Help!!!! 1995 Chevy Tahoe 1500 Unable to bleed the brakes

[Ahleebaba]

Greetings here is what is going on

• I received the vehicle with nonfunctioning brakes and cannot verify if air got into the ABS
• Pressure bleed the system numerous times with no success (5 times at least) – soft peddle once started and goes to the floor.
• The booster, master cylinder and slave cylinders have all been changed
• The semi peddle is firm when not running but goes to the floor once started
• I do not have a tech 2 scanner and the one I purchased cannot access the abs. Is the ABS bleed feature available on a 1995?
• You Tube makes it look easy but there is something I am missing
• I have all the tools and skills yet this is crushing me
• Any suggestions would be greatly appreciated

 

[wjburken]

Greetings here is what is going on

• I received the vehicle with nonfunctioning brakes and cannot verify if air got into the ABS
• Pressure bleed the system numerous times with no success (5 times at least) – soft peddle once started and goes to the floor.
• The booster, master cylinder and slave cylinders have all been changed
• The semi peddle is firm when not running but goes to the floor once started
• I do not have a tech 2 scanner and the one I purchased cannot access the abs. Is the ABS bleed feature available on a 1995?
• You Tube makes it look easy but there is something I am missing
• I have all the tools and skills yet this is crushing me
• Any suggestions would be greatly appreciated

I would try two things.

One, I would try and perform a vacuum bleed as that might help draw any air out of the system.

Second, you can try and do a “red neck” abs bleed by finding either a gravel road or a large grassy area you can drive on and when going 30-35 mph, “slam” on the brakes hard enough to engage the antilock brakes. This will cause the ABS module to cycle and help any air that’s trapped to move through. Do this a couple of times and then repeat the vacuum bleed and see if that helps. This method has worked for me on various vehicles that hVs a soft peddle after bleeding.

I am assuming the master cylinder was bench bled before installing and you are doing RR, LR, RF then LF when bleeding.

 

[Ahleebaba]

My worker bleed the master cylinder and installed it but I am not 100 convinced he got all the air out initially. I ended disconnecting the brake lines to the mc and did a second bleed and then plugged the ports and tested the system with engine running - firm peddle. Yester day we put it on jack stands and tried to run it but could get the 4wd to engage hence no front rotating. I do have a spot to take it to and do a road test/ abs activation which is what I will do.

I am still unclear if one can do the abs bleed via a scanner on this 1995 model. As for vacuum bleeding I have not had good luck with that in the past but willing to review. I have the pressure bleeder dialed in now but slow flow at 15psi.

Probably should take it to a shop but even the one I spoke with was skeptical... this is what happens when you do a job like this for free

 

[exp500]

Another Cheat is to cycle the key on/off once or twice while holding pressure on pedal. It cycles ABS once each time. Bleeding GMT400's seems to be a 2 Qt. minimum also, at least for me.

 

[Ahleebaba]

That is solid advise and will try - I am serious thinking of taking it to an empty lot driving and then slamming on the brakes. I have gone thru a gallon plus and i keep getting bubbles. I am going to try and key trick - much appreciated.

 

[Fless]

I am not very familiar with this body style but if the front calipers were replaced, make sure that the bleeders are on the up side, not down. Very easy to mis-install them left to right and vice versa.

 

[Ahleebaba]

I actually had the problem years ago when I was working on a Datsun 240z and put them on the wrong side. The napa autoparts guy figured it out for me so never again.

Cheers

 

[wjburken]

Another Cheat is to cycle the key on/off once or twice while holding pressure on pedal. It cycles ABS once each time. Bleeding GMT400's seems to be a 2 Qt. minimum also, at least for me.

They sure do get thirsty when I bleed them as well.

 

[east302]

Here are the pages from the 1995 manual. It sounds like they have a basic scan tool function that activates the system as part of a function test. On my 98, there is a specific menu in a tech2 for ABS bleed.

In the pressure brake bleed procedure, note that GM calls for the two pins at the end of the combination valve to be held down. They’ll have black rubber caps on them. Here’s one from a 96-98 Kelsey Hayes unit. I’m not sure if the TBI used the same one or not, but the combination valve is probably similar. There’s another pin at the opposite end.

When the brake is pressed, these pins will extend maybe 1/8” or so. Kent Moore sells a tool for holding it down - it looks like a money clip - but I’d bet the same results could be had by holding a screwdriver against them to keep them down.

It’s worth a shot. The manual continues with requiring an ABS function test which sounds like an automated brake bleed.

Also - if the drums aren’t adjusted then a soft pedal is a given.

 

[Ahleebaba]

It is all starting to come together or so it seems. I will read thru your reply which I truly appreciate. On the Kelsy Hayes unit I have only one bleed valve which now makes sense as there is no abs in the rear. From the you tube videos I have done the air purge but that did not solve the problem. I would love to print what you sent but not sure how to do it. I seriously cannot believe that a 1995 4wd tahoe with only front abs is getting the better of me. The only thing I come up with visa vie all great help is to cycle the abs with the key and to take it to an open area and have engage the abs.

Thank you so much for the effort and I will review the steps tomorrow. This is my first time on a board and I am pleasantly surprised at all the tech support.

