1991 S10 Blazer 4WD 4D

joetjohnson · 03-04-2008, 09:48 PM

I need to bleed my abs hydraulic unit. Where are the internal bleed valves located? What do they look like? Where are the accumulator bleed stems located? What do they look like? Thanks

**mack1** · 03-05-2008, 10:14 AM

Hi Joe
I have a 96 S10 blazer and its abs unit may be the same as yours. If so,
I've attached (i hope) a couple of pictures. One shows the abs unit with two large nuts on the back with a pin sticking out of each. Look under the pipes at the back (right side of picture). Those pins must be pushed in in order to get fluid to flow through the abs unit for flushing. The pins are hard to push in. I build a special tool to accomplish this (second picture). Notice the large nuts have a groove that will accept the tool with the bolt facing the pins. You may be able to get a strong friend to push them in (one at a time is ok) while you push in on the brake pedel.

Hope this helps.

Mack1

**Raylo** · 03-05-2008, 10:39 AM

Good info. I have a 1994 S10 P/U and a 1994 Camaro that have similar ABS units. I'll see if I can make a similar tool.

Here's another lower tech way to flush the ABS that might work depending on why you are wanting to flush or bleed the ABS in the first place. First, flush the brake lines putting in new fluid in the process. This is easy to do with a Mity-Vac setup or similar. Then go out and drive, preferably on a wet or snowy day, and engage the ABS by making firm applications of the brakes. This should get fresh fluid into the ABS and dilute whatever old comes out.

**mack1** · 03-05-2008, 12:46 PM

Hi Raylo
I made the tool out of a couple of large thin flat washers. Used piece of thinwall pipe for the body, you could get by with a couple of small stiff rods for the body. It really didn't have to be that strong. I could almost push the pins in with my fingers on the bolt. They seem easy with the tool, but hard to push in by hand.

Your method of flushing is better I think. My abs wasn't working, so it wouldn't work back when I tried it.

Have a nice day.

Mack1

cardoc · 03-05-2008, 05:01 PM

Hi everbody.
My question is why do you want to bleed the ABS unit to begin with.I agree with Raylo's method for home use.To bleed it properly really requires a TECH 2 scan tool to exercise all the gear driven valves.What ever you do don't force anything or let the master cyl.go dry.Then you start again from scratch.TRY this article similar to your systm.I'M not great at coping links but this gives the info. Good luck,Cardoc

http://napafix.com/hotline_forum_det...1&ROID=6747693

03-04-2008, 09:48 PM	#1 (permalink)
joetjohnson Registered User Join Date: Mar 2008 Posts: 1 OS: xp	1991 S10 Blazer 4WD 4D I need to bleed my abs hydraulic unit. Where are the internal bleed valves located? What do they look like? Where are the accumulator bleed stems located? What do they look like? Thanks

03-05-2008, 10:39 AM	#3 (permalink)
Raylo TSF Enthusiast Join Date: Feb 2006 Location: Maryland, USA Posts: 525 OS: XP Desktop, Vista HP Notebook, XP Notebook	Re: 1991 S10 Blazer 4WD 4D Good info. I have a 1994 S10 P/U and a 1994 Camaro that have similar ABS units. I'll see if I can make a similar tool. Here's another lower tech way to flush the ABS that might work depending on why you are wanting to flush or bleed the ABS in the first place. First, flush the brake lines putting in new fluid in the process. This is easy to do with a Mity-Vac setup or similar. Then go out and drive, preferably on a wet or snowy day, and engage the ABS by making firm applications of the brakes. This should get fresh fluid into the ABS and dilute whatever old comes out.

03-05-2008, 12:46 PM	#4 (permalink)
mack1 TSF Articles Team Join Date: Nov 2007 Location: Texarkana, Texas Posts: 1,245 OS: xp sp3 My System	Re: 1991 S10 Blazer 4WD 4D Hi Raylo I made the tool out of a couple of large thin flat washers. Used piece of thinwall pipe for the body, you could get by with a couple of small stiff rods for the body. It really didn't have to be that strong. I could almost push the pins in with my fingers on the bolt. They seem easy with the tool, but hard to push in by hand. Your method of flushing is better I think. My abs wasn't working, so it wouldn't work back when I tried it. Have a nice day. Mack1 Last edited by mack1; 03-05-2008 at 12:50 PM.

03-05-2008, 05:01 PM	#5 (permalink)
cardoc Registered User Join Date: Apr 2007 Location: Ct. Posts: 198 OS: win xp sp2	Re: 1991 S10 Blazer 4WD 4D Hi everbody. My question is why do you want to bleed the ABS unit to begin with.I agree with Raylo's method for home use.To bleed it properly really requires a TECH 2 scan tool to exercise all the gear driven valves.What ever you do don't force anything or let the master cyl.go dry.Then you start again from scratch.TRY this article similar to your systm.I'M not great at coping links but this gives the info. Good luck,Cardoc http://napafix.com/hotline_forum_det...1&ROID=6747693