orange plugs in master cylinders

[prkaye]

The orange plugs that are in the master cylinders - these prevent the cylinders from opening and closing before they are hooked up, and prevent debris from getting in?
Is there any reason why I can't take these out temporarily to try out the movement of the pedals with the master cylinders bolted in-place? Or best I wait until the brakes and stuff are all connected? Will it hurt the master cylinders to open and close them without them being connected to brakes?

[Rick S.]

The are just dust caps, to prevent FOD, junk, dirt etc. from entering the cylinders, IMHO you can operate them but I advise against until there is sufficent oil to keep the piston/cylinder from running dry on each other.

[mannanj]

A drop of hydraulic fluid on both sides of the "O" ring in the Cylinders will suffice in keeping them happy while you sit in the cockpit making airplane noises. Just make sure you keep any trash etc out by re-capping them or installing the brake hoses.

[prkaye]

Actually, could someone explain to me how the master cylinders work? I realise this is a naive question, but I only have a vague notion of how this works... when the cylinder is compressed this creates pressure which forces hydraulic fluid down a brake-line which causes the brakes to operate. There are two ports on each cylinder... I'm guessing one is for the brake line that goes off to the brakes. Is the other port to connect to a reservoir of hydraulic (brake) fluid? Which port is which? Do the cylinders come already loaded with hydraulic fluid, and will this squirt out if I compress the cylinders now (not hooked-up)?

Sorry, a bunch of naive questions here, but my master cylinders didn't come with an instruction sheet, and I'm totally new to this stuff.

[Mike S]

Originally Posted by prkaye

but I only have a vague notion of how this works... when the cylinder is compressed this creates pressure which forces hydraulic fluid down a brake-line which causes the brakes to operate.

Correct.

Originally Posted by prkaye

There are two ports on each cylinder... I'm guessing one is for the brake line that goes off to the brakes. Is the other port to connect to a reservoir of hydraulic (brake) fluid?

Again, correct.

Originally Posted by prkaye

Which port is which?

The port closest to the piston push rod is supply, from the reservoir.

Originally Posted by prkaye

Do the cylinders come already loaded with hydraulic fluid, and will this squirt out if I compress the cylinders now (not hooked-up)?

No, it is not loaded, there might be a bit of fluid from assembly, and testing, but you will need to fill it yourself.

This is the last step in the brake plumbing------after everything is hooked up, you will force brake fluid into the bottom of the system, and out the top. This is called "bleeding" the brakes.

Lots of prior threads on bleeding, try searching for tips using a garden sprayer.

Good luck.