Brakes out- booster? - no pedal when running (1 Viewer)

[jbsax]

I have been fighting 80 brakes for a couple weeks now. I have searched and read many threads, but can't draw any conclusions from the ones I have read. Problem started with suspected air in the lines (and there was). Bled that and everything was fine for a few hundred miles. Pedal was a little spongy again, so I decided to bleed again. Finally got a hard pedal with the engine off. Cranked it up, and pedal goes to the floor with minimal foot pressure.

Originally bled via the the 2-person, pump and bleed method. Then became aware of the problem with potentially ruining the master cylinder. I ordered a new OEM master cylinder. After installation and bleeding with a vacuum pump, I got a hard pedal. I have now bled almost 3 quarts of fluid through the system. The fluid is almost as clear as it comes out of the bottle. Cranked it up, and the new master cylinder has the same problem.

I understand that the brake booster multiplies and can compress any air, but this pedal feels as hard or harder than other vehicles I have bled the brakes in, that worked fine afterwards.

I feel like the brake booster could be the problem. So, is it possible for the booster to go bad, but create much more assist than it should?

I bled the system, RR, LR, RF, LF, LSPV.

Any help will be appreciated. I am getting very frustrated with this beast, but don't want to throw money at more parts that may or may not fix the problem. I want her back on the road and more importantly the trail.

Thanks in advance for the advice!

 

[gotmud]

I doubt the booster is your main issue here. 80's can be a pain to get bled properly. You may want to bleed the master cylinder and then bleed the system again. HTH.

 

[jbsax]

This is the route I am going to take. Brakes were operable. I got it in my head that they were spongy, so I bled them. I obviously did something wrong and introduced air to the system. They did not work after that. I am going to order a power bleeder and go that route. That should remove some error from me. I tried the brakes again yesterday and if the pedal is pumped quickly, it will build a little pressure. My guess is air. Thanks and I will post the results.

 

[OGBeno]

As Land Tank has said many times, and I agree, the LSPV, usually the culprit.

I've gone through 2-3 quarts of brake fluid before to get the system clean and airless.

Good luck.

 

[Michael Hanson]

I know there are many ways to bled the brakes but I have never had any problems with the old fashioned 2 person method. I just did a toy booster in our 1991. 2cents Mike