kewpie79

replaced the master cylinder, bled the brakes, pedal still goes all the way to the floor. Any ideas?

darkfrost

iTrader: (1)

Did you bench bleed the master cylinder before installing?

Does it always go straight down to the floor? or is there a hard spot first, then it sags?

If it goes straight down, check the locknut and lever at the brake pedal and adjust it as necessary.

kewpie79

engines off, the pedal stops then sags, engine on goes straight to the floor

LongDuck

Check the slave cylinder for leaks - remove the rubber 'boot' around the fork pushrod and if hydraulic fluid comes out, you're just pumping it out of your new master through the slave.

Always replace both parts at once unless you've identified a bad seal or rebuild. When you 'upgrade' with a new part, you're increasing the load on the remaining old parts, and furthering their impact as the weakest link.

Check there, if not the slave leaking, you may have a bad proportioning valve within the brake master. These are the plastic cups that keep the fluid from backflushing into the reservoir when you apply brakes. HTH,

Kentetsu

Holy Cow LongDuck! I think I finally caught you in a mistake! (his post implies that he is talking brakes, while you are talking clutch). LOL.

Kewpie79, I've read some other posts along these lines. Replacement of the BRAKE master cylinder can be a real pain sometimes because they do not always prime themselves correctly. I would recommend that you pick up a vacuum/pump tool from one of the local parts shops (I think I paid around 20 bucks for mine). These are mainly used for pumping fluids, or diagnosing vacuum issues. The good ones can be used to pump the fluid in through the bleeder, so that it fills up the master cylinder. This "reverse bleeding" should take care of your problem.

Otherwise, just keep going through the bleeding process and you might get lucky.

84gsNC

Im having brake issues right now. My pedal is firm at first and then sags. I was thinking it was the master cylinder. It just started up one day out of no where so I dont think I have a leak in a line or anything and Im not losing fluid. just lookin for some thoughts

sgieldon

Just a Thought!!!!
There is a 2 way Valve that is inserted in the Vacuum Line attached to your Brake Booster that goes From the Booster to the Engine.
You might want to check that to make sure the Arrow on the Hose is facing towards the Engine or that it is Closed or Open depending on which way you Blow into it.

Just a Thought!
sgieldon

darkfrost

iTrader: (1)

Yes, its the master cylinder. Happened to me recently too.