brake mc orientation?
Thread Starter
|
Junior User
Joined: Feb 2009
Posts: 63
Likes: 0
brake mc orientation?
My 79 F250 had a leaky master cylinder when I got it, and exhibited some serious rust as a result to the booster can. So I bit the bullet and replaced both w/ new parts.
In the process I removed the bracket on the firewall since I couldn't reach the bolts when in-place. Bolted back up, the master cylinder sits with a tilt downhill toward the firewall. I assumed this was okay when I installed it because it made the push-rod line up so nicely with the brake pedal.
Unfortunately, the new master cylinder leaks, as well, I think at the gasket seal on the lid, in the front half. This is causing an exact replica of the original problem-- brake fluid running down the slope that is rusting out my new booster can.
Should my master cylinder sit perfectly level? This would lead to a leak being less likely to run onto the brake booster, but would it not also change the alignment with the pedal/rod connection? Also, is there anything to paint the can with that might neutralize the corrosive quialities of the brake fluid if it should start leaking again before I find/stop it?
In the process I removed the bracket on the firewall since I couldn't reach the bolts when in-place. Bolted back up, the master cylinder sits with a tilt downhill toward the firewall. I assumed this was okay when I installed it because it made the push-rod line up so nicely with the brake pedal.
Unfortunately, the new master cylinder leaks, as well, I think at the gasket seal on the lid, in the front half. This is causing an exact replica of the original problem-- brake fluid running down the slope that is rusting out my new booster can.
Should my master cylinder sit perfectly level? This would lead to a leak being less likely to run onto the brake booster, but would it not also change the alignment with the pedal/rod connection? Also, is there anything to paint the can with that might neutralize the corrosive quialities of the brake fluid if it should start leaking again before I find/stop it?
MSEE
Joined: Apr 2004
Posts: 10,386
Likes: 35
From: Austin, TX
The MC doesn't sit level. This is one of the reasons you have to bench-bleed the MC out of the truck when you install it, because it has to be level when it's being primed. If yours is leaking past the lid, it's overfull.
Thread Starter
|
Junior User
Joined: Feb 2009
Posts: 63
Likes: 0
My mc is leaking down to the point of a mushy pedal, at which point I have to refill it, so does that mean I've got a leak elsewhere in the system? The front section of the master cylinder is for the read (drum) brakes, isn't it? I can't see any other point in the system that looks wet--wheel cylinders, line connections or anything.
Elder User
Joined: Jun 2008
Posts: 572
Likes: 0
From: Duncan B.C.
All my '78 &'79s sit tilted back, ('73-'77s sit level), but none of them leak out the lid. I sounds to me like you have a poorly fitting lid/seal. There will always be fluid splashing up there either through vehicle motion or the " gusher" effect that happens when you use the brakes. We've all seen what happens when you forget to put the lid on while bleeding the brakes, right? So if it's leaking out there either the seal/lid/sealing surface is bad or something is causing the thing to over pressure some how. I don't know what would do that. Maybe a plugged vent hole on the lid?
Senior User
Joined: Dec 2005
Posts: 229
Likes: 1
From: Fargo, ND
hope this helps
I too had this same problem that you are having on my 78. I found two things that have helped the problem, but not necessarily solved it. First when bleeding the brakes I found that on the proportioning valve there is a little rod that needs to be pulled out and held out when bleeding (at least on the F150 4x4). This helped my problem significantly and secondly I also used a big hose clamp around the MC to keep the cover tight. It seemed like the bail clamp wouldn't clamp it down tightly enough. So far it hasn't leaked, but I haven't driven it much in the past month so its hard to tell. I hope that this helps you.
