Hello,
My brake light is on, on the dash of my 72 cutlass. I figured out the distribution block is the culprit.
I'm also not getting any brake fluid to both rear drums.
Is this a distribution block problem or could other things be
wrong?

 

Are there any leaks to the rear of the block?

 

Almost definitely the master cylinder.

- Eric

 

No. There are none. I placed cardboard under the engine and nothing all week. Not even a drop.

 

Do you really think so? Could it also be the brake lines?
Or like I mentioned earlier the distribution block is triggering the light on the dash.
I read that when that happens the system loses pressure to one side. Could the master cylinder cause this?

 

Bad master cylinder --> low / no pressure to rear --> light goes on.

How's your brake fluid level? Losing any in the rear section? Does it get higher in the front even though you didn't add any? Any wetness at the bottom of your brake booster?

- Eric

 

Ok. Makes sense to me now. My brake fluid level is fine now. When I first opened the top the back was almost empty. I was trying to bleed the rear and nothing would come out.
There's no wetness on the booster and it's leaking nowhere that I can see.
I filled it up last weekend. I'll go check it out tomorrow and check the level.

 

A bad seal can allow the fluid to pump from one bowl to the other, or from one bowl out the back and into the booster (or the firewall insulation if non-power) without ever getting to the wheels.

M/C is a cheap and easy fix.

- Eric

 

I have ran into this before. On two cars it turned out to be two different/unusual problems.
The first wierd one turned out to be the rubber line at the rear of the car had collapsed inside.
The second wierd thing turned out to be a residual valve failure. The valve was located about half way back, sort of under the rear of the driver seat. I removed it and all was fine, replaced it with a brass fitting.
In both cases I found the problem by having someone hold the brake pedal down as if I were bleeding the brakes, and cracking the lines at the fittings to allow a fluid leak. This method will work for you. Have someone hold the pedal down and start opening the fittings. First at the line going to the distribution block, and going from there to the next, where the line leaves the block and heads to the rear. Follow the line to the rear, look for a residual valve, keep opening the lines/fittings one at a time. You will find the bad part when you find where the fluid stops flowing.

 

I agree that those two problems are possible, and I agree with your diagnosis technique, but I've still got my money on the master, both because of the low rear bowl, and because it's just more common.

Dice - don't fail me now!

- Eric

 

I had the same issue on my 72 and it was the master. I could bleed and bleed all day and never had anything for pressure in the back. I'd have a friend pump the pedal 10+ times and all I got was a slight trickle out of the bleeder. new master and I was good as gold.