Corroded/rusted and rounded screw removal advice

Processing61 · 06-26-2021, 12:43 AM

Hi guys, slightly different kind of post but about something I’m sure you are all familiar with working on older BMWs and cars in general:

What would be the best ways to remove these screws? I’m currently taking off the rear undertray and a couple of the screws have corroded/rusted and can’t get any purchase on them and there is a couple that are rounded. They have an 8mm hex head and screw into u clips on the other side.

Has anyone found a particular way which is best?

Thanks

Phil325i · 06-26-2021, 02:09 AM

As I recall these are only self tapper retainers. Very low torque. I would soak them in releasing agent then use a small Mole grip to turn. Buy some replacements before you remove them.

therealdb1 · 06-26-2021, 04:28 PM

If you cannot get pliers / mole grips to turn them I would drill the head off and once the undertray has dropped you should have enough screw left for pliers to turn out. They should not be tight it is only a fibre tray by the looks of it.
Any replacement self tapper with a suitable washer to spread the load will do when you refit the tray.

jwilalex · 06-26-2021, 04:58 PM

Another alternative is to get a small 6” hack saw and cut a flat head screw driver slot into the head. Also a good squirt of penetrating oil as previously mentioned.

Processing61 · 06-27-2021, 12:54 AM

Thanks guys, will give all these a try

06-26-2021, 12:43 AM	#1
Processing61 First Lieutenant 61 Rep 346 Posts Drives: BMW E91 325D Join Date: May 2019 Location: U.K. iTrader: (0)	Corroded/rusted and rounded screw removal advice Hi guys, slightly different kind of post but about something I’m sure you are all familiar with working on older BMWs and cars in general: What would be the best ways to remove these screws? I’m currently taking off the rear undertray and a couple of the screws have corroded/rusted and can’t get any purchase on them and there is a couple that are rounded. They have an 8mm hex head and screw into u clips on the other side. Has anyone found a particular way which is best? Thanks Attached Images
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06-26-2021, 02:09 AM	#2
Phil325i Brigadier General 616 Rep 3,194 Posts Drives: E92 325i MSport Coupe Join Date: Apr 2012 Location: UK South East iTrader: (1) Garage List 2009 BMW 325i Coupe [6.00]	As I recall these are only self tapper retainers. Very low torque. I would soak them in releasing agent then use a small Mole grip to turn. Buy some replacements before you remove them. __________________ E92 pre-LCI 325i - Ohlins R&T; H&R spacers; M3 strut brace; Swift thrust sheets; 3 x chassis braces; diff brace; N53 V-brace; 034 subframe inserts; BMS clutch stop; BMS CDV; RE g/box mounts; Delrin shift bushes; Saikoumichi OCC; Cyba scoops; BMW