Power Steering curiosity...

[Gary - K7GLD]

Last evening, after returning from a drive with the new truck, I left it outside the garage so I could more easily unload some stuff - and when finished, let the truck coast partially into the garage so I could vacuum the carpet. I turned on the key to unlock the steering wheel, and tho' it naturally steered hard with the engine off, I was able to coast and place it inside where I wanted it as I did the vacuum bit.



THEN, later, I wanted to back it outta the garage for some other chores - and was surprised to see a pretty decent puddle of oil at where the front of the engine had been, and a significant path of oil out to the fron of the garage, where it abruptly ceased.



A close check showed that the oil was from the power steering pump/reservoir - and when I then started the engine and turned the wheels back and forth, everything seems just fine...



I've done the "coast" into the garage bit before, both with this truck, and MANY times with the old truck and other vehicles equipped with power steering - and NEVER lost power steering fluid before - anyone else seen this, or have a clue as to why it happened?

 

[Alan Reagan]

Don't know why it blew the oil but I'll tell you what happened to me doing the coast thing. I coasted out of my garage one day and put on brakes. Did the maintenance I wanted to do and fired it up. When I put on brakes I got a heck of a moan out of the steering gear/pump area. It's like it got air in the line (I know that sound from changing the steering gear box). The pedal was mushy for a few seconds and the steering gear was vibrating. Then it stopped and has never done it again. I didn't lose any fluid, tho.

 

[CPFF]

P/S Pump

Sounds like the same problems I just went thru with my P/S pump. Everything worked fine until I changed from vaccume to hydro-boost brakes. The capacity of the reservoir in the Saginaw P/S pump is next to nothing. When the motor is off and you use the brakes, you discharge fluid from the accumulater,the reservoir is so small it has no where to go but out the vent. Turning the steering wheel with the motor off does the same thing.

Once you burp some oil out, the pump cavitates (sucks wind),foams up the oil and if it continues, kills the pump.

I cured mine by putting on a quart+ remote reservoir.

CPFF

 

[illflem]

Here's what's happening. Most all power steering gears are a pump as well as a directional valve, this allows you to safely steer in the event of engine shutdown. When your PS pump isn't turning it blocks flow, it becomes a valve. When you crank the steering wheel with the engine off you are pumping fluid from the system and returning it to the reservoir which can only overflow since the non-turning pump is blocking the normal circular flow. The pump isn't a 100% effective valve when off, it will allow the fluid to circulate if you turn the wheel slowly. Aside from not turning the wheel with the engine off CPFF's solution sounds good.