Finally located the source of a slow brake fluid leak in my 1977 FJ40. Leak appears between the master cylinder and the booster. Has anyone had this happen? Not sure how involved it might be to fix.
Brake Fluid Leak
- Thread starter t53c50
- Start date
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pb4ugo
SILVER Star
You need to rebuild or replace your master cylinder. It's leaking out the m/c piston into the booster.
Depends on the damage to the MC, a kit might not fix it - the whole unit isn't all that pricy. Second make sure the booster isn't leaking vacuum or it will make cylinder 5 run lean and cause $$$ damage.
Your master cylinder is leaking as other have said out the back into the booster. The kits are readily available from Mr T and there are some threads on here with good pics and instructions on how to rebuild.
Also as others have said, brake fluid tends to not play nice with the booster diaphragm rubber so if it's been leaking a while, you might want to replace it or have one on hand.
Also as others have said, brake fluid tends to not play nice with the booster diaphragm rubber so if it's been leaking a while, you might want to replace it or have one on hand.
pb4ugo
SILVER Star
Rebuilding a mc isn't really difficult. B4 you order a kit you should take it apart and get a cylinder hone for your drill. Clean the bore and hone it. Then check the bore and see if it cleans up. They tend to get low spots in the bore. If they're bad it may not be rebuildable. @cruiseroutfit s will set you up with what you need. Kit or m/c.
- Thread starter
- #7
Good to know. I'll check that right away.
- Thread starter
- #8
I'm assuming the piston seal nearest the booster is the culprit. Is that a fairly common issue?
pb4ugo
SILVER Star
Usually they leak from the rear. The low spots in the bore are usually on the bottom.
