Master cylinder leak

[David H.]

I cant seem to stop the connection at the front of the master cylinder from leaking. I put in all new parts, the big nut and copper washer, the brass block and two new copper washers and even the bolt. Now it leaks more than it did before. What is the torque for the big nut? What is the torque for the bolt? I've just about had it with this. Any ideas would help.

[Edward J.]

Re: Master cylinder leak

Dave, sometimes it really takes some torque to get new coppers washers to seat properly, I seen posts like this more than a few times here. I work in a Automotive shop and see this quite often on disc calipers. don't be afraid to give it an extra pull with the wrench. Also make sure the copper washers are the correct diameter.

[Bob H.]

Re: Master cylinder leak

David,

Before tightening it again, I would lightly lube the bolt. It may help cut resistance when you tighten it. I did have to exert some pressure on mine as well

[David H.]

Re: Master cylinder leak

This is a picture of the setup i used to tighten the big nut against the copper washer. I was afraid i was going to break something. A standard 1/2" ratchet with an 11/16 boxend wrench for more leverage. I really reefed on it. I give up!!!

[Edward J.]

Re: Master cylinder leak

Dave, have you compared the parts you are replacing to the ones you took out ? Is the bango bolt have the correct number of threads, lenght ? copper washer thickness. brass block same thickness? Food for thought. can you re-install the old parts and check?

[David H.]

Re: Master cylinder leak

Here's a picture of the old and new setups. All the same except the wider copper washer on the large nut.
I have re-assembled it tonight using permatex thread seal with teflon as i saw in an earlier post about this problem
Hope it works.

[David H.]

Re: Master cylinder leak

The permatex thread sealer seems to have worked. When bleeding the brakes there was one tiny bubble that appeared for a moment at the large nut but then went away and did not return. I have a very good solid pedal. NAPA auto has the thread sealer with Teflon.