The rear reservoir would be for the front brakes. Unless you mean the reservoir for the rear brakes when you say rear reservoir.

Neither reservoir should be pressurized. The pressure should only be created by the pistons in the MC bore.

If you had moisture in the brake fluid it wouldn't be a surprise to have corrosion in the bore after 6 years. Then when you pushed the pedal to the floor you might have damaged the rubber seal inside.

So, loose fitting allows reservoir ro leak dry, pedal goes to floor because of it, damaging MC seals, new MC leak looks like old fitting leak. Should have got that fitting tight the first time. Seems like it was very loose. Oh well.

17 hours ago, chaseincats said:

I noticed the bolt that screws the rear-wheels' brake line into the bottom of the master was wet and could be tightened a good 3/4 turn

17 minutes ago, Zed Head said:

The rear reservoir would be for the front brakes. Unless you mean the reservoir for the rear brakes when you say rear reservoir.

Neither reservoir should be pressurized. The pressure should only be created by the pistons in the MC bore.

If you had moisture in the brake fluid it wouldn't be a surprise to have corrosion in the bore after 6 years. Then when you pushed the pedal to the floor you might have damaged the rubber seal inside.

So, loose fitting allows reservoir ro leak dry, pedal goes to floor because of it, damaging MC seals, new MC leak looks like old fitting leak. Should have got that fitting tight the first time. Seems like it was very loose. Oh well.

Sorry, I was referring to the reservoir for the rear wheels when I said 'rear reservoir.' Alright, so hopefully the new master fixes the issue. I just don't understand how both wheel cylinders and the master all went out at the same time...

Do you think the positive pressurization in the reservoir is due to the possibly blown seal in the master?

Some copper flare washers can seal metal to metal connections.

No, Pretty sure you’re MC is bad