MARF75

Before trying to bleed my 4th MC I thoroughly read the instructions.

It mentions a rubber cover over a pin on the proportioning valve on some vehicles, my truck happens to have this pin. You are supposed hold the pin open while bleeding using an OTC tool #7853 ($30) to get the air out of it.

Does anyone know anything about this or have any input?

thrashingcows

I have bleed dozen of systems, and many of them have had this pin. Not once have I ever messed with it. Most of the time when I bled my brakes I do it by myself with my state of the art brake bleed system....



I usually don't bench bleed my MC either....just lots of fluid and time to let things gravity bleed. When you leave things open to gravity bleed the air will move up the system and into the MC. Been working like this for years with no problems.

MARF75

Any certain specs on that bottle? Does the cap fit tight around the hose? Can you just crack the bleeder then pump away on the pedal?

I bench bled my MC until there were no air bubbles. Now I have it hooked up to the truck and am letting it gravity bleed 1 wheel at a time starting with the right rear. I put a piece of clear vinyl hose on the bleeder that drains into a jar. I made the said hose go up higher then the wheel cylinder/caliper then down to the jar.

NJTman

Yes.

There is a clip that is sold (tool #C-2141) (see attachment) and it's ONLY TO BE USED UNDER PRESSURE BLEEDING and not vacuum or pedal pump bleeding. The clip keeps the valve open so that the pressure bleeding gizmo will be pressurized to the front calipers, otherwise the valve prevents it from flowing to them.

you can remove the rubber cap and hit the brake pedal. It moves in and out, based upon how much pressure you put on the pedal.

I used my Brand new mity vac the other day, and now my pedal is smushy again. I had previously pump bled them with a buddy, but I wanted to try out my new migty vac. It was counterproductive to what I wanted to accomplish.

thrashingcows

The bottle is just a regular water bottle form the store. I punched a hole in the cap and fed the scrap piece of vacuum hose down and into it. I also punched a small hole in the top of the bottle near the cap as a breather. I usually just crack the bleeder screw, then hook up the hose and let it sit on the ground. Then I pump the pedal about 6-10 times, then check the MC for fluid level, then pump a few more times. After the pumping I let it gravity bleed for 10-15 minutes then close it up and move on to the next wheel.

Like I said I've been doing it like this, by myslef, for many years now and have never had a problem.

MARF75

well, I made 1 of those handy dandy bottles and used the above guidelines.

After about 4 pumps of the pedal it got pretty hard. So I continue all the way around the truck and the pedal stayed pretty hard the whole time.

Then when i started the truck to go for a ride, the pedal slowly started to fade. I had very little brakes so I backed her back in the garage and here I am.

thrashingcows

Well it is more then likely the never ending problem you guys seem to have with the early ABS system these trucks run. Probably the RWAL? valve on the back axle or something?

This seems to be a common problem for the 1st Gen trucks. This is why I'm glad my 84 crew does not have any of that stuff. Just the basic brake system that always seem to work with no complaints...

DO some searching through the archives...there are a ton of threads on poor brake pedal feel, or braking.

MARF75

all the RWAL stuff is deleted

thrashingcows

What about that junction block just below the master cylinder? Is that still hooked up? I personally do not know how this early ABS system works, just throwing out there some idea.

I know on my system all I have from the master cylinder to the wheels is the proportioning valve. If this is all you have too then maybe you do have a proportioning valve?

maybe368

Your experience was my experience, that is when I dumped the rear drums for discs. I still have the dump valve and my brakes are dreamy. The evidence is pointing to the drums, not the dump valve. As I have said in the past, I think it is a matter of luck whether or not the drums work or not. It was a crumby system, because in all my years of wrenching, this is the only vehicle that I have had to modify to get the brakes right. Admittedly, they worked for many thousands of miles. but, the problem is you cannot maintain them without risking failure and that is not good...Mark