My Spungy brake pedal

[jelag]

I think that if you look under your hood you'll find that your 05 has a hydraulic booster powered from the power steering pump and no longer has the vacuum assisted brakes.

I currently own an 05 3500 dually and can share with you that the brakes are no different than the 04, and 08 that I owned and have since sold. All 3 of the trucks have great brakes.

One of the brake fluids that's available is a silicon based fluid instead of common brake fluid. . the two are not to be mixed together... .

DOT 4, like DOT 3 and DOT 5. 1, is a polyethylene glycol-based fluid (contrasted with DOT 5 which is silicone-based). Fluids such as DOT 4 are hygroscopic and will absorb water from the atmosphere. This degrades the fluid's performance, and if allowed to accumulate over a period of time, can drastically reduce its boiling point. In a passenger car this is usually not much of an issue as the brakes are generally not used so hard, but can be of serious concerns in racecars or motorcycles due to their much more aggressive braking.

As of 2006, most cars produced in the U. S. use DOT 4 brake fluid.

A different compound of friction, something way off from the stock coefficient of friction could easily create a very hard pedal, and it would require a much higher pressure to stop the truck. The higher the coefficient of friction the higher the pressure to make the brakes function... . Could the brake pads be so hard that your power brake system can't generate the pressure, thus the very hard pedal...

Some racing formulas require a much higher pressure that our trucks were not designed to generate which would show as a hard pedal...

Hope this is some help and gives you some other thoughts... .

 

[JeffBob]

Jim, thanks for your perspective. I put a Valvoline high temp DOT 4 fluid in the system last year, the Hawks are the super duty truck pad. I try to flush the fluid every two years on my street vehicles but definately just before each event for my track car. Esp inthis humidity in Atlanta!

So unless there's some massive air bubble that was ejected from the ABS, which didn't engage when this ocurred, I'm inclined to suspect a problem in the brake boost system. Thanks for correcting me that it's not vacuum, but hydraulic boost.

To your point, i found another post where this symptom - the soft pedal - preceded a complete power steering pump failure by 2000 miles, suddenly leaving the driver with no power brakes or steering!

With the weight of these trucks, that's got to be impossible to handle.

At his suggestion, will check power steering pump for metal - wil sample it and send it to a lab.

I don't see a power steering pump part for my 2005 3500 on the Genos's site though.

 

[JeffBob]

In reading through my Haynes manual this am where they outline a test of the power booster, i'm now convinced that's the problem. Had planned to flush the power steering systems on the Dodge and on my BMW. Dodge now gets priority. we'll see if my mechanic confirms the diagnosis.

Why do i feel like i need to replace most all accessories every 60k on my Dodge and my BMW?

Since i need to flush the cooling system (it's a year overdue) I'm tossing the hoses, water pump, thermostadt, pulleys, tensioner, belt and other suspects include harmonic balancer, power steering pump and brake power booster ...

I'd rather swap it a little ( a lot?) prematurely in my driveway then end up stranded on an interstate.

Got a flat on my last trip and lost half a day sourcing a simple trailer tire, so now going to carry two trailer spares ...

 

[RBellah]

Lots of truth in these posts about the moisture in the fluid. My fluid looks brown and I just purchased a electronic brake fluid tester from Geno's and it showed my fluid to be at a high level of moisture and needs to be replaced. Just for grins I used the tester in a cap full of new fluid to see if it knew the difference and it was in the prefect tolerance mode. I am going to change mine soon and also need to purchase a fluid bleeder tool. Not sure which fluid I am going with yet, but I may check to see what Amsoil sells and recommends for my 2006.

 

[jelag]

Jeffbob

I keep my trucks for 500K miles and I don't replace stuff unless it fails. . there are 2-3 brands of power steering flushes where you pour in the flush, run the system for 15 min and pull the return line and than pour in 3-4 quarts of ATF... and than re-install the return hose and put in fresh power steering fluid... One of my best friends owns a Transmission shop and I just follow his guide lines... Between the Fords and the Dodges, it must be 10 trucks in the past 20 years or so. . I've never replaced a power brake booster, either vacuum or hydraulic or a power steering pump... Did a lot of vacuum pumps on the Fords... .

Most of your list... """Since i need to flush the cooling system (it's a year overdue) I'm tossing the hoses, water pump, thermostadt, pulleys, tensioner, belt and other suspects include harmonic balancer, power steering pump and brake power booster ... """

I rarely touched on most of those trucks during their life... maybe one belt and tensioner, a water pump on the Fords, never on any of the Dodges, 1 cooling system flush and that's about in the life of the truck while I owned it... and I can't remember ever having a failure... were we had issues was u-joints, transfer cases from lack of oil,air condition compressors on the Fords, and a couple of heater cores...