Foaming power steering fluid?

[325e '87]

My son’s ‘87 is foaming the steering fluid and it’s noisy. I know there must be air contaminating the fluid somehow but I don’t know which component in the system is most likely to be the problem.

Also, if air is getting sucked into the fluid I would think that there would be fluid leaking from the problem area. The system doesn’t leak any fluid onto the ground, so I’m having a hard time locating the source of the problem. The only fluid that has leaked out is from the reservoir cap when the fluid is all foamed up.

So, what’s the most likely component that is failing?

[tomstin]

Did it start all of a sudden? Or has the problem been developing for some time? Any chance someone put something else other than power steering fluid / auto trans fluid? I would drain it the best you can and refill with know good fluid.

[325e '87]

Did it start all of a sudden? Or has the problem been developing for some time? Any chance someone put something else other than power steering fluid / auto trans fluid? I would drain it the best you can and refill with know good fluid.

Happened suddenly. We had his intake manifold off to clean stuff up, re seal and clean injectors, etc...once we had everything back together and coolant filled and bled, took a drive and the noisy pump started when he got home and backed in the garage.

Thanks for the reply

[jeffnhiscars]

there is a bypass tube (plastic I think) and theres a vent in the cap. Either being plugged might cause this. The reservoir also has a filter thats a 100k replacement item although it can easily be flushed with the reservoir off.

I'd start with a system flush and some fresh atf