Bone dry
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Postmaster
Joined: May 2004
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Bone dry
I lost the power boost in my brakes a few days ago. Opened up the master cylinder and the smaller chamber had no brake fluid...bone dry. The larger chamber was almost to the top. I filled the empty chamber and brakes work fine now. Looked around each wheel.... no evidence of fluid. Where'd it go??
Fleet Mechanic
Joined: Nov 2003
Posts: 1,372
Likes: 14
From: West Cornwall, CT
There could be a slow leak in one of the rear brake cylinders and it might not be seen on a quick check. It is possible for brake fluid to leak from the master into the power booster.
The fluid has to go somewhere. It might be time to pull the rear wheels and drums (your truck has rear drum brakes i think) and do a detailed inspection.
Lou Braun
The fluid has to go somewhere. It might be time to pull the rear wheels and drums (your truck has rear drum brakes i think) and do a detailed inspection.
Lou Braun
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Postmaster
Joined: May 2004
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I checked the rear as you suggested. The rear linings, original 25 year old ones, are disintegrating into pieces. See if this makes sense....since the linings are almost gone the fluid in the rear circuit is pushing the rod in the rear cylinders out further and further, so that the fluid level up top has disappeared. Sound right? If so, why would the power boost not work?
Lead Driver
Joined: Jun 2005
Posts: 8,475
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From: Calgary Canada
It's also possible for the fluid to transfer from one side to the other is the seals in the MC aren't sealing properly. I had a car that did that. I had to keep a really close eye on it and transfer some fluid back once in a while until I replaced the MC.
Fleet Mechanic
Joined: Nov 2003
Posts: 1,372
Likes: 14
From: West Cornwall, CT
If you check under the dust covers on your rear brake cylinders, you will probably find that they are the source of the leak.
It sounds like a brake job is needed. Turn the drums and install new rear brake shoes and cylinders. This will probably last for another 20 years.
It is possible that the master cylinder is also leaking. These are relatively easy to replace. Bench bleed the master if you replace it, then bleed the whole brake system. Doing a large brake bleed will also flush out that 20+ year old brake fluid.
Lou Braun
It sounds like a brake job is needed. Turn the drums and install new rear brake shoes and cylinders. This will probably last for another 20 years.
It is possible that the master cylinder is also leaking. These are relatively easy to replace. Bench bleed the master if you replace it, then bleed the whole brake system. Doing a large brake bleed will also flush out that 20+ year old brake fluid.
Lou Braun
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