Back when I did my first engine clean-up, I converted the truck to hydro-boost brakes. Since then I have only put 1300 miles on the truck. As soon as I started driving the truck after the swap, I noticed a couple things. The first and most annoying was the new dual return power steering pump would howl when I stepped on the brakes, or turned the steering wheel. I exchanged the new pump and it seemed better for a while, but now the noise has returned. The steering and brakes feel fine, but when your trying to back into a parking spot at cruise night while holding the brakes and steering, the pump really gets groaning.

It has always had a problem with pushing fluid back out the reservoir cap, and always had frothy oil. Today, I ran it with the cap off the reservoir and noticed lots of bubbles (big bubbles) in the oil. There are no leaks anywhere, so I don't know where the air is coming from.

The whole system is plumbed with #6 AN fittings and hoses.

This is the only hydroboost system I've ever played with, so I'm looking for some ideas of what to check before I chuck the whole thing in the trash and go back to vacuum brakes....

 

I'd say there is air in the system and the pump impeller is cavitating.

My other guess is the pump pulley is too small and it is spinning too fast. Consider a larger pulley to slow down the pump?

 

Sounds like you have air getting in the system.
This could be from the suction side of the pump system.
After it sits for s couple of days with out starting it is there bubbles in the oil?
Start it and watch the oil. Does it get air bubbles in it right away? After you rev it up?
To trouble shoot a air leak on the suction side. Cap off the dipstick. Hole some how and put a low amount of air pressure to it. Start with 1-3 psi through a pressure regulator and watch for leaks.
Air bubbles after you rev it up. Sounds like you have a restriction on the return or suction side if the pump.
suction or return line should always be larger than the pressure side.
Is it the proper oil level when the engine is running?
With the hydro boost maybe sit needs to at the full mark with the engine running.
Does the hydro boost have a accumulator built into it?
This give you power brakes for several applications with the engine not running.
Hope this helps

 

The pulley is the same one that came off my original 1979 "power steering only" power steering pump. I assumed it would be the same size.........

All my hoses are #6 (3/8") Should my return lines be #8 (1/2")?

Does it matter which port each of the two return lines hooks up to on the reservoir. I have the one from the steering box hooked into the port that is kind of in the neck of the reservoir. I noticed the return oil coming out of it still has a fair amount of pressure?

Hopefully I'll be able to get out to the garage in the next few days to keep working on it.

 

What style of pump are you using ? What may work would be to add a separate reservoir just below the fill level of the pump, “T” the 2 return lines to 1 into the reservoir then to the pump.
I feel a very slight nudge in the steering wheel when turning and applying the brakes on my XL but I have a Modular engine with a separate reservoir with 1 line to the pump and the hydro boost/ steering box return are set up with a “T” fitting. I also am using the original power steering fin cooler that was original on my 67. I have had 0 issues with my set up. Are you using power steering fluid or transmission fluid?

 

All return lines should return the oil below the fluid level. This will keep the fluid from picking up air as it drops back to the reservoir level.
Example. Fill a bucket with a garden hose above the water level. Lots of air with the water.
Now fill the bucket with the end of the hose below the water level. No bubbles in the water.
I am not familiar with hydro boost systems but I work with hyd systems quite a bit.
i thought that hydro boost systems were in series. Pump to hydro boost to steering. The extra line if you have one is just for low pressure low flow leakage return?

 

What are you using for P/S fluid ?

 

I'm using regular ATF.

 

What is the system you installed off ? Is it Ford components pre 98-96. Cause prior to then Type F fluid was used as a P/S fluid in Ford vehicles. Some P/S bits react badly and do not operate properly on Mercon V ATF if they were spec'd for Type F. Type F also resists foaming more than Mercon V. That is in part why it stuck around for 20 years as a P/S fluid after it was last used as an ATF .

 

ATF contains anti-foaming agents but if cavitating enough then all bets are off.

 

Try to purge the ATF from the whole system and re fill with Power Steering fluid.
Also like mentioned above fluid must return below the level.

 

I got the Hydroboost unit from an 04 F250 Diesel at the wrecking yard.

 

Here's a diagram from a Power Stroke set up. The line shown as green should enter the pump above the oil level. Also, there should be something in the pressure line from the pump to regulate that pressure.

 

Thanks for the picture! Mt return lines are hooked up the opposite way, with the Hydroboost unit returning to the bottom of the reservoir, and the steering box returning to the top of the reservoir. I also don't have a cooler installed.....
OK.......so I have a couple things to work on.

 

I swapped my return lines so that they are now hooked up as shown in the above diagram. I then re-hooked up the pressure hoses to the hydroboost and steering box. As soon as I started the truck, I noticed there was no more hum from the power steering pump at idle. The fluid in the reservoir used to be very turbulent, but is now smooth as glass as the pump runs. I think this as a result of correctly hooking up the return lines. With the front wheels in the air, I slowly turned the wheels from lock to lock. When I got to each lock, I'd hold it there and the pump would whine very faintly like any vehicle would. I also noticed a few bubbles as I held it against the lock, but these eventually stopped too.

Then I tried pressing the brake, while turning the wheels (still up in the air) and no noise from the pump! I'm going to put it back down on the ground and try it, but I'm hopeful this was a simple fix.