Brake booster replacement; brake pedal slow to return

[InspectahDEck]

I have had a PS fluid leak from of 05 yukon for some time, where the leak is coming from the bottom weep hole on the brake booster unit. I purchased the replacement gasket set, but that ultimately started leaking again as well. I decided to purchase a reman brake booster unit (Cardone 52-7370). After installation, there is no leak, but the brake pedal is very light, and is slow to return. Takes about 15 seconds for it to fully return.

When replacing the gasket set in the past, I never had to bleed the brakes. Is this something that needs to be done after a full brake booster unit replacement, or is this a defective product possibly?

When installing the brake booster, I simply disconnected the two bolts from master cylinder, leaving all hoses and attachments in tact on the master cylinder. Have confirmed everything under the dash is connected properly and nothing interferring with the brake pedal returning.

Any thoughts appreciated

 

[nonickatall]

Maybe the brake booster needs to be bled? I assume you have the hydro boost system that works with hydraulic pressure.

If you can't bleed the brake booster, I would loosen the screws again, brake a few times and then tighten the screws again. Maybe it's just a little tension?

If you don't disconnect the lines from the master brake cylinder and it doesn't run empty, you don't have to bleed the brake system.

 

[B-train]

Agreed with bleeding it. The slow return does sound like you have an air spring in there. I would try 2 things: 1st with engine off run the pedal down and up slowly multiple times (don't bottom it out) and see if the slow steady movement helps bleed it and hopefully make a better feeling pedal. Then start it with boost and try again. 2nd: try a slow test drive and see what your brakes feel like. Do they continue to drag after release? Or do they release, but the pedal is slow to return. In theory I would assume they continue to drag until the pedal is at rest

I know on rack and pinion cars it works well to jack up the front wheels and run the gear side to side with the engine off multiple times to burp the system. When doing it under pressure it seems to not bleed correctly and make the pump whine.

If you still have no success, you may have a defective unit that is bleeding pressure off internally or something like that.

One last thing you could try is blocking off the ports and pushing the pedal with engine off and see what it feels like. Similar to a master cylinder block off test.

 

[InspectahDEck]

Am I missing something? The Cardone part is completely missing the spring + pin, not sure what it's called. Take a look at the pics

 

[nonickatall]

There is something wrong. You have the wrong brake booster, or the brake booster is missing these parts.

Are you sure that is the right part?

 

[InspectahDEck]

Just gave Cardone a call, they said I need to use the parts from my original unit. I did this and everything is working fine now. Guess i should of looked at the new unit harder before hand, comparing it to the original, or at least an instruction informing of this

 

[Fless]

Whew! Glad you have a solution.

 

[OR VietVet]

Guys hate to read instructions! Should have had a female with you to help.

 

[BlaineBug]

Perhaps they need to put something with a yellow sticker that specifies that original parts must be re-used.

 

[rockola1971]

Perhaps they need to put something with a yellow sticker that specifies that original parts must be re-used.

Or maybe they figure grown men will act like grown men and do the job from experience or atleast use a haynes/chiltons manual.