So I disconnect my abs module to repair a power steering leak. Put everything back together and brakes are real spongy. Took it to dealership and I think they may have put it to me.
Said they bled the system and that my master cylinder is bleeding back into my booster. Quoted me 1500 bucks to repair it.. brakes are same as when I took it there Got home cut the car off and took the vacuum line off brake booster and it has plenty of suction..... wouldn't it not have suction if the booster was bad?

 

No, the suction is from the engine and should be there when the engine is running.
What the dealer is saying is that the master cylinder is leaking past its input shaft seal and bleeding pressure into the booster. Unbolt the master from the booster and see if you see brake fluid in the booster.
Were you low on brake fluid when you took it in? That fluid should have gone somewhere.
When you "disconnected" the ABS module, do you mean you broke the brake lines and removed the module? or do you mean just disconnected the electrical connector? Air in the ABS module is bled by cycling the module with a Tech 2. Sometimes air is very stubborn and takes a little to get it all out.
Good luck and let us know what you find.

 

lowflier is correct - if the Master Cylinder is leaking - one of the places it can leak from is a seal that keeps fluid in the cylinder bore. If that seal fails - the fluid can get into the brake booster.

So - you have some options here...

If you Just disconnected the electrical connection to the ABS module - no air got into the system. So - if the brakes are spongy - you have a hydraulic issue somewhere in the system. You need to figure out what the problem is and resolve it. Replacing the Master Cylinder is a roughly 1 - 1.5 hour job, and the new master is probably about $200 from the dealer. Then you need to do a brake bleed (see below).

If however - you did disconnect any brake lines - you almost certainly got some air into the system, and it's quite possible that a good brake bleed will resolve the problem. Head to another stelership, and tell them that you want them to do a full brake fluid flush including the ABS module. This should run about 1 hour (maybe 1.5) - and about $10 to $20 in parts (brake fluid).

If you have a leak in the master cylinder - the fluid in the reservoir should be dropping as you use the brakes. You could park the ground on level ground, and make a mark at the current fluid level in the reservoir - and see if it falls... If the fluid level stays constant - then the odds you have a leak are LOW !!!

Even if the dealer is replacing both the Master and the Power Booster - and doing the full brake bleed - $1,500 seems more than a little bit high.

As lowflier stated - the right way to do a full brake system bleed involves utilizing the Tech II do cycle the valves in the ABS unit while the system is being bled - but some of the better scantools also have this capability as well, so this job does not need to be taken to a Chevy dealer - a good independent can probably do the job - and may be a LOT less.

 

I totally disconnect the abs module. That's why I took it to dealership is somthey can put the tech2 on it. But.... according to them they have bled everything now its the booster and master cylinder gone bad. Everything was perfect before I removed module.

 

OK - So you had the brake hydraulic system open, so it's Highly Likely that air got into the system - hence the spongy pedal.

So - if you're saying that the stealership tried to do a full system bleed - and that they were unsuccessful due to what they believe is a leaking master cylinder, then that's one thing. If that is the case - I would look to bring the car to either another stealership to get a price for a Master Cylinder replacement and a full bleed, or to a competent independent to do the Master Cylinder replacement, and either have them do the full bleed (if they have a tool that can activate the ABS valving) - or return it to another Chevy service dept. for the bleeding.

If the stealership didn't try to do the full bleed - saying that they need to replace the Master Cylinder first - I'd recommend taking the car to a different dealership, and seeing if they can attempt the full bleed. Remember - the Tech II that the Chevy service departments use is the same for all the GM brands - so a Buick, Cadillac, or even a GMC service dept. will have the ability to do the full system bleed for you.

Again - $1,500 just sounds way high to me....

 

I was thinking of tackling the master cylinder job myself. I was looking at the oring kit. I'm going to take the master cylinder off today and check to see if any fluid is in the booster

 

Took master cylinder off break booster. Had suction. Checked O ring and it was fine. Cleaned connection and replace. Took cat for a spin. Same thing. The car does seem to jerk to the right when I press brakes. Still thinking air is in the line.

 

So now you know that the dealership did not know what they were talking about and was trying to steal your money. That or you got stuck with a world class incompetent mechanic. That guy would not last very long at my shop...
Either way, it just sounds like you need to find someone to cycle the ABS module to get the stuck air bubble out of the brake system.
My old Snap-on MODIS scanner will cycle the ABS system, so any good shop should be able to do it. Like I said, air stuck in the module is very stubborn to remove. Lots of places to get stuck.
Good luck and keep us posted.

 

It sounds like you got a moron for a mechanic. You have air in your braking system. Find another place and explain completely to the mechanic what you did. Jfyi It is possible that the master is leaking internally but highly unlikely.