Before I get any crap for it I have tried searching actually for the past few days and have yet to find my issue lol

Okay here's my story, I recently bought an 1998 Dodge ram 4x4 with an 8ft bed and the guy I bought it off told me it needed an ABS Unit. I was able to get a used one for it and put it in. Now here is where is gets kinda wierd, The PO when and changed everything master, booster, lines, calipers wheel cylinders basically everything but the abs unit. So after I put the unit in I started to bleed the brakes I get fluid to all 4 wheels and it was bled in the correct order about 5-6 times. I am now able to get some pressure while the truck is off it's not rock hard but there is some pressure. Yet as soon as start it I get nothing, it goes right to the floor. if i pump it while running the fluid level goes down at the master but once i stop i see bubbling at the rear of the reservoir and the fluid comes back. There are no leaks that I am sure of but I cannot seem to figure this out.

Any suggestions would be appreciated

Thanks

 

You used the word "crap" in your first post? Oooooh, bad.

Sounds like you still have some place that is sucking air. You may have to re-do some of the PO's work. I would start with the seals beneath the fluid reservoir that go into the master.

 

Sound like you have a master cylinder issue rather then a ABS issue. The abs will set the brake and abs lights off if there is an issue with it.

 

There is also a bleed procedure for the abs unit itself. I am guessing you have 4WAL? Grab the service manual from here for your truck, and have a read thru the replacement procedure. Some require that you have a scan tool that will talk to the abs.....

 

Okay I was kinda leaning towards master cylinder problem and I've heard horror stories of people getting two or three bad ones. It could be sucking air in but I would assume that at some point it would be pushing fluid out which it hasn't yet. I will try out the abs bleeding procedure when I get home today.

Also I forgot to mention that the ABS and Brake light were on before i replaced the ABS unit but since then have gone off. Granted that could just be temporary seeing as i disconnected the battery.

Thanks guys for your help!

 

Hey everyone!

So a lot has happened with my brake problem over the past week and I've been able to narrow it down to just he front brakes which is a relief because I really though the abs was screw up. There was a problem with the rear brakes in the fact that the previous owner assembled the rear drums backwards and the the springs completely wrong. but anyways I blocked off the front brake line from the master and have great pressure so my problem is in the front. looking at it I noticed no issues and I have followed the lines and hoses right the the calipers which are new and do not see any leaks. The drivers side hose is new as well and so are the lines so I really don't see where is it coming from any ideas??

 

Go thru all the lines and make sure all the connections are tight.

Usually, if you have someplace that can suck air in, it will most certainly blow fluid OUT when there is pressure on the pedal...... Any fluid leaking out the back of the master cylinder, and running down the vacuum booster? Have you pulled the vacuum line off the booster, and check for brake fluid in there??

 

I just put another new master cylinder in this weekend to cross that out and I didn't notice any fluid around it and I bench bled it before I put it on. I have taken the hose off once before but never noticed anything I'll have to check again and I'll have to go through the lines again.

I've read posts of people having problems with the brake hoses could the passenger side be giving me issues? Like i said the drivers side is new so I doubt it would be that

 

Usually line problems will result in brakes that won't release. You *should* eventually get a firm pedal, even if the line is internally collapsed.

Might try bleeding the fronts again, with a partner. have partner pump up the brakes, and hold pressure on the pedal, while you crack open the bleeder valve. This can 'shock' loose any air stuck in the system...... Give it a shot. See what happens.

 

The master cylinder was probably not bench bled before it was installed. It can be nearly impossible to get that air pocket out if you don't do this before you hook it up to the circuit and start attempting to bleed the rest of the brakes.

To bench bleed one, you disconnect both lines from it, fill the reservoir with fluid, then install some temporary lines that feed back into the reservoir and are submerged in the fluid in the reservoir. You pump the master cylinder until no more air bubbles are being discharged into the reservoir via the temporary lines. Once you achieve that, you can remove the temp lines (be quick) and hook up the main brake lines. Now you can bleed the rest of the system.