Brakes

[akarpf]

I was driving My 84 c-10 swb 2wd with a 6.2 liter up and down the road I live on. and the brakes or hard some time and then they go slow the next time they go to the floor. I do not see a leak and the brake fuild is full. Can you HELP me out Please.


P.S. what is the thing behidden the master cylinder I do not know what it is and why the hoses goes to the power steering pump? Is it a brake booster like a gas motor would have.

thnak you

[NH2112]

That sounds like either a bad master cylinder or a lot of air in the lines. If the pedal feels good when you stop, does it slowly start to drop to the floor if you're on the brakes for any length of time?

The thing behind the master cylinder is the hydroboost, it is the brake booster and it is used on quite a few gas engines as well. It uses the power steering pump to provide power assist for the brakes. The small cylinder (probably gold colored) on the engine side is an accumulator, which stores pressure so you have power for a couple brake applications with the engine off.

[Robyn]

The issue you describe sounds like a failing master cylinder.

One of the inner seals (Piston cups) is leaking past internally causing the soft pedal.

You are going to need to replace the master cylinder.

Follow the included instructions for "Pre Bleeding" the new cylinder and then install it.

You can in many cases install the lines to the cylinder,and then with the lines left a little loose have a helper press the pedal lightly until fluid comes out around the tube nuts on the cylinder.
Once the pedal has been depressed and fluid comes out, have the helper hold the pedal and then tighten the tube nuts. Then have the helper release the pedal.

Have the helper pump the pedal up HARD and then one at a time slightly loosen the tube nuts just until fluid comes out, then retighten. (Do both lines)

This will get rid of the small air bubble in the end of the line and save you from having to bleed the whole system. (Sometimes though a complete bleed is needed to get it air free)

The unit behind the master cylinder is the "HydroBooster"

The diesel does not have any of its own vacuum to power a vacuum brake booster so the forces needed are derived from the power steering pump.

The hydrobooster is a hydraulic device that magnifies your foot pressure.

All the diesels use these as well as some of the HD trucks such as the 1 ton rigs with gassers.

Keep us posted


Robyn

[akarpf]

Hey , When I got the truck the brake where ok. I've been working on a problem with the glow plugs and I have been driving it alittle. a was driving it a week ago and I hit the bits and nothing happen and then the rear tires locked up and it got sideway. and I then drive 25ft and hit the brakes again and again and it did good and i what down the road and hit the brakes and it was soft again and then it locked up again. and then last night I drove it and it was doing it again . when I push the brake in and hold it the power steering we start squealing. and i do not see a leak on the lines that i can see.

[Edahall]

I had the same exact situation on my 82 Suburban but continued to drive it since I was on a long road trip. However, a couple of days later, the brakes completely failed while coming to an intersection and I had to jam on the emergency brakes. Turns out, the master cylinder was bad. It took me 2 days to order the master cylinder and about 1/2 hour to replace it.