Hi there, I have a 1999 Blazer LT s10 4x4. I decided it was time to change out my brake fluid as it was dark and was due for a change. I drained as much as i could with a sucker out of the reservoir, then bled from each line at each wheel while also filling the reservoir with new fluid so that it was never empty.
I bled til there was no air, which there was almost nothing from any line. I turned the car on, power assist came on, and my pedal more or less went to the floor. I bled again, no air anywhere but yet pedal has little to no feeling. I decided to switch out the master cylinder in case it was leaking, even though no fluid was shown to leak anywhere. Bench bled it, installed it, then bled each wheel again. Only one wheel let out the tiniest amount of air bubbles, almost not noticeable. Each time that I have bled each wheel, I did it almost 15 times per wheel. The method I have been using was the pump pedal hold routine. Done this many times in the past on many different vehicles.
I figured there must be some air trapped in the kelsey hayes abs unit, which I don't understand how as air was never introduced into it. I opened each outlet line of the 3 on the abs unit, and tried to bleed air out of it the same way as on each wheel with the pump hold method. No air what so ever, just perfectly clean clear brake fluid.
Where is the air? What is left? I have searched the forum relentlessly please help!

 

These master cylinders can be a royal pain to get air out of. If you are getting a little spout of fluid in the reservoir, there most likely is air trapped in there. I have a set of brake lines made up to use on these vehicles that loop the outlets on the master cylinder right back up into the reservoir as low in the res as I can get them and still put everything together properly. I install the master cylinder and just pump the brakes for what seems like forever.

 

Still no air, just used a master cylinder bleed kit, no air what so ever. Is it possible that the previous master cylinder and the brand new expensive one are both faulty? pretty rare i imagine.

 

I'm still betting that it is air in the MC. As I said, if there are little jets of fluid in the reservoir, air is most certainly still a factor in the MC. Just because you do not see any air come out of it, it doesn't mean that air still isn't causing your symptoms. Frustrating, I know, but better to find that it is something simple than to keep swapping parts.

 

here's a dumb idea , but i' ve seen it before. If someone replaced one or more of the brake calipers and installed it on the wrong side, the bleeder will point down so when u try to bleed it u will always get clean fluid out , but the air thats trapped will never come out. idk. good luck

 

swartlkk,

I just posted about a similar problem I'm having to this in a reply to another post.

I've got a 96 blazer 4x4 with rear drum & RWAL ABS (I'm pretty sure - I have only 1 main brake line going back to both rear wheels).

I had to replace the main rear brake line because it catastrophically failed on me. I've bled the brakes several times per wheel & it seems that there is no air coming out but I have little to no pedal. Actually I guess I do have pedal SOMETIMES. It feels that the pressure is building up Ok then suddenly it will go to the floor. While it is idling sitting still I have an "OK" pedal but as soon as I try to drive it the pedal goes to the floor & I have almost zero brakes.

Ok so those are my symptoms. Now my question(s):

You said that if there is a "jet" of fluid in the reservoir then it is likely air in the MC.

Do you mean there is a jet of fluid when you are applying the brakes or when letting off?

I'm getting the jet of fluid when I press on the pedal but (in my inexperience I guess) I thought that was normal.

To bleed the MC out you disconnect the brake lines at the MC & hook up temporary lines that flip up & back into the top of the MC? Do you have to make it so you can put the cover back on?

I haven't found any place that has the metric brake line flare fittings (haven't tried the dealer yet - $$). Do you know of a discount chain that has them?

I was reading a link from another thread to a service manual for a 91/92 & that said to not pump the brakes - like I've always done on every vehicle I've bled the brakes on - but just to slowly push the pedal down once & cycle the bleeder valve. Have you ever needed to do that to get these brakes to bleed?

Thanks in advance for your help.

 

I am experiencing the same symtoms you encountered. What did you end up doing to get your brake pedal back to feeling normal again?