E39 power steering problem?

[Spudooli 18]

If I push my E39 540i hard round corners, the steering gets heavier and heavier the faster round the corner I go. Basically what happens is that if I go fast enough round a corner then you'd need to be stronger man than me at some point to put in any more steering correction.

I can even induce this virtually no steering assistance at a give way intersection if I accelerate hard enough. I first noticed this on the Desert Road at Christmas round one of those 35km/h corners.

Is this speed controlled or steering angle power assist reduction completely normal or do you think my power steering pump just can't keep up?

I never feel like I've pushed the car past what its capable of. Or maybe my noodle arms just need to spend less time on a computer.

[M5V8 337]

This doesn't sound right.

E39's have speed sensitive power steering. It's fully active at low speeds and diminishes as the car increases in speed.

It has nothing to do with cornering or G force.

I'd say you need to get it checked.

firstly could be as easy as a slipping or loose belt. The correct tension needs to be applied to the belt to stop slip, & the belt needs to be in good nick also.

Look for leaks. How is the fluid level? has it dropped? any fluids on the floor where you regularly park?

[Spudooli 18]

For the sake of completeness, this problem resolved itself in Monday morning rush hour with the fan belt coming off just as I got onto the Auckland Harbour Bridge (of course).

There was no way in hell I was stopping on the bridge, but as I got to the top the temperature gauge got well into the red bit. Drove it off at Shelly Beach road off ramp, stopped as soon as I could and called a tow truck.

A bolt on the power steering pump had backed out, allowing the pump to twist. I'm assuming that under load the pump twisted, loosening the belt which caused the pump to stop providing steering assistance.

Anyways, a secondhand replacement pump has been installed and all is well, aside from the fact I've had to top up the coolant 4 times since getting the car back.

[Eagle 1662]

aside from the fact I've had to top up the coolant 4 times since getting the car back.

Sounds like its gone from a minor problem into a major

[Allanw 1071]

Oooof!

That's not good! For the gauge to get into the red, the engine has probably gotten to well over 115C (the OBC is usually set to gong when the coolant gets to 125C - WAY too hot!).

I'd get that coolant problem checked before it gets more major too

(As a side note, there was a guy up here with a 540i who had it diagnosed as needing a cam chain tensioner just a few weeks back. He decided to save up some dollars to get it done........ a few days later - CRUNCH clatter clatter etc. 32 bent valves etc. BIG billl coming for htat dude!)