2nd Gen Non-Engine/Transmission Hard brake pedal and no brakes

[kebees4]

I have noticed that occasional that when I go to stop the pedal gets hard and I have little or no brakes. This has happened 6 - 8 times in past month and almost caused an accident for me today. Can anyone give me suggestions what to look for. Power steering fluid is full. It is getting scary.

Thanks

 

[gwagner]

check your brake booster vacum line for cracks or holes. i forgot to reconnect mine once and it did the same thing. or you booster could be going out.

 

[Dave M]

Brake Booster

I have a leaking hydroboost unit in my 97 and, if yours is the same, then it doesn't use vacuum for boost but instead uses the power steering pump fliud to the hydroboost unit for boost (not vacuum). As I understand it, others can correct me if I'm wrong, starting in 97 the vacuum booster was replaced by the hydroboost unit. The hydroboost unit is bolted to the back of the brake master cylinder and then the hydroboost unit is bolted to the firewall on the other end in my 97. It provides brake assist by using the power steering pump fliud (through lines from the power steering pump)



I am getting a new (not rebuilt unit) from www.hydroboost.com for $275. There is a round looking soup can thing attached to the boost unit called an accumulator that supplies boost when the engine is off.



The accumulaor allows you to get 2-3 pumps on the brake pedal of boost pressure before it drains when engine is not running. So if your pedal is hard, the accumlator may be bad and the whole boost unit (I believe) has to be replaced.



My hyroboost unit is $525 new from Dodge or a rebuilt from NAPA for $230. The trouble with the new unit from hydroboost.com is you must send your old one in so they can transfer the brake pedal rod, the firewall mounting bracket, along with the master cylinder pushrod to the new unit.



So if you have a hydoboost unit on your 2001 then that could be your problem. Make sure your power steering fluid is full first and check for leaks. Mine leaked under the hyroboost unit (where it bolts to master cylinder) and then down onto the steering shaft.



Go to www.hyroboost.com for good pics and descrition of how this thing works. If yours really is vacuum boost than forget all this... someone else with a 2001 can chime and and prove me wrong.



Hope that helps. I'll be pulling mine out Friday and shipping it.



Good luck,



Dave

 

[kebees4]

It looks like I have a hydoboost unit. Is there any way to test it? I would hate to buy a new one if thats not the problem. How difficult are they to change? Will I need any special tools? A couple weeks ago the flid was a little low. Could there be air in the system?

 

[Dave M]

I haven't replaced mine yet but I did unbolt the master cylinder from it to check out the leak. The bolts were not easy to get at and the bolt heads were soft and easy to round off but I unbolted it without disconnecting the master cylinder brake lines. I haven't removed the unit from firewalll yet tho. Others have said it isn't too bad to remove. I'll let you know after this weekend when I do mine.



First determine where the leak is. You need to determine if the boost unit or master cylinder or power steering pump is leaking. I went to NAPA and put ultraviloet transmission dye into the power steering reservoir. The next day I hit it with a black light at night and it glowed verifing the boost unit was leaking where the boost bolts to master cylinder. It sounds to me like your boost unit is bad since your brakes are hard (no boost pressure).



This is from the hydoboost.com web site:

The bottle on the side of most hydraulic brake assist units is referred to as an accumulator or nitrogen reserve. This stores up hydraulic power steering pressure in the event of an engine stall condition, to provide reserve brake assist power for up to 3 applications of the brake, similar to how a vacuum booster would function in an engine stall condition. Upon the first application of the brakes after an engine stall, you would find approximately 60 - 75% of the normal assist available, then if you were to release and apply the brakes again, you would find approximately 30 - 40% assist, then again approximately 10 - 20%, until you have depleted all stored reserve assist. Once you have depleted all of the stored pressure, the brakes will no longer have power assist and will be manual in their operations. The minute you start the vehicle back up again, the accumulator gets filled back up with pressurized ps fluid again and is ready to go!

Here's more:

Yes - it is actually recommended that the brakes be bled with the engine off, which simply provides a "manual mode" of operations - no harm is done to the brake booster using this method. The components inside the brake booster simply "stack up internally" to provide a full manual brake actuation. You will find that the brake pedal height will be about 2 inches lower when the engine isn't running, or without the lines connected, as compared to a "powered up" pedal height. If brake bleeding is performed before the booster pressure lines are connected, some minor power steering fluid discharge may occur from the ports, which is completely normal. Since the hydraulic brake assist units provide a full manual mode of brake operations when powered down, the lack of a firm brake pedal during brake bleeding procedures clearly indicates that air is still trapped in the lines, and / or possibly an indicator of ailing brake components elsewhere in the vehicles braking system requiring service. If the vehicle is equipped with rear drum brakes, or integral emergency brake type calipers, please insure that these components are in a proper state of adjustment, as this will greatly impact brake pedal height and operations in service.

Hey... If you can find a leak it would help narrow down the trouble.



I have heard air can get in the lines but the boost unit usually can purge it. Are there bubbles or foam in the power steering fliud. Jack the front end up and turn the wheel left and right a few times and check for bubbles (air) in the fluid. Look for a leak. Maybe the low fliud level caused air to get into the system. I have heard going lock to lock will purge the air.



Hope that helps some. Others who have done this will jump in and help I'm sure. Sorry for the long post



Dave

 

[kebees4]

Thanks for the help I will get some dye and try that first. I don't see any bubbles in the power steering fluid, but there was when it was low. That is a costly part to only get 57,000 miles of service.

 

[Dave M]

Here's a thread that someone with a 2001 had hard brakes and it was the vacuum pump:



http://www.tdr1.com/forums/showthread.php?t=120225&highlight=hydroboost



Here's an excerpt from that thread:

Fluid levels are fine with no apparent loss of fluid so hopefully the the nitrogen canister is still functioning. Brakes are extremely hard to press so obviously the Power Steering pumps assist to the brakes hydroboost are not functioning properly.

I removed the pump first (its easy but I can see that it will be difficult to put back on because of the coupler!) and found that the problem is not the fingers on the pump that engage the coupler and the fingers on the Vacuum pump were found to be sheared off. After removing the vacuum pump (easy by the way!) I found a coupler the looks like a 1/4 inch washer with 4 notches, that was intact and the fingers that are on the vacuum pump were sheared off.

So it could be vacuum pump, power steering pump or booster. Do you see any leaks anywhere? By the way, when my problem started the p. s. fliud was low and the symptom was hard brakes, screaching p. s. pump when turning steering lock to lock. I found the hydroboost leaking... hopefully that is the only problem.



Also, after I put in the 1 ounce of UV dye (it was a greenish yellow color) I could tell the difference in the color of the fliud leak even before hitting it with the UV light. It was tinted a orangish brown like color... a noticable difference to me.



Good luck



Dave

 

[kebees4]

I thought if you had hydraboost you didn't have a vacuum pump. Is this correct or do you have both.

 

[Dave M]

I thought if you had hydraboost you didn't have a vacuum pump. Is this correct or do you have both.

You have both. The vacuum pump is still used for things like heater controls but the brake boost is now off the power steering pump which is attached and driven by the vacuum pump. Apparently hyroboost brakes are much more reliable (when they work) than vacuum boost which, depending on engine speed can have low vacuum and therefore low boost IMHO from the searching I've done.



If you think the boost unit is costly wait til you see the price of the vacuum pump ($1500 new), but reseal kits and parts are available, but it is a real PITA to get out compared to the boost unit IMHO from what I found in searchs



Dave

 

[kebees4]

Not much longevity of the parts considering what they charge for the trucks. Shouldn't that be warranty work since is part of the Cummins.