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E21 (1975 - 1983)

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Old 07-11-2014, 06:13 AM
PeterCS PeterCS is offline
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Location: Oakville, ON, Canada
Join Date: Jan 2014
Posts: 3
Mein Auto: 82 315 Baur
Expansion Tank from Gas Tank

Do I need this expansion tank?

What does it do?


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Old 01-19-2015, 06:04 PM
Jtbgonesailing Jtbgonesailing is offline
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Location: Atlantic Beach, Fl
Join Date: Nov 2014
Posts: 482
Mein Auto: 05 530i & 81 320i
Do you need it, yes. The 2 fuel cells will fill to full capacity during a fill up. Once filled and the fuel cap replaced, on a hot day the fuel in the fuel cells will expand. Thus the expansion tank will hold this fuel that has overflowed the fuel cells. Absent the expansion tank, the fuel would expand into the Charcole canister, under the battery pedestal at the left front of the engine bay.
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Old 01-20-2015, 12:02 AM
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BMWFatherFigure BMWFatherFigure is offline
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Location: Perth, Western Australia
Join Date: Aug 2012
Posts: 4,106
Mein Auto: E23;E32;E34;E38;R50;R55
Also part of the pulse reducing system. Put it this way - BMW spent $M in R&D. Do you honestly think they would leave in an unnecessary part that does not require maintaining (no ongoing income for them)? The Defence rests, your Honour.
Good - Fast - Cheap: Pick any two.
3 x E32 735iL (Alpine White, Glacier Blue & Kashmir Beige); 2 X E38 735iL (Oxford Green & Alpine White); E53 X5 4.4i (Pearl Beige); R50 Cooper; R55 Cooper Clubman (Both Pure Silver).
E38 Parts Car
E21 318i; E23 735i; E30 318i; E32 735iL; E34 535i; E38 730iL; E53 4.4i
I've just changed my wiper blades and now my reverse lights don't work. Should I change my fuel pump relay?
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