Brake Booster noise
 

History: Disk/disk setup, Booster/master cylinder from CPP 4 yrs old (previous owner installed), new disk/disk prop valve. Rear disk conversion last year. Just installed new hardlines front to rear, new front rubber lines, new calipers and rotors.

Brakes still seem mushy, one pump seems to help but multiple pumps have no effect. Not much better than before the rear conversion. Can't stop the vehicle fast and barely can lock it up.

I have replaced all fluid and bled bled bled, pumped out all old fluid prior to hard line replacement last month.

Today I checked the check valve and it fell apart...brittle. Hoping that was the problem...nope.

So i replaced the grommet, check valve and 3/8 line. No change except it now makes a popping noise when I turn the motor off.

Getting lots of vacuum from motor and also getting the rush of air when pulling off check valve from booster.

What am I missing? Think my master is bad?

Here's the video of the booster noise:
https://www.youtube.com/watch?v=_I5IRF_LzhY

Picture is a few weeks old but shows my setup.

thanks

Re: Brake Booster noise
 

Check it for leaks by spraying it with soapy water, also the hoses in around the main vacuum line.

You might get a surprise, any bubbling any where and you have a leaker. If not but the sounds of that video, something is sticking.

Re: Brake Booster noise
 

There should be no bubbles near a vacuum leak.
I would try another check valve. That one may be bad. Even new parts can be bad.

Re: Brake Booster noise
 

I'll try both, those are both easy enough - thanks!

I think I also need to track down some new clear tubing to get a tighter fit. I'm using a hand pump and I kept seeing small bubbles which I kept blaming on the seal on the tube and bleeder.

Just incase it is the master cylinder what would be the part number for replacement for disk/disk?

Re: Brake Booster noise
 

Brakes are finally working awesome, no more needing to stop on them.
It ended up being the CPP booster. Went with a Tuff Stuff booster thru Summit.

Just wanted to follow-up in case anyone has the same problem in the future.

Re: Brake Booster noise
 

Always appreciate it when people come back with the solution instead of disappearing!

Re: Brake Booster noise
 

Glad you got the problem sorted out but i have a question for you, maybe your video would have answered the question but the vid is down now.

You mentioned running new hard lines to the front and rear and front rubber lines. Did you add rubber lines to the rear calipers? in order for the caliper to float they also need rubber lines coming off the calipers.

Re: Brake Booster noise
 

Yes, new rubber hoses from hard lines to calipers.

Re: Brake Booster noise
 

Ok great

Re: Brake Booster noise
 

I just saw this thread and was about to suggest your CPP booster was the problem. I'm on the 3rd one and it's leaking. Does the last photo you posted show the Tuff Stuff booster?

:gmc2:

Re: Brake Booster noise
 

Yes it is. It has a really nice finish on it.

Re: Brake Booster noise
 

Thanks. I order one from Summit last night. I've had so many issues with CPP Boosters and Masters cylinders.

:gmc2: