Just an update,I checked the screen inside the resevoir and it was filled with alot of crud so I cleaned it out,took out some fluid and added some fresh fluid.The pedal feels good idling in the driveway but I need to take it for a drive and get it hot to really check it.
The calipers and the wheel cylinders are not leaking fluid.I did break off the bleeder bolt but it was closed and isn't leaking,in fact I did it last summer and it hasn't leaked.I will change the cylinder if I change the master and have to bleed the brakes.It's still bothers me that it only happens in the summer months when it's hot.When it's cold outside the brakes are fine and it doesn't happen.I have done brakes before and have a set of flared wrenches for brake lines.I did a masterand brake lines on my old Porsche, that was a real chore.That was just the opposite the brakes felt great but I was loosing fluid and ended up with a big mess of brake fluid under my carpet by the brake pedal.Thanks again for all the help.

 

To the last post the brakes were having a problem before I broke the bleeder bolt.

 

ok i was bleeding the brakes on mine tonight, and it was a lost cause, it has no air in the line to be sure i ran a quart of BF in eatch line. the same thing almost nothing it was good and drove around the block and back to squar 1 i will try some more tomarrow any luck on it yet from your end?

 

When you replace the master cylinder, you will have to "bench bleed" it before installing.

 

Wow the reponse has been great thanks for everyone's help.I did clean the screen as recomendedand added fresh fluid then took it for a drive in 80 degree heat and it seems to be fine.Hopefully the problem is solved,but if it returns I'll probably replace the master and the wheel cylinder with the broken bleeder bolt.For the person who just replaced the master and bled the brakes and still having a problem check the screen in the resevoir for crud,mine had a fair amount that maybe was blocking the flow of fluid.As far as bench bleeding I never did that in the past when I changed the master and never had a problem bleeding the brakes.If and when I change the Civic's master I'll give it a try.If you do that do you still have to bleed at the wheels?

 

Yes you have to bleed at the wheels anytime the system is opened, such as to replace the master cylinder. Using a vacuum pump bleeding device you can usually forego the bench bleeding of the new master.

 

The reason you "bench bleed" (i.e. prime), a master cyl before installing -
Itis to get the fluid started- because since it is new, the path to where the brake lines connect will be bone dry/full of air)
This way youprevent the piston rodfrom having to be hyper/over-extended - when you pump the brakes the first time after installing -(since it would be trying to pump fluid that isn't there yet - ie the air). If you have "bench bled" it first then you probably won't have to bleed the system afterwards. (assuming that the lines were purged of air already)

All you do is
put on the reservoir
pour in some fluid
And then press the piston rod a few times with your thumb - Do this about 6 times, fluid will gush out of the two holes.
And thats it, you connect it to the booster, the brake lines, etc.and top off

As for bleeding the entire system afterwards-
Most people do, but it is not always necessary, unless you didn't "bench bleed"
So it all depends on wether or not there isair in the system already and wether or not you "bench bled".