New Master Cylinder Defective?

[JasinC19]

Hey guys,

I just attempted to bench bleed my new master cylinder (93 cobra from americanmuscle.com)

Manually pumping on the bench does nothing. To double check myself, I installed it on the car and pumped the brakes repeatedly. I feel resistance, but none of the fluid in the reservoir gets pumped out.

The same procedure with the old MC shoots nice green gooey brake fluid out the side.

I removed the plastic plugs and the fluid level is max.

I wanted to make sure I didn't miss something basic before dealing with AmericanMuscle for a replacement.

Thanks,
Jason

 

[Mustang5L5]

The plastic plug method isn't the best IMHO.


What i do is buy two 99 cent premade brake lines that fit the two ports on the MC. I forget the two sizes needed unfortunately. I then bend then into a 3-sided square and cut off the excess so that the end of the tube sits inside the MC reseviour UNDER the fluid level. Snug up the lines, fill the MC with fluid above the ends of the tube and pump away. Does the trick in a few pumps.

 

[JasinC19]

So you don't think I have a defective MC? Should the MC pump fluid out even when there is nothing connected to the ports?

 

[Mustang5L5]

You gotta prime it first. If it's bone dry and you just pump it with the ports open, nothing will come out

 

[JasinC19]

So somehow having the lines in there will open a valve or something and allow the fluid to come out? The plastic plugs supplied had no holes in them. They were just plugs so i though I'd just shove plastic hose in the ports lol.