure.
However, I will state that the unit is unlikely to cause issues unless something foreign is introduced.
Mine has a valve stuck closed, not allowing any pressure to flow through the front right port. most likely caused by a master cylinder seal failure. junk pushed down the line to the ABS uint.
The orifices inside the ABS valves are incredibly small, and would be quite easy to block.
NOTE: If you want to try bypassing the ABS unit - make sure you get "Metric Bubble Flare" fittings. there are some that look the same, but if you use the wrong type of flare fitting they will not hold the pressure & could cause serious brake failure.
I did this so I could verify the operation of the brakes, I didnt want to replace the ABS unit until I knew without a doubt that it was the culprit.
I will replace the ABS unit, I am going this afternoon to meet a local guy who is parting an 88 vert, so I am hoping to get a package deal on a few things Im needing.
I read so many opinions on this issue, and many people want to say that the ABS unit cant cause your brakes to lock/rub etc. but I can assure you first hand - the ABS pump CAN cause brake failure.
However, I will state that the unit is unlikely to cause issues unless something foreign is introduced.
Mine has a valve stuck closed, not allowing any pressure to flow through the front right port. most likely caused by a master cylinder seal failure. junk pushed down the line to the ABS uint.
The orifices inside the ABS valves are incredibly small, and would be quite easy to block.
NOTE: If you want to try bypassing the ABS unit - make sure you get "Metric Bubble Flare" fittings. there are some that look the same, but if you use the wrong type of flare fitting they will not hold the pressure & could cause serious brake failure.
3rd Gear
Joined: Jan 2016
Posts: 3
Likes: 0
Thanks!
I found a used one in nc, cost way too much, 350$, but it came with the full harness uncut and it worked so the brakes are all working now. Thanks for your help. Good now on the flare fittings, I've heard people replacing lines with standard fittings and that's dangerous with the high pressure abs systems. Thanks again!
Advanced
Joined: Feb 2017
Posts: 86
Likes: 4
From: San Antonio, Fl Florida
Very good wright up
OK, if anyone wants to do this. here is the info...
Get 2 of these
http://www.appletreeauto.com/METRIC-...E-113-611-755/
You will need an extra caliper bleeder fitting. I replaced all of mine with speed bleeders so I had extra's.
1. Remove drivers seat (Not necessary, but VERY helpful)
2. climb in the car with a 12mm & a 15mm wrench, some paper towels, 2 'TEE' fittings & a bleeder fitting.
3. open your rear storage box & remove the black coated insulation peice.
4. remove the 2 hard lines from the passenger side of the ABS unit.
5. turn the bottom of the two lines up (vertical) and screw into one side of the 'TEE'
6.screw the upper line into the 'TEE'
7.screw the bleeder fitting into the third open port in the 'TEE'
8.Use the 15mm wrench to hold the 'TEE' fitting & use your 12mm wrench to tighten the brake line fittings & the bleeder fitting.
9. remove the 3 hard lines from the drivers side of the ABS unit.
10. twist the hard lines (gently) to line them up with the 'TEE' fitting and screw them in. (I chose to put the incoming line into the bottom of the 'TEE' then the 2 outgoing lines into the sides)
11. Use the 15mm wrench to hold the 'TEE' and tighten the 3 fittings with your 12mm wrench.
12. Disconnect the electrical connector with the one big red wire.
13. Put all the stuff back together, bleed your brakes (RF, LF, RR, LR)
Start the engine & put constant pressure on your bake pedal, making sure it stays in place.
If the pedal slowly sinks to the floor, then you have a leak.
FINE PRINT: This is bypassing your factory ABS, your car WILL NOT have ABS anymore, perform this at your own risk.
I only did this to verify that my entire brake system was performing properly before replacing the ABS unit.
It is NOT a permanent fix. unless its a track only car.
Get 2 of these
http://www.appletreeauto.com/METRIC-...E-113-611-755/
You will need an extra caliper bleeder fitting. I replaced all of mine with speed bleeders so I had extra's.
1. Remove drivers seat (Not necessary, but VERY helpful)
2. climb in the car with a 12mm & a 15mm wrench, some paper towels, 2 'TEE' fittings & a bleeder fitting.
3. open your rear storage box & remove the black coated insulation peice.
4. remove the 2 hard lines from the passenger side of the ABS unit.
5. turn the bottom of the two lines up (vertical) and screw into one side of the 'TEE'
6.screw the upper line into the 'TEE'
7.screw the bleeder fitting into the third open port in the 'TEE'
8.Use the 15mm wrench to hold the 'TEE' fitting & use your 12mm wrench to tighten the brake line fittings & the bleeder fitting.
9. remove the 3 hard lines from the drivers side of the ABS unit.
10. twist the hard lines (gently) to line them up with the 'TEE' fitting and screw them in. (I chose to put the incoming line into the bottom of the 'TEE' then the 2 outgoing lines into the sides)
11. Use the 15mm wrench to hold the 'TEE' and tighten the 3 fittings with your 12mm wrench.
12. Disconnect the electrical connector with the one big red wire.
13. Put all the stuff back together, bleed your brakes (RF, LF, RR, LR)
Start the engine & put constant pressure on your bake pedal, making sure it stays in place.
If the pedal slowly sinks to the floor, then you have a leak.
FINE PRINT: This is bypassing your factory ABS, your car WILL NOT have ABS anymore, perform this at your own risk.
I only did this to verify that my entire brake system was performing properly before replacing the ABS unit.
It is NOT a permanent fix. unless its a track only car.
front so I'm going to give this a try, the problem has to be in the ABS.
Its been a while since you posted this, are you still using the by pass or did you obtain a useable ABS system?
Race Director
Joined: Jan 2005
Posts: 10,641
Likes: 13
From: Slidell Louisiana
The ABS system is one of the reasons that I suck out the fluid in the Master cylinder using a turkey baster refill with fresh fluid and then flush the system every 18 months here in the swamp. Brake fluid absorbs water... DOT3 fluid is cheap... finding servicable 20 year old parts is *** pain...
I hate *** pain.
Mike
I hate *** pain.
Mike
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In that case, maybe ? People aren't mind readers, if you say that up front, then folks can constructively help.
Here is a good read on diagnosing/troubleshooting the ABS in your 86.
https://www.corvetteactioncenter.com...l#.UT4dfI6ubd4
There are also some threads that were recently brought back that discuss removing the ABS entirely
Here is a good read on diagnosing/troubleshooting the ABS in your 86.
https://www.corvetteactioncenter.com...l#.UT4dfI6ubd4
There are also some threads that were recently brought back that discuss removing the ABS entirely
Last edited by drcook; Oct 26, 2019 at 12:42 PM.
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