Leaky Master cylinder / booster interface - wtf

[slamFJ60]

I had a leak betwixt the master cyl & booster on my 83 FJ60. Easy to see b/c the fluid ate the paint off the booster. I pulled it apart, cleaned up to two surfaces and put a new seal & new rubber boot on the master cylinder but it still leaks. Did I miss something? WTF? Is it the seal or the boot that actually keeps the fluid in...?

I will take it apart again & clean it, again - the old seal had to be chiseled off - but has anyone else run into this? Is there some magic? I can't imagine what else to do.

thanks

 

[Jan-78FJ40]

I had a leak betwixt the master cyl & booster on my 83 FJ60. Easy to see b/c the fluid ate the paint off the booster. I pulled it apart, cleaned up to two surfaces and put a new seal & new rubber boot on the master cylinder but it still leaks. Did I miss something? WTF? Is it the seal or the boot that actually keeps the fluid in...?

I will take it apart again & clean it, again - the old seal had to be chiseled off - but has anyone else run into this? Is there some magic? I can't imagine what else to do.

thanks

If you check the FSM, you'll see that there are multiple seals. From your description it looks that you only changed the most outer one. Probably some of the inner ones are leaking as well, and that presses the fluid out.
You can get arebuild kit for the master, that has all the seals. BUT, if you go that route, get a honing tool as well, otherwise your cylinder will leak again in a few months.
The real solution to this is a new master.
j

 

[lowtideride]

Are you replacing the plunger on the MC (its only a few bucks) or just the paper seal between the boost and the MC? The plunger is the part that needs to be replaced.