BMW E39 power steering: heavy steering, whine and fluid
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What fluid goes in the E39 power steering?
In cold conditions the correct fluid is a CHF type, for example Pentosin CHF11S, and the reservoir cap says CHF only. Aftermarket fluids may not work, so it is best to choose the original. Different fluids should not be mixed.
E39 steering is heavy or the power steering whines – what can cause it?
The cause can be too little or old fluid, a leaking hose connection letting in air, or a pump that is not pumping. The fluid is changed and the leak is repaired. If there is enough fluid but the steering is stiff, also check the steering shaft universal joint and the rack connection.
Why does power steering fluid run onto the hoses?
The reservoir cap has an overflow hole that the fluid runs out of if the reservoir is overfilled. Leave the fill level halfway between the min and max marks.
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