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