My power steering pump overflows while driving. The fluid isn't aerated. The pump is quiet. The truck steers fine. Every time I bleed it I disconnect the drag link from the pitman arm. I have tried bleeding with the front of the truck as high as I dare and with the truck on all four tires. The suspension linkages, bushings, and kingpins were replaced last year when I replaced the tires and got an alignment. Nothing is binding. I don't feel any resistance in the steering wheel.
1. This all started because I bent the return line female fitting in the gearbox while changing my motor mounts. It immediately leaked a small about of fluid. I tightened the fitting, it stopped leaking but in the weeks after the steering felt off.
2. I thought the pump was failing. I rebuilt the pump with new seals and slipper springs. After the rebuild the pump was a little noisy and I couldn't bleed the air out of the system. I thought I pinched the o-ring on the pump reservoir housing.
3. I replaced the pump with a new "quiet" pump from Lares, replaced both hoses, and added a magnetic filter to the return line. It was quiet but did not fix the bleed problem. Checking the hose connections I noticed the female return fitting on the pump was bent. I think I bent it when I was doing the motor mounts.
5. I replaced the gearbox with a new one from Red Head. I bleed the system according to Redhead's instructions: cycling the wheel 15-20 times, let it sit overnight, then cycle it again 7-10 times. This did not correct the problem. The gearbox makes whistling sounds left of center and will not bleed. I get a near constant stream of tiny bubbles that seem to get worse the longer I bleed. There is no fluid leakage from the gearbox, pump, or hoses. I get extreme fluctuation in fluid level when cycling the box - so much so that I have to put a funnel in the pump fill tube and it goes from the bottom of the funnel to the top each time.
6. I use copper flare gaskets to ensure no leak at fittings. This does not fix the problem.
7. Redhead tells me it is trapped air. They have me remove both hoses and cycle the box (to clear a blockage?). Both power and return fitting spit fluid and suck air as the box is cycled. They have me reconnect the power line first, turn the wheel, a few times, then reconnect the return line, and turn the wheel a few times. This initially appears to fix the problem. At first I get big bubbles with no sounds from the gearbox. However, within about three turns it starts whistling and I get a constant stream of small bubbles.
8. I buy another new set of hoses and don't install filter on the return line. I independently vacuum test the pump/ hoses and gearbox/hoses. They each held 25 inches of vacuum.
9. I “bench bled” the gearbox using vacuum to pull fluid from a container into the power line and out from the return line until there was no signs of air. I reconnected the hoses to the pump and bled the system with only a few large bubbles. Entire system holds steady 20+ inches overnight.
10. Start the engine, pump is quiet, no fluctuations in fluid level, and no bubbles/aeration. Driving around the block I heard slight cavitation/chatter when turning left of center. Bled the system again. Box made the whistling noise again, I get constant bubbles, and the fluid levels fluctuate.
9. Redhead says whistling noise is my steering bearings. Removed rag joint and cycled the box manually. The noise is coming from the box.
10. The bleed instructions for the pump are different from the bleed instructions for the Red Head gear. The pump instructions say to disable the ignition and crank the engine while cycling the steering box at least four times. I "bench bleed" the gearbox again then do the pump bleed procedure. No bubbles but the fluid level fluctuates. Go for a test drive with the fluid at the bottom of the funnel right at the top of the fill tube. When I get home the fluid has risen to the top of the funnel. No foam. No bubbles. Fluid is clear. Let it sit for a few hours and the fluid level drops about half way down the funnel. Drive it again and when I get home it is back up near the top of the funnel.
I've been doing this for three weeks now. I can drive the truck with a funnel in the pump fill tube allowing the fluid level to fluctuate without overflowing. But if I remove the funnel, the pump overflows, I get low fluid levels causing foaming, the pump to get noisy, and the steering wheel to get stiff.
I've been driving around with this darn funnel hoping that some trapped air will bubble out and the fluid levels will stop fluctuating. Just never seems to happen. Makes it so that I don't trust driving the truck far from home. Anyone ever seen anything like this?
Power Steering Pump Overflow
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