Power booster

[69furyIII]

Not to long ago my power booster went bad, I sent it put to get rebuilt, then got it back and installed it. But my question is, when you replace the booster should you bleed the master cylinder even though I didn' remove the brake lines.

 

[Davea Lux]

Not to long ago my power booster went bad, I sent it put to get rebuilt, then got it back and installed it. But my question is, when you replace the booster should you bleed the master cylinder even though I didn' remove the brake lines.

As long as the brake lines were not disconnected, you do not need to bleed the brakes. Check the master cylinder carefully to be sure it is not leaking out the back into the brake booster, that is usually what causes the booster to fail. If you observe leakage from the master, replace it now before it messes up your new booster. If you have not already done so, replace the vacuum hose from the manifold to the booster, especially if you vehicle still has the OEM hose installed. Be sure to use vacuum rated hose as a replacement as fuel line or transmission cooler line hoses will not work for vacuum applications.

Dave

 

[DocMcNeedy]

I had same problem on my Imperial. I decided to go with new master and rebuilt booster...think my master was 75-100 bucks.

 

[DocMcNeedy]

Just found a pic of the combo before install.

 

[CBODY67]

When I've replaced master cylinders, I've been lucky to NOT need to bleed the brakes. Reason is that with minimal fluid loss, the fluid is heavier than the brake fluid, so any "air" in the lines will be at the top. Once the cylinder is filled and moves fluid, reconnecting the lines and some short and quick pedal depressions (in rapid succession) will usually put a negative pressure on the little air space in the lines, letting the new fluid replace it. The air then exits via the master cylinder reservoir. NO need to even get close to the wheel cylinders, which would only serve to pull the small amount of "air" up top down through the system, possibly causing more issues than it was meant to in the process.

In changing a line, pulling a vacuum on the master cylinder would work, too. Just that few people can do that.

At the assembly plant, they first pull a vacuum on the system via the master cylinder (via an overhead apparatus that attaches to the top of the master cylinder. Once the vacuum is stabilized, then the fluid all goes in at once. Same with the coolant and possibly the power steering fluid.

CBODY67

 

[ayilar]

I had same problem on my Imperial. I decided to go with new master and rebuilt booster...think my master was 75-100 bucks.

Doc, where did you buy them? Brakes are the first thing I want done on the car I just bought, and I may need to do what you did.

 

[DocMcNeedy]

Doc, where did you buy them? Brakes are the first thing I want done on the car I just bought, and I may need to do what you did.

I'll check my receipts since I had the booster rebuilt and master replaced in July last year. All the resources in my head and I forgot the name off the top of my head.

 

[DocMcNeedy]

Before and after. I'm still checking for name of resource.

 

[ayilar]

Thank you -- really appreciate the help. Look fwd to the info!

 

[DocMcNeedy]

Thank you -- really appreciate the help. Look fwd to the info!

Midwest Power Products, Morris, IL
Just checked my cost for everything was $352.72 for rebuilt booster and new master.

 

[ayilar]

Super, thank you. Did you send them your parts for remanufacturing, or did you get new pieces? If the former, how long did they take to remanufacture your parts?

 

[Big_John]

Another option. Never used these guys myself, but have heard good things.

Booster Dewey Power Brake Booster Exchange Inc.

 

[DocMcNeedy]

Super, thank you. Did you send them your parts for remanufacturing, or did you get new pieces? If the former, how long did they take to remanufacture your parts?

I sent them the old parts...they rebuilt my booster and sent back old master and gave me a new master...I recall roughly 4 weeks from shipping to delivery.

 

[DocMcNeedy]

Btw...longest 4 weeks of my modern life...I wanted so bad to drive Big Red since she was undrivable with failed brakes from the moment I got her off the trailer from Illinois.

 

[ayilar]

Good to know. Will let my restorer know, in case we need to redo them.