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#1 Dissolving rust on fresh air vent inlets

Posted: Wed Jun 17, 2026 7:31 pm
by Busterwebb
Decided to refurbish the fresh air vents on my series 3. Removed them (needs to be done with care as the suspension arms are attached to the frame with the same bolts), drilled out the pop rivets, removed the springs and stand-off posts for the control flaps, stripped off the paint, then before de-rusting:

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Then rather than use an expensive de-rusting agent, I used a mixture of 1Litre hot water to 100g of citric acid and 63g of sodium bicarbonate. Soak for a few hours and agitate occasionally with a wire brush:

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Then paint, re-assemble and pop rivet

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Cheaper than buying new ones! Hope the de-rusting tip helps a few people.

#2 Re: Dissolving rust on fresh air vent inlets

Posted: Wed Jun 17, 2026 9:47 pm
by John37
Have you tried electrolytic rust removal? I've not used it myself but it comes highly recommended on other forums.

#3 Re: Dissolving rust on fresh air vent inlets

Posted: Wed Jun 17, 2026 10:10 pm
by Busterwebb
Not tried electrolytic rust removal. Will try that next time. Thanks for the tip.