Cheers,
Lee

 

[east302]

Good luck with it, the soft pedal can be aggravating on these. I edited my post above to ask how the drums looked. It sounds like you’re working on someone else’s vehicle and may not have the history of it, so if they’re out of adjustment then that won’t help the pedal.

 

[Ahleebaba]

Yes I am working on it and it is for my cousin. Stupid me thought it would be a simple brake job on a 95 Tahoe which has proven just the opposite. When I picked it up there were actually no breaks and had to use the ebrake to stop (3 mile distance to my house) which I attributed to a bad booster but it wrong. There is a good chance that someone worked on it and ran the fluid dry or my worker did not fully bench bleed the master correctly. I purchased a lot of new tools on amazon just to be down with this thing but no success so far.

As for the drums I have seen on you tube that air can be sucked in thru the slaves so I replace them and adjusted the brakes accordingly. Every time I do a new bleed I get air bubbles coming out and I have gone thru over a gallon of fluid.

Thank you for your input and hopefully you never experience an annoying project like this.

 

[wjburken]

Yes I am working on it and it is for my cousin. Stupid me thought it would be a simple brake job on a 95 Tahoe which has proven just the opposite. When I picked it up there were actually no breaks and had to use the ebrake to stop (3 mile distance to my house) which I attributed to a bad booster but it wrong. There is a good chance that someone worked on it and ran the fluid dry or my worker did not fully bench bleed the master correctly. I purchased a lot of new tools on amazon just to be down with this thing but no success so far.

As for the drums I have seen on you tube that air can be sucked in thru the slaves so I replace them and adjusted the brakes accordingly. Every time I do a new bleed I get air bubbles coming out and I have gone thru over a gallon of fluid.

Thank you for your input and hopefully you never experience an annoying project like this.

Have you checked to make sure you don’t have a leak somewhere?

 

[Ahleebaba]

I have not really checked but with that said I would be leaking break fluid if there were a leak and I am not. Per the internet it stated that the slaves could suck air so I changed them but I am not really buying that. Everything I am honing in on points to the abs which I do not have the scan too to activate. There is a bleeder on the side which I believe is really used when one changes a master cylinder to purge the air. It has crossed my mind that the ABS in some way is sucking air into the system yet it does not seem possible as it should leak when pressure is applied.

I am convinced if there were no abs I would have solid breaks and supported by guys who have removed them.

 

[east302]

Not sure that it would matter since its going to drop anyway, but GM specs a 20-25 psi startup when using the Kent Moore pressure bleeder. Also, here’s their diagram showing that clip on the combination valve during bleeding.

My 98 truck had a lousy pedal about ten years ago and I damn near put a “for sale” sign on it. It, too, was supposed to be a one hour effort. What a pain in the ass.

I accidentally fixed it when replacing the booster a few months later. I left the MC connected and tilted it down for clearance while I did the swap. I guess some elusive bubble found its way to the sky when it was jostled.

 

[Eman85]

First simple test. Buy 2 plugs that thread into the master cylinder then step on the pedal. If you don't have a rock hard brake pedal you have something wrong at the MC, most likely it's got air. You can pump and bleed all you want if the MC has air you're not going to accomplish anything. Just me but I always bleed the MC with 2 lines looped back into the reservoir. If I do it that way I never have air and never have a problem. Don't get caught up in all of the ABS magic, it's just a brake hydraulic system. Diagnose and save yourself a lot of wasted time and brake fluid.

 

[Hoesgottaeat2]

…I accidentally fixed it…

 

[Hoesgottaeat2]

Are the rear shoes adjusted properly?

 

[extra330]

newbie here. I have a 97 tahoe with an issue that began as a soft or spongy brake petal. When removing the rear hubs, it appeared both rear cylinders were leaking although not too bad. I replaced and bled both cylinders. Note that these were difficult to bleed as there was a very weak trickle of fluid. The soft petal got worse. I was able to resolve the issue finally by bleeding the cylinders again, bleeding the ABS check valve and replacing the master cylinder. In reading the forums, the brake issue appears to be widespread but not a lot of folks offering the solution that finally solved the problem. Hopefully this will help someone and I really appreciate this forum very much

 

[Bag4440]

I have a 98 Tahoe 4x4. I gravity bled my brakes. Make sure all visible leaks are fixed. Park on level ground. I took a clear tube to fit bleed screw then using a clear water bottle(clean n dry inside) add brake fluid to bottle. Enough where u can keep tube end submerged in fluid. Back up a moment and depress pedal several times and take off cap at booster and be sure it is full of brake fluid. Leave cap off. Go to wheel fartherest from booster. Should be right rear. Put tube on bleed screw. Also put a box end wrench on bleed screw first then clear tube to bottle. With end of tube always submerged in fluid bottle, simply crack open bleed screw and watch air and fluid flow thru tube. When air has stopped then tighten screw. Then onto next fartherest wheel from booster. It may take several times each wheel but gravity will work. U would check fluid level along way if u have a lot of air coming so u don’t put air back in system. Little aggravating but works well. It can be done alone is the big plus. Otherwise someone else could help and it would be much faster. Worked for me. Good LUCK.