[Basir]

Hey guys,

I've been having this loud power steering noise for about a year and a half now:

It actually sounds a lot louder in person and its a lot louder outside the car. It does not sound good at all. It only comes when the engine/fluids warm up. It does not come when fully cold.

About 1 year ago, I figured a power steering fluid flush would do it, so I had it done at my indy BMW shop at the same time as some other things. It remained exactly the same.

I also got the belt and tensioner changed just recently in case that was it. No change.

Now just yesterday, I went to the BMW dealer for something else, and the tech heard the sound and checked the fluid, he said there was ATF in there (its red, and the Pentosin is green) and that is why its making that noise.

Now my question is, if its actually regular ATF in there, how bad is it? Its been in there for about a year. How much should I yell at my indy shop? Obviously I will get them to flush it again with the proper stuff, but has any damage been done?

Thanks

[Three_thirty_I]

ATF will ruin the seals and I think some of the hosing on this system which is designed to run CHF-11S as you know. I don't know if it is as simple as flushing the system, and what extent the damage may be, if there is actual damage. But the indy BMW shop needs to get a hiding for not paying attention to the CHF-11S sticker that is on the top of the reservoirs cap for the PS fluid.

Hopefully more people will reply.

[Efthreeoh]

So BMW has used the same PS reservoir cap for the past 30 years or so. When they switched to CHF-11 they merely just put a green sticker on the cap rather than manufacture a new cap with CHF-11 embossed in the plastic. The label can easily come off. Check if yours did. Under the label it indicates to use ATF, which is possibly why ATF was used in you car. I'd completely drain and flush the system. Refill with Pentosin CHF-11 and see what happens.

[kkasson]

I never completely figured it out but I think some of the early E90s came with ATF as the factory fill? So I don't think that anything in the system is incompatible with ATF, the issue is just that the fluids aren't compatible with each other. So I agree, just flush it out and see what happens.

[Three_thirty_I]

Originally Posted by kkasson

I never completely figured it out but I think some of the early E90s came with ATF as the factory fill? So I don't think that anything in the system is incompatible with ATF, the issue is just that the fluids aren't compatible with each other. So I agree, just flush it out and see what happens.

I might be horribly wrong saying this, but my E90 is a 2005 model since South Africa got them back then already, and mine uses CHF-11S, not ATF. The earlier E46 used ATF and had the same reservoirs and cap. I would just flush and see how it goes.

[Efthreeoh]

All E90s use CHF-11S.