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1989 Brougham d'Elegance, 1992 Sedan DeVille
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Discussion Starter #1
I just replaced the calipers and a couple of brake lines on my '89 Brougham and have yet to fully bleed/flush the braking system.

There is obviously air in the brake lines, so that's not my question but, I found that after I had replaced the leaking lines and tightened everything down, the master cylinder now produces a metallic clicking sound when the brake pedal is depressed that can be heard through the firewall. The volume of it depends on how hard the pedal is pressed, but it only has to be pressed down a few inches before it clicks. Is this normal? There's very little fluid in the braking system and obviously air in the lines, so is that to blame or has something gone wrong during the repairs?

It's giving me a lot of anxiety, because I obviously want to ensure that everything is seaworthy before flushing/bleeding the lines. Can anyone instruct me or otherwise put my mind at ease? Cheers.
 

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1970 Coupe De Ville//Cessna 172
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551 Posts
The first thing you need to do is bleed everything. I know you want to wait, but why? Secondly, you need to diagnose your problem. Eliminate everything possible. It all works as a system.
Jeff
 

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1989 Brougham d'Elegance, 1992 Sedan DeVille
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42 Posts
Discussion Starter #4
The first thing you need to do is bleed everything. I know you want to wait, but why? Secondly, you need to diagnose your problem. Eliminate everything possible. It all works as a system.
Jeff
I suppose I just wanted to get an idea of how serious/harmless/ambiguous this prospective problem is before wasting a lot of brake fluid and possibly having to disconnect everything again. I'm not entirely sure where the sound is coming from within the master cylinder but, more than anything, it sounds like the piston is lagging or clipping against something.
Did you bench bleed the master cylinder before installing it?
I haven't even touched the master cylinder itself. The only bits I've installed/replaced are calipers and the two brake lines that connect to the master cylinder. The clinking sound didn't emerge until everything was reconnected and pressure was returned to the lines. Does the disconnection of the lines at the master cylinder mean I'll have to bench-bleed the air from the piston?
 

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1980 FBC
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979 Posts
I didn't read your original post properly. Lack of sleep.

New master cylinders are easier to deal with if bench bled upon installation. You didn't change yours so this does not apply. Duh. Sorry.

Your clicking sound is most likely imbalance in the front and rear hydraulic systems forcing the proportioning valve off center.

The system should be fine when fully bled. If it were me I'd gravity bleed/flush the heck out of it. The process takes a lot of time but works with only one person and should get rid of the click.

Crack open a bleeder, top off the master and see if the level drops after 10-15 minutes and/or you get fluid from the bleeder. If not there's way too much air in the system or the proportioning valve is way off center. A little but of suction on the bleeder can help start things in very stubborn situations.

Fish tank hose is good because you can see what's going on.

The final step in gravity bleeding is to close bleeders and stomp on the brake pedal, then go around bleeding each at least one more time. Gravity bleeding works as well as pressure bleeding when done properly but the last part is necessary because air bubbles inside a casting like calipers won't go away without pressure at some point.

Next time do not even press the brake pedal until after gravity bleeding and the process will go much faster.

I hope this makes sense. I'm working on a very high profile project at work and the other people are genius/professor types who can't tie their shoelaces.
 

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1989 Brougham d'Elegance, 1992 Sedan DeVille
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42 Posts
Discussion Starter #6
Thanks Ape; Very helpful. I've already got some fishy tubing and everything else needed for the operation, so I'll get on it as soon as I can and report back if I have any further woes.
 
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