Brake Bleeding Issue

[Downeaster1]

Hey all,
So last week I bought a 1986 325e (my first E30, but 18th BMW). It's a 5spd with 99,000 miles. It's been sitting since 1999, and the rear rotors are totally rusted out. I went to throw on new disks, pads and a sensor then went to bleed the system, but no fluid came out of the back. Fronts bled just fine. Removed the brake lines from the calipers to isolate the calipers as being an issue, and still no fluid came from the lines.

Possible related side note: The ABS light is on.

Any thoughts? I've searched the forums a bit and there is some talk of possibility a bad ABS unit would cause these symptoms. Just wanted to get some opinions first.

[roguetoaster]

Sure, it's possible that the ABS pump has failed, but either way you'd need to find the furthest forward point where the rear lines are flowing fluid.

[AndrewBird]

My guess is the master cylinder is bad. Crack a line there and pump the brakes. If little to no fluid comes out, there is your problem.

[Seawolf]

May be just corroded brake lines or a bad regulator.

Check the rear brake feed line (the one that comes out of the front of the abs unit by the left headlamp rear shield), if you have fluid there then that part of the system is likely okay.

There is a pressure regulator under the brake servo mounted on the left frame rail, these get corroded and blocked if you braking system has water in it (which is likely after this amount of time) and has rotted the hard lines from the inside out.

That regulator is a PITA to get out...

Other than that check the rear brake hardline from the regulator back to the rear T and the 2 hard lines from the T to the trailing arms.

As you work backwards open the brake line connections to see if you have fluid there.

Be careful when opening those junctions, a car sitting for that period of time will very likely have corroded hardlines.....and they will break if they can.

[Downeaster1]

Thanks for all the tips and pointers; I'll check everything out tonight.