Hey all,
I've got a '92 F350. I am having a squishy brake problem. I just replaced the power brake booster, vacuum pump, and master cylinder. I have bled them several times and they are still squishy. I don't think its a leak because I'm not loosing any fluid. Any ideas would be great.

Thanks.

 

Did you bleed them in order? The correct order is right rear, left rear, RABS module, right front, left front.

 

I did - R rear, L rear, R front, L front. I don't think I did the RABS module. Where is it located?

I did bleed something on the driver side of the truck, about a foot or two below the master cylinder. Is that were the RABS module is?

 

yes it is bolted to the inside of the left side frame rail about level with the drivers feet.
Some guys would bleed it first, some in the sequence I posted.

 

I have bled that a few times then already.

There is one hose I see that goes to the R front and it is a little wet. But when I pump the brakes I don't see or feel any fluid coming out, could that be sucking air into the system?
It doesn't seem like it is tho because when I bleed them, I don't get any air coming out.

 

If you think there is a leak at that hose then you should replace it anyway.
Can you describe a little better what your problem is? If you have a good high hard pedal with engine off but low pedal with engine running then you still have air in the system.
If you have a good pedal when braking but it sinks under sustained pedal pressure you might have a bad RABS module.
Did you bench bleed the new master cylinder before connecting it?

 

I basically have what you said, with the engine off I have to pump the pedal a few times and then it is nice and hard. But with the engine running it is very low and mushy, and does not stop all that great.
No, I did not bench bleed the master cylinder. Should I take it off and do it?

It doesn't seem to be air tho, because there was dirty fluid in the old master cylinder and when I put the new one on I bled it until clean fluid came through.
Could there still be air in the lines somewhere? How would I get it out?

 

X2 on replacing that brake hose. If something in your brake system is leaking fluid, replace it. I thought that was common sense.

If you didn't bench bleed the master cylinder, then there is air trapped in the front of the cylinder because of the angle at which it sits. You either have to remove it and bench bleed it or raise the back of the truck up enough for the air to be pushed into the lines.

It also sounds like your rear brakes might be out of adjustment.

 

Ok, I'll try bench bleeding it tomorrow hopefully. I'll let ya'll know if that fixes it.
Thanks for the help.

 

I had the identical problem with my '92 F-350. I replaced most everything and then had a mechanic do the same. After having this done I had the cleanest break fluid around and still a soft pedal. As a last resort the mechanic replaced the ABS module/valve and that fixed everything. This is the assembly that is inside the frame roughly under the driver's seat that has a number of break lines running to it.

I was pretty frustrated with the situation for a long time and it sure was a nice change when the work was done.

Good Luck.

 

Sorry, I didn't read all the posts that well. Lazy K is correct with the bad RABS module.

 

If I keep having problems I think I will get a new ABS module. But as of new I think it's fix.
What I did - I bench bled the M C and rebled the whole system. And then I noticed that the rear brakes needed adjustment, so I adjusted them and now it seems to be working good. We'll see when I drive it a little more if the problem cames back or not.

Thanks for the help.