Can I change my master and bleed it on the car without a Tech II? My master seems to have a very small leak at the area where the two halves meet. Anybody ever see this? What are my options for bleeding the brakes after changing a master?

 

Photos of leak attached.

 

bump

 

You might be able to get away without a T2. The T2 is for bleeding the ABS. Here's what I would try:

1. buy some part# BQ164 caps. This is the cap that will seal off the brake lines that connect to the MC. Get 4, they are handy if you ever need to cap off the lines at the calipers too. If you GOOGLE BQ164 several sources will come up.
2. Get as much fluid out of the MC as you can, to limit the mess. Get some 30cc syringes at Tractor supply or some other farm supply store for this.
3. Take the lines off the MC one at a time. Immediately put a BQ164 on the line you remove.
4. Disconnect the rest of the stuff, R&R the MC.
5. Say a short prayer you don't need a T2
6. Fill MC, Bleed brakes at the calipers as usual.

 

You should be able to change the reservoir while it's on the car. Suck the fluid out with a suringe and then I think there's a roll pin that holds the tank on. Take that out and try to pry the tank off. Once it's off replace it and refill, no bleeding should be required.

The fluid looks pretty bad. Might be a good time to flush the system though.

 

Yea his fluid is pretty discolored. The GM parts list shows the master and reservoir as one piece, not sold separately. Maybe Dorman or Centric sells aftermarket plastic reservoirs, I dunno.

IIRC, the reservoir has two separate ports, so it may be two roll pins. Last time I did it, changed the whole MC when my reservoir cracked.

 

Would like to hear more about just removing the reservoir. Thanks for the input.

 

Why would you need a tech 2 to do a master cylinder?


I just did my master and braided lines. Removed, installed and bled like any other car.

 

only if you drain the lines and have air in the ABS lines. Also, looking at the OP's master, the fluid hasn't been changed in a long while, and that would include the ABS. An adequate flush can't be achieved of the ABS without one.

 

I bet your cap is weeping and the resi is fine.

 

v8srfun above may be right, check the cap first.

I have change master cylinders on several vehicles without even having to bleed the system after the change.

You do need to bench bleed the new master cylinder with fittings and hoses connecting the brake line ports on the MC to the MC reservoir. Once that is done, remove the old MC taking care to not shake the brake lines after disconnecting them- surface tension in the fluid in those lines will keep them full of fluid to the end. Or have caps and cap them.

Leave plenty of fluid in, and the bench bleed lines on the new MC until it is bolted in and then, one at a time, remove the bench bleed line from each port on the MC and cap from the respective brake line and connect them.

The trick is to allow a little brake fluid to drip from the open brake port on the MC as you connect the brake line. With finesse, you won't even have to bleed the system, but probably should anyway.

Of course keep shop rags under the MC area and keep brake fluid away from painted surfaces. Brake fluid will remove paint.

 

I kind of agree. Wipe off brake fluid and see if it reappears.

I have seen this on my car when changing out brake pads. If the MC is full and you push caliper piston back it raises fluid level in MC.

Your brake fluid looks like it really needs to be changed.

 

Valid points on everything. First I'll try to change the cap. If that stops my leak I will consider a bleed. But I have to say that when I read posts on the brake fluid looking dirty I agreed fully. It does not look as dark as in the pictures. The pictures look nasty. Regardless I will price out a bleed of the system. Trouble is I do not trust stealerships at all. I could see them telling me some BS like I need a new ABS pump or something. I also appreciate the how to on bench bleeding a master. I have done plenty of masters in my day, just none on an ABS car. Again thanks for all advice.

 

Flushing the brakes is pretty easy if you are able to raise the car and put it on jack stands.

I have found the easiest is to put speed bleeders on all four calipers. Here is a link for the front speed bleeders for a 2001 C5 from Summit Racing:

https://www.summitracing.com/parts/r...position/front

Get a syringe from the auto parts store to suck as much old fluid as you can out of the MC, then refill with new fluid. Also some 1/4" fluid rated hose to connect from the speed bleeder on the caliper to a container on the floor. I use clear PVC Vinyl tubing so I can see the fluid coming out of the caliper.

In order, loosen one speed bleeder and connect the hose, then pump the brake pedal 5-6 times and then check the MC. I seem to remember that you can go 10 pumps before refilling but go fewer until you know the right number. It is important to not let the MC get low and pump air into the system. You can keep an eye on the hose to see when the fluid gets clear. Then on to the nest caliper. Don't forget to tighten the speed bleeder just bled.

A total of a quart or a liter of new fluid should do it.

The above method does not get the old fluid out of the antiskid/ active handling components, but that fluid will circulate out with a few stops hard enough to activate the system. You will know that has happened when the new clean fluid in the MC reservoir looks a little darker or hazy from being mixed with the fluid which came out of the active handling components.

A good shop will flush the active handling components using a Scantool or similar when flushing brakes. You probably have to confirm that they can/ will do that.

 

Thanks to all again.