2003 Ram 3500 brake issues!!

[BuilderML]

I know this is not a truck forum but this is the only forum i belong to so i figured i would ask to see if anyone on here has an idea as to what might be wrong.
Spec: 2003 Ram 3500 P/U 5.9 diesel.
I have a problem with the brake pedal going down or being soft after a hard turn at low speed after truck is started. I'll give you an example:
1)I start the truck apply brake to shift from park to back out of parking space / garage.
2)No problems at this point brake pedal is firm as it should be.
3)I turn the steering wheel to head out of garage/ parking space. This would be a few turns of the steering wheel kind of like pulling a K turn.
4)Now this is where the problem starts.
5) The next time i apply the brakes to try to stop or slow down the brake pedal drops to the floor with very little back pressure. Almost like if i blew a brake line.
6) Now i pump the brakes a few times and everything is back to normal.
7) No problems driving or stopping until i go thru the same steps of several steering wheel turns as listed above.
Now i understand the the hydro boost unit is what provides the power brakes which is being feed by the power steering unit.
I am not a mechanic but i am able to turn a wrench and figure stuff out.
So before i go replace the power steering pump and hydro boost unit i would like to see if you guys might have some ideas for me. I would hate to change a part just for the heck of it while crossing my fingers praying for it to be the problem.
I do not have any issues with the steering on the truck, works as it should.
I hope i have provided enough details for you guys to give me a hand, maybe someone has had the same issue or knows of an issue like i am having.
Thank you for your help.

I'll also add that i did just blow a brake line in the rear about a week or so ago and have replaced all the rear brake lines including the one the runs the length of the truck along the frame rail. I did bleed the air out and no leaks that i can see.
I don't think that this is part of the issue but i figured i would add it just in case.

 

[kencunningham]

Check the power steering fluid to see if it is foaming, if it is then you are sucking air.

 

[orezok]

I would check the calipers to see if they are free. It's possible they are sticking and the couple of turns is pushing the piston back. The next application requires a stroke to push the pad back against the disc.

 

[antlers125]

Might need to do an automated ABS bleed. This requires a diagnostic scanner.

 

[Wayne64SS]

First thing I would check is the brake hoses and calipers in the front of the vehicle to make sure nothing is coming in to contact or leaking or sticking. Other than that it sounds like the hydroboost. Definitely not the PS pump.

 

[kw22614]

Check the high pressure hose from the steering pump. You look under the truck while someone is inside with the wheels turned hard both ways (truck running) - sometimes the rubber hose will seep when old and you can't see it untill the pump is at full pressure. Also I'd rebleed the entire system - start at the farthest wheel, RR then LR then RF lastly LF. Hope you get it. let us know how it turns out. KW

 

[Wayne64SS]

Check the high pressure hose from the steering pump. You look under the truck while someone is inside with the wheels turned hard both ways (truck running) - sometimes the rubber hose will seep when old and you can't see it untill the pump is at full pressure. Also I'd rebleed the entire system - start at the farthest wheel, RR then LR then RF lastly LF. Hope you get it. let us know how it turns out. KW

if it was a PS pressure issue the pedal would be going hard on him and or steering becoming difficult.

 

[Raised on a Deere]

I would be more suspicious of the master cylinder. The only way the pedal can go to the floor with no feel is for air to be in the lines, fluid leaking out somewhere (will observe falling fluid level if this is happening) and baring those the master cylinder is leaking down some how. They can be a bit intermittent on that master cylinder leak down sometimes with just the right wear situation or ruptured seal. I have seen them hold on one push and not hold on the next. Could just be all mixed in with you turning and only time will tell. I would not feel secure driving down the road knowing this is going on. A bad brake line could be flexing cause a leak in the turn but then the fluid level would drop. Leaking master will probably get worse pretty soon.

Otherwise you have a goblin I don't know about.

I have a 2003 and am in the midst of replacing the master cylinder.

 

[kw22614]

If the HP hose has a small seepage problem it will also allow a small amount of air back in when pressure is released, causing a temp 'soft pedal'.
Had almost this same prob on an old Ford F150 and took me a couple weeks to find the prob - replacement of the HP hose and complete system bleed was the fix.

 

[BuilderML]

So i went out today and sprayed the P.S. pressure lines with brake clean at the fittings and blew them off with the air hose so they would be nice and dry.
With the truck running at idle i had someone inside the cab turning the wheel from right to left and back a few times while looking over all the fittings.
I did not notice any fluid at the fittings everything looks nice and dry atleast now over the next few days i'll see if the fittings get wet. I'll start with the easy stuff first and keep working my way up. Thank you for the replies guys. Again anymore ideas you quys can come up with would really help.
Next step pull the front wheels and confirm the front calipers are not sticking. I'll keep you posted with updates and what i have done so atleast if this happens to someone else it may also help them out. I hate going to the garage for repairs. I figure i can replace alot of parts doing the labor myself versus having one problem fixed at the garage.

 

[Soundguy]

are rear brakes drums on theose? if so for sure check for leaks at the cyls.

 

[sd455dan]

Only the e brake ones - rear main brakes are discs at least on my 03 srw

 

[Egon]

Not sure what to call it but maybe look at the vacum boost arrangement. There was a recall on earlier year models. ??

 

[kw22614]

Builder, don't just look at the fittings - it's the hose itself that will seep. While having someone turn the wheel back and forth run your hand over the hose to feel for a damp spot. Hope this helps - good luck.

 

[BuilderML]

I have some more info to add. So today messing around with the truck i would go from forward to reverse back to forward. After going in reverse and applying the brakes a few times and when i went back into forward the first time i applied the brakes the pedal was soft. Only for the one time was it soft after that it was fine. I did this a few times and each time going from reverse to forward the first time applying the brakes in forward it was soft. I did not turn the steering wheel this was all in a line no turns. Has me thinking about maybe a bad/slow caliper. What do you guys think?

 

[BuilderML]

are rear brakes drums on theose? if so for sure check for leaks at the cyls.

E -Brake is drum,, rears are rotors.

 

[BuilderML]

I would check the calipers to see if they are free. It's possible they are sticking and the couple of turns is pushing the piston back. The next application requires a stroke to push the pad back against the disc.

After todays test i am thinking the same thing. I'll take wheels of in the morning and check it out.

 

[Soundguy]

let us know how it turns out please.

good luck, be safe.

 

[sd455dan]

After todays test i am thinking the same thing. I'll take wheels of in the morning and check it out.

If turning the steering wheel is causing enough rotor run out to push the caliper piston in enough to lose a major amount of brake pedal travel, (even if the piston is sticking) the unit bearing is probably shot.

Even massively warped rotors will not cause this much pedal loss. JMO

i would jack up the front axle and grab the tire BEFORE removal to see if there is excessive unit bearing play.

I can't imagine this is the cause. then again , been wrong before...

Have you checked out Cummins Forum- and done a search. I have yet to see intermittent loss of brake pedal (with no external fluid leak) that was not master cylinder related - unless possibly the ABS has some air trapped in its system...

Good Luck and

I also would like to know the root cause , since my truck is an 03

 

[BuilderML]

If turning the steering wheel is causing enough rotor run out to push the caliper piston in enough to lose a major amount of brake pedal travel, (even if the piston is sticking) the unit bearing is probably shot.

Even massively warped rotors will not cause this much pedal loss. JMO

i would jack up the front axle and grab the tire BEFORE removal to see if there is excessive unit bearing play.

I can't imagine this is the cause. then again , been wrong before...

Have you checked out Cummins Forum- and done a search. I have yet to see intermittent loss of brake pedal (with no external fluid leak) that was not master cylinder related - unless possibly the ABS has some air trapped in its system...

Good Luck and

I also would like to know the root cause , since my truck is an 03

I'll be checking for any play today as well. The only thing is i was NOT turning the steering wheel it was just going from forward to reverse and back into forward in a line. I will be sure to post results once i get this figured out. Again thanks for the help guys.