[Hydratech®]

It sounds to me like you still have some brake bleeding issues or possible MC pushrod mismatch issues (most likely bleeding issues though). One of the best methods of determining where the problem could be is to buy some appropriate port plugs for the MC. Yank the brake lines loose and cap them with vac caps, then plug the ports on the MC. Now go apply the brakes with the engine off and see what you get. If the MC is bled properly and you have the MC pushrod interface setup properly, you should have very little pedal travel before being met with a brick hard pedal (as the fluid simply has nowhere to go with the MC ports plugged). If you cannot get a hard pedal with the MC plugged, then the MC in play has obvious issues. You will most likely find that it passes the MC port plug test, and the next move would be to only connect the front brake line. Since you have only the front brakes hooked up, you will be able to clearly see if the fronts are pressurizing up correctly during brake apply - if they aren't, bleed them as needed. Once you have the fronts situated, then connect the rear line and see what happens. Typically the rear circuit is where most find the culprit...

We have thousands of customers succesfully running the T fitting return line arrangement, and it works just fine unless you have a super mega flow pump (like some offroad apps). The best answer is to run twin low pressure return line nipples though. Note that in most GM applications running a Saginaw P series, that a simple housing swap to a factory hydroboost specific reservoir is reasonably simple, though the housings can be tough to locate. Spanking the housing off and introducing a second return nipple is also a reasonable proposition, though you have to watch the heat you apply to the thin sheetmetal to make sure you don't warp it. If introducing a second nipple, run the steering return line to the factory nipple, as it has been engineered / carefully targetted in the reservoir to prevent the pump from possibly sucking in any air circulating though the PS system. Since the return line from the brake assist unit will only flow when you release the brake (about a tablespoon of fluid will exhaust during brake release), you may target a second nipple anywhere you like in the housing. We have tested some various types of directional flow check valves in experimental exercises to find no merit, and actually found them to be too ratchety in their operations (which can cause more trouble than good). PCV valves are never a full shut off device - more so a variable flow device based upon vac levels = don't bother even trying this...