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Can power steering fluid level fluctuate with temperature

I had PS pump changed, and PS fluid flushed 4 months ago. I notice that PS fluid level has gone above max line in the container when the car is cold. Can the PS fluid level go up during summer? I live in North East so we’re in summer alright, and I’m not sure if the mechanic overfilled the PS fluid when it was flushed, or it has expanded with temperature. It’s also looking unclear and dirty so another mechanic is advising another PS fluid flushing only 4 months later.

You don’t mention the vehicle you’re talking about.

So? It’s anybody’s guess.


Simple answer…all fluids expand as they get hot.

Volume expansion coef for oil is about 0.0007 /K
That means for a 40ºC temperature change, the volume will change by about 0.03 or 3%.

How much that will change the level at the check point depends on the geometry.

Your local shop has a turkey-baster looking gadget they can use to draw some of that fluid out in a jiffy, to bring it down to below the max line. It was probably just over-filled a little on the last service. The level on mine does go up and down a little depending on how recently I drove the car, it’s the highest just after driving usually, which is when the fluid would be the warmest.

Why should the OP pay a shop for something they can do their selves?

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The only problem with overfilling the PS reservoir is the possibility of overflowing. Leaking fluid can cause the belt to slip or even cause a fire. How far above MAX is the fluid? And more important how far below the top is it? And the most likely time that an overfilled reservoir leaks is when the wheel is turned from side to side while the engine is off.

But a turkey baster is a quick and easy way to remove excess fluid.

Yes, but after you use it, buy your wife a new one.

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