Chevy g30 1990 with abs
#1
Starting Member
Thread Starter
Join Date: Mar 2021
Posts: 2

I am having abs issues. My front calipers are staying ingaged and i can barley push in pedal.
any ideas as it has all new master cylinder, hydro booster, calipers, and even put a used proportioning valve in.
Can use help please
any ideas as it has all new master cylinder, hydro booster, calipers, and even put a used proportioning valve in.
Can use help please
#2
Super Member
Join Date: Jul 2013
Location: Northern California, USA
Posts: 1,620

I would guess it's one of two things:
1) The rubber hoses are collapsed internally and working as a sort of "check valve" to hold pressure in the front brakes.
2) The pushrod from the booster is slightly too long, preventing the master cylinder piston from retracting fully and allowing brake fluid to return to the reservoir. This can also be a result of the brake pedal not coming all the way up for some reason.
1) The rubber hoses are collapsed internally and working as a sort of "check valve" to hold pressure in the front brakes.
2) The pushrod from the booster is slightly too long, preventing the master cylinder piston from retracting fully and allowing brake fluid to return to the reservoir. This can also be a result of the brake pedal not coming all the way up for some reason.
#3
Starting Member
Thread Starter
Join Date: Mar 2021
Posts: 2

I would guess it's one of two things:
1) The rubber hoses are collapsed internally and working as a sort of "check valve" to hold pressure in the front brakes.
2) The pushrod from the booster is slightly too long, preventing the master cylinder piston from retracting fully and allowing brake fluid to return to the reservoir. This can also be a result of the brake pedal not coming all the way up for some reason.
1) The rubber hoses are collapsed internally and working as a sort of "check valve" to hold pressure in the front brakes.
2) The pushrod from the booster is slightly too long, preventing the master cylinder piston from retracting fully and allowing brake fluid to return to the reservoir. This can also be a result of the brake pedal not coming all the way up for some reason.
#4
Super Member
Join Date: Jul 2013
Location: Northern California, USA
Posts: 1,620

The pushrod might be adjustable. It's been a while since I worked on one of those, so I don't remember. You'll have to pull the master cylinder off and see if the rod from the booster is threaded.
To test my theory, next time you have a pressure buildup in the brakes, loosen the bolts holding the master cylinder to the booster so you can separate them about 1/8" and see if the pressure releases.
To test my theory, next time you have a pressure buildup in the brakes, loosen the bolts holding the master cylinder to the booster so you can separate them about 1/8" and see if the pressure releases.
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