hydro-boost

[duderhimer]

I have a 1974 Ford Bronco 302 w/power steering. About a year ago I installed a hydro-boost from a 1995 Chevy Astro van which has worked very well since installed. The only problem I"m fighting is air getting in the power steering system. After driving for approx 30 minutes, the hydro-boost starts applying the brakes uncommanded. I've removed the pitman arm and master cylinder in order to bleed the complete system several times, without much success. After fully bleeding the system, approx. a week later air seems to find it's way back into the system. Has anyone ran into this problem or heard of it happening to others? Could the 1974 power steering pump (original equipment) be overworked for this application? Could the hydro-boost be faulty (It was a rebuilt unit from local parts store)? Your help would be greatly appreciated.

Ken

 

[S_bolt19]

The HB system can get air in it, but it will circulate back to the pump in a matter of seconds where it will just lose itself at the top of the pump. The only thing that I can think of is that you might have a leak somewhere in a supply line. Like to the PS unit or from the PS to the HB (or vice versa, I don't remember off the top of my head which is first in line). Those are the only two pressurized lines. The other lines are all low pressure return lines and it wouldn't matter. You might also have a bad seal in the HB unit itself. As for the 74 pump being overworked, it's a possibility there as well. It might not be able to keep up with the demand for both pressurized units and could be failing. Hard to determine. I would start out by jacking the front tires off the ground and while it's running, turn the steering wheel from lock to lock a dozen or so times. Leave everything hooked up (pitman arm, etc.) so that it goes through its regular duty cycle. Then I would get to looking at the pressurized lines. Take some soapy water and pour on the lines, if you see anything, bubbles or suction, then you know where the problem is. If the lines test out OK, you could go in either direction, the pump or the HB unit. If you are worried about the original pump being the culprit, it might be time to upgrade to the saganaw/canned ham pump upgrade. Your other alternative is to take the HB off and take it back and get another unit if it is still under warranty. Which might not be a bad idea anyway. I have had mine on for quite a while and have never had an air problem, the only thing that I have ever had go wrong is my pump is starting to die right now because it's 30+ years old. When I do go to replace it, I am going with the dual return saganaw pump so that I don't have to worry about having that dual "T" return in the system.