Hydroboost Problem
 

Been reading on here for a while and have gotten alot of great info, but now I have a problem. I did the Hydroboost conversion on my 06 1500 ext cab, front disc - rear drum. At the same time, had the rotors turned and put on new pads. A few weeks later, the rotors were warped. Figured that the rotors were too thin after turning and I would just have to wait until I could get the cash to replace them.

The used hydroboost unit was from an 05 2500HD. New M/C (reman), used reservoir. New high pressure hoses and return line hose from Advance Auto. Using original P/S pump.

Fast forward to this past Thursday, replaced the rotors and put new ceramic pads on the truck. Drove ~60 miles round trip, didnt notice a problem. Today on my way up north (about 45 mile trip) I noticed that the truck was shaking going about 45-50 mph. When I got to my stop and check the brakes, the front rims were so hot that I couldnt touch them. They were dragging, but I didnt know it or feel it.

I've attached some pictures of the results on the rotors. I have read the search results on HB from here, but other than a guess at replacing the HB unit itself - I didnt get a clear answer as to what the problem might be. If I cant find out what's wrong, I'm going to have to go back to the original vacuum booster setup until I can. Any help would be greatly appreciated!

http://i834.photobucket.com/albums/z...radoXD/037.jpg
http://i834.photobucket.com/albums/z...radoXD/039.jpg
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could be a caliper hanging up was it both sides? kind of doubt that though , since your truck is so new. id say either master cylinder isnt completely letting pressure out or your hb unit is keeping pressure on the master.

Is there suppose to be a gap between the M/C and the HB unit? Because there isnt one. If I remember correctly, I think that there may have been one when I put it together, but I tightened up the bolts to eliminate that issue. So that might be my problem if the HB is pushing on the M/C. I'll look into that when I get back home, thanks!

no gap is supposed to be there it should together nice and tight.

I know I may be over-simplifying this, but it would seem as if you could jack up the front of your truck to get the wheels off the ground. See if you can spin the wheels with no brake drag, which there shouldn't be. Crank the truck and try and spin them again to see it the HB is affecting the system. If nothing was found in the pervious two checks, I'd hit the brakes and check it again to see if the system is not releasing the pressure once it's applied.

Ok, got home this afternoon. Brakes are definitely dragging but the brakes, rotors and wheels are still quite warm. I will check it later once everything has cooled down completely. I loosened the M/C to see if there was any pressure being applied by the HB unit and found that with the engine off, there was no pressure. I left the M/C loose about 3/16" and started the truck...there is pressure being applied to the M/C while the engine is running. This would explain why the brakes are dragging as the M/C has a constant pressure applied. Am I correct in thinking that there is a problem with the HB unit? Could it be a problem of the brake pedal connecting rod adjustment?

did you swap brake pedals? did your hydroboost come with the longer rod? there are two different rods they come with one is longer and if so it would put presure on the brakes.

Yup, got the new (correct HB) pedal. The HB did come with it's own rod.

No drag once everything is cool. I removed the M/C from the HB unit and started the truck. The internal pushrod slowly extends all the way (at the same time, the brake pedal inside the cab drops all the way to the floor). Looks like a bad seal or some other internal problem with the HB unit. Is it worth trying to fix or just replace with a reman unit? Thanks.

Found the problem. I had originally attached the return line from the HB unit between the gear box and the cooler, this was the problem. There was a significant amount of pressure after the gear box and this was pressurizing the return line - causing the HB unit to apply pressure on the M/C.

So I would recommend to anyone doing this conversion that you either get the correct P/S pump with the 3rd connection OR you connect your return line AFTER the cooler.

Thanks to all that helped.

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. Hydroboost to the reservoir should be in a straight line through the T fitting.

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

Wow, haven't you had hydro for quite a while? I'd imagine it would be quiet dramatic if the brakes were engaged at all times.

On the above photo the return from the hydro is Tee'd into the feed from the PS pump to the ps cooler...higher pressure which reduces outflow from the hydro boost. The return has to be teed into the hose coming from the ps cooler back to the ps pump. Honestly this isn't all that clear in the online tutorials I read (although I certainly do appreciate that they were done). The easiest way to prevent this would be just to use the ps pump with the 2nd return inlet. But that's also unnecessary.

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.

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.

That could work too, I'm going to check ebay for one. But if rearranging the T fitting and splicing in after the cooler doesn't work, I'm going to pick up a hydroboost pump for $50 at the pick-a-part and see if that doesn't fix it.

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.

Interesting. So on the other side of the power steering cooler is lower pressure? Wish you had told me a couple of years ago :eyes:

The only thing is, I dont know why this problem manifested just now. You would think it would have started immediately. Maybe your PS cooler is plugged up.

I hope not. I'm overdue for an easy fix on this truck.

Lucas power steering tar + cold temps and the T probably created the perfect storm. The lucas is the only thing that changed and probably created just enough extra pressure.

Didn't have enough slack to connect the previously cut hose to the steering box, so I just switched the T so that the booster runs straight to the cooler. I plan to pick up some more 3/8" hose tomorrow and splice in after the cooler when I have a chance. Hopefully this provides a temporary fix.

Thanks for the help guys :cheers:

Welp, that didn't help anything. Hoping switching the T to the return line after the cooler works, otherwise I'm getting a new (junk yard) power steering pump.

Switching the T to the line between the cooler and reservoir, with the straight part of the T going from the hydroboost to the reservoir, seemed to have done the trick. No dragging at all and the pedal returns quickly when I let off the brakes.

I did this last night, so time will tell, but usually on cold starts (like this morning at 40*) it's the worst and I have to let it warm up a bit. But this morning, it was ready to go immediately.

Huge thanks for the help guys, I don't think I would have figured this out on my own :)

Wow!!!!! Just finished my hydroboost conversion (truck in sig) and was having this exact issue. I have a junk yard 2005 2500hd hydroboost and pedal and an autozone ps pump for a 2005 suburban. It comes with the factory low pressure return fitting for the hydroboost. Mine was the factory pump with 275k on it. Brakes were dragging more and more a I drove it. Found this thread and did some research and it turned out I had connected the low pressure hydroboost return into the high pressure ps cooler return on the pump. As the brakes were used the hose would fill up with fluid and back up into the hydroboost causing the brakes to bind up. Swapped the returns around and they now work great. The best mod I have done to my truck. No more white knuckle panic stops! Brakes are much more predictable.

Great thread! Bump to the top! It saved my day!

Old thread but good info here.
I am having the dragging problem with my 2002 rcsb hydro boost conversion. I did the swap a bunch of years ago and the first time I had the dragging problem I spaced the master out with washers.
The dragging is back.
the truck has been sitting for about 4 weeks. Key on engine off the brakes apply enough I can’t roll the truck in neutral. I loosened the master and can then roll it. Tightened it back up and it seemed that after 15-20 min it wasn’t able to roll again.
I never started the engine so the drain issue seems like it’s not the problem.
I unhooked the pedal from the booster and it has over an inch of upward travel so I don’t think the rod is too long.
Any other ideas? Is it possible the abs unit can cause this?
I haven’t had a lot of time to troubleshoot yet but any brainstorming ahead of time will be helpful.
I don’t remember where the booster came from. Are there any models that have too long of an output rod?
it is mounted upside down but I went many years without trouble and I’m not aware of what changes could have caused the problem to come back.

I assume you have the lines run correctly... like in this picture:

https://cimg3.ibsrv.net/gimg/www.per...34ec1a2954.png

If so, you might consider a Y connector instead of a T.

Why do you have the Hydrobooster mounted upside down? I wonder if that might make the rod just a hair too long, or have some binding?

Have you checked your brake pedal return spring to make sure it is mounted correctly and able to hold the pedal up?

yeah its run right.
turns out i kind of jumped to conclusions and the brake system is ok on the truck.