Brake pedal goes to the floor.

[Suprapowaz!(2)]

We're looking at a 1991 7mgte and has ABS. My brakes went the floor a couple of weeks ago. I finally got around to taking a look at it. I automatically assumed the master cylinder is out, but I wanted to bleed the system first to get that possibility out of the way. I bled them in the proper order: passenger rear, driver rear, passenger front, driver front.
I ran into a problem. No brake fluid comes out of the driver front caliper. I removed the bleeder screw completely to see if anything would come out. Nothing. I took the caliper off and disconnected it from the brake line. Put the brake line in a cup and pump the brakes really good to see if anything comes out. Very little brake fluid comes out. About a half an ounce.
It seems like I have some kind of blockage. Could it be the proportional valve? ABS hydraulic unit? Is there any adjustment to the PV?

 

[hvyman]

Only a leak,air, or a bad master will cause it to go to the floor.

Does the passenger side bleed ok?
When you pulled the bleeder did fluid come out.

 

[S.A. supra]

Let me know what you need I have it all, since I went non abs.

 

[Suprapowaz!(2)]

The passenger side did bleed out good. Today I'm going to pull that caliper off, disassemle it, clean it out, and reinstall it.

Michael, I'll let you know. I definately need a master cylinder. It wouldn't be a bad idea to swap out the proportional valve as well.

 

[bioskyline]

if your getting much fluid on the one side, id inspect the lines and look for any kinks or leaks in the soft and hard lines.

 

[Suprapowaz!(2)]

That's what I'm going to do in a couple of hours here. I'm gonna blow some compressed air through each side of the line and see what happens. I'm thinking there some kind of blockage through the line somewhere.

 

[92ma71]

I would say you have a problem with your driver side front brake line. A piece of rubber line internally could be blocking it.

 

[Suprapowaz!(2)]

This is what I did today. I unhooked the line from left front caliper. I unhooked the line from the ABS hydraulic unit LF. I blew compressed air through the ABS side down. Brake fluid and crud came out and into the cup. I then blew air through the caliper side up. The remaining brake fluid came flying out of the line.
With the line still unhooked from the ABS I started pumping the brake pedal to see if fluid would come out of the ABS unit. It did. I hooked the line back up to the ABS unit and started pumping to see if fluid would come out of the line on the caliper side into the cup. I pumped the pedal, and not a drop came out.

What I'm going to do next is borrow my co-workers one man pump bleeder and see if it will pull any fluid to the caliper. I'll post result as soon as I can.

92ma71, you may be right. The rubber part of the line might be corroding from the inside and clogging up the line.

 

[hvyman]

Unhook the rubber line.

Tho generally a clogged line wouldnt make the pedal go to the floor. Iff anything it would make the pedal the same or harder and make the car brake to one side.

 

[Suprapowaz!(2)]

I'll do that tomorrow. I just came back from my friends to pick this up. http://www.sears.com/shc/s/p_10153_12605_00920930000P?prdNo=1&blockNo=1&blockType=G1

I'm going to go ahead and swap out the master cylinder soon. I'll post updates as a go along.

 

[Suprapowaz!(2)]

Ok. I found out it was the rubber line that's clogged. I disconnected from the hard line that goes into the firewall. Immediately brake fluid started dripping from the hardline. I hooked up the vacu-pump to the hard line and begain pumping. Fluid flows freely through it. There are two parts to the rubber hose. It's the lower rubber hose that's clogged.

Once I get it replace I'm going to properly bleed the system again. If pedal still goes to the floor, I'll change the master cylinder. Bleed again and see if that cures it. I'll let you guys know how it goes in a couple of days.

In the meantime I'm going to take off the rest of the calipers, remove the pistons, and clean the insides of them. The one that I did had some very dirty fluid in it. I'll take pics of the rest for show and tell.

 

[92ma71]

Well atleast you figured it out, hopefully atleast part of it. Glad to see your taking the time to go ahead and clean the other calipers too. Brakes are one thing you definately want to be right. Good Luck.

 

[Suprapowaz!(2)]

Thanks. So I went around the car tonight, took off the rest of the calipers, and cleaned them up. I only took two pics of one of the rear calipers. I didn't take anymore pics cause my hands were pretty dirty and I didn't want to touch the camera again. I think that black crud in there is from the rubber hoses. All of my calipers have that crap in them. I'm getting a feeling I'm going to have problems with my other brake lines being possibly clogged/collapsed.

 

[mk3_7m]

Pwoah. Well atleast you've found the problem now.


Time to do a brake line upgrade ??

 

[Suprapowaz!(2)]

Yeah, I'm thinking about it. I'll have to put that on my list, but it'll have to come later down the road.

 

[Typhoon]

The black stuff is just brake fluid that's broken down. Tine for four caliper rebuild kits and some new lines. Do it once and do it right.

 

[S.A. supra]

Sorry, rufus I needed my jack stands from darrell. I picked them up today Should have them down there mid week.

 

[Suprapowaz!(2)]

That's cool. I'm gonna help him out with his timing sometime next week.