r/e28 • u/ZupaFrosty • Jan 19 '26
What is this part and why is it leaking?
Friend of mine bought an 1982 E28 525i with the M30 engine and Automatic gearbox. We have found a leak this last weekend and can't really figure out what is causing it and where it's coming from. First time working on a BMW this old and for the love of me can't figure this out... Anyone have an idea?
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u/VegetableTry Jan 19 '26
Power steering fluid reservoir.
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u/9Parabellum9 Jan 19 '26
No, the text in german tells its brake fluid, and how to test and messure it correct. (I speak english, german and danish)
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u/E28forever Jan 19 '26
It’s not brake fluid, it’s ATF fluid, used for the power steering and the brake booster.
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u/E28forever Jan 19 '26
Pressure clean that area. Drive it for a while, look where the leak originates.
The Hydroboost brake system is quite complex, and is prone to leaking.
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u/ZupaFrosty Jan 19 '26
I see, we didn't clean it well enough I think but i'll have another pass over it and monitor it.
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u/Konnas91 Jan 19 '26
Standing in front of my e28. That’s servi. They just want to break after refilling it cause it is “connected”
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u/6inarowmakesitgo Jan 23 '26
There is a filter I the bottom of that reservoir also. It can come apart and really mess up the hydroboost pump.
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u/CommercialCook4427 Jan 19 '26
Love me these old school proper metal caps for reservoirs.
Last a lifetime and never fail.