Got a 94 montero sr with no to little to no brakes. I just bought it, the previous owner just said that they stopped working. The abs light had been on for a while. I filled with brake fluid and did get very small amount of braking. I have been all under the vehicle and found no leaks. No leaks around the master cylinder. I did notice what looks to be like a leak from the bottom of the abs modular (on the passenger side front fender well). Can they be rebuilt, common gasket leak? something loose? replace? Throw away no more abs? Any suggestions? Thanks

I filled with brake fluid and pumped the brakes for a good bit. I did actually start to feel a little pedal. I got under vehicle and inspected all lines found nothing. It sat for several days in the same place, I went back and inspected again, nothing. Nothing along frame or dripped on floor. Only thing I found was that the fender well was wet under the abs mod. I'm going to try and loosen it with out disconnecting the brake lines so I can see under it. I,m sure it needs to be bleed but it has to be leaking somewhere. Are the abs mod a probable issue or do they never break?

Never dealt with ABS, I'm more of a Gen 1 guy. But you are talking a 20+ years old vehicle that sat for a bit. Good chance there is an issue with it.

I took the the abs mod loose. It weeping out the bottom. But I'm not convince that I don't have a booster issue. With the vehicle off I can pump the brakes with no pressure build up.

More likely you have bad seals in the master cylinder, fluid is being pushed past the piston in the clyinder. ABS will not likely cause no peddle. Bad Booster will cause hard peddle. Some might say not to do the following but if you need to isolate the master cylinder to see if it is an internal leak. Crimp off the calipers at the rubber brake lines with hose crimps or vise grips with rubber tubes on them to protect the hose (if the hoses are old it may damage them so use discretion) don't have to crimp the hell out of it. Then if the peddle still sinks to the floor with light pressure assuming the system has fluid in it you have bad seals in the master. Abs has valves that move when the wheels slip basically the same as pumping the brakes, it allows fluid to pass freely if it's not actuated this is why you have base brakes with a bad ABS module. If the peddle is hard with the crimps in place you have a leak elsewhere your not finding. Or just rebuild the master for good measure and cross your fingers;) peddle sink with no leaks more times then not the master.

I had no brakes as well. Replaced both the booster and Master Cylinder since they were both 21 years old. I figured I would just take care of all of it since I was in there anyway.

have you checked to see if the calipers are engaging. Had a fiero that sat for a long time and the caliper pistons seized. Bad thing about brake fluid that sits, it absorbs water. Water corrodes the insides of the fieros calipers.

You say you filled with brake fluid, but did you do a true flush???? How did the fluid bleed thru the lines? Even all around?

Also how do the lines feel? I have heard of the rubber lines collaspsing degrading with time. again a GM thing. Why we swapped over to stainless braided lines.

I would start with bleeding the lines. Once you get the air out ( assuming the master cylinder works well enough to allow you to), any leaks should be easier to find.

Missing fluid is often from the back of the master cylinder. Anything else should be easy to spot.