Originally Posted by TX Tahoe Z71

Had the same problem and just spoke with Van from Vanco Power Brake Supply (an expert on hydroboost systems).

He said if your brakes are dragging and you have separated the master cylinder from the brake booster to identify that it is indeed the hydroboost causing the problem (not kinked brake line, old calipers or something else), there are two likely causes:

1. The pedal rod is too long. To diagnose, disconnect the rod from the pedal, then start the truck, if it has stopped dragging, then you need to put spacers in between the brake booster and firewall to space the rod out appropriately.

2. There is resistance in the low pressure return line. It is either blocked, kinked or just isn't flowing well. To diagnose, disconnect the return line and let it drain into a bottle while the truck is running (shouldn't be a gusher, just a trickle of fluid). Plug the connector to avoid fluid spilling. If this fixes it, then that is your problem. If it is T'ed in, then the straight part of the 3/8" T fitting should go from hydroboost to reservoir and the steering box line should be at a 90* angle as it is less sensitive to flow resistance (this is likely my problem, haven't fixed it yet b/c I just found this out today). Another problem is that the T is overclamped and flow is being blocked with the hose clamps. Or, the hose could be old, too small or kinked. He said that the power steering pump should not cause your brakes to drag, so don't haul off and replace that first without testing these things out.

In the picture above, it looks as though the problem was that the T fitting was set up wrong with the 90* fitting going to the hydroboost instead of to the steering box.

Hope this helps someone else. I couldn't turn anything up about it. (yes I know this thread is 3 years old)

Originally Posted by nonnieselman

i had the 2500HD PS pump, bracket, and reservior from the LQ4 when i bought it.. so when i did HB swap i just bolted it on and went.

only other thing i see helping is a Y fitting instead of a T fitting.

Originally Posted by TX Tahoe Z71

Had it for a couple of years, then it started leaking from the T a bit ago, just dripping, so checked the clamps and tightened them up a bit, but kept dripping. So I took a razor blade, cut about 1" off all three hoses to give the clamps a fresh surface, bought 3 new clamps and now it has stopped leaking, but the brakes have started dragging. Thought it was the fluid level, so sucked some out, added some, sucked some out, nothing has worked.

Since the only thing that has changed are the clamps and some thicker Lucas no-leak power steering fluid (though I have diluted it with regular stuff now that the leak is fixed), I am convinced it has something to do with the return line.

Van was convinced that the reason they're dragging is the way the T fitting is configured (but that's how it has been from day 1, so I'm confused why it just now started unless I have overclamped the clamps, but they were just hand tight, nothing crazy tight). I'm going to switch it today or tomorrow and post back up. If that doesn't fix it, I'll switch and T in after the cooler like you and SilveradoXD said.

Originally Posted by GMCtrk

You're problem is definitely how you have the hydro return hose plumbed in. I've seen this problem posted on other forums as well. The reason for the leaks is probably because your on the high pressure side. The low pressure return side has very low pressure.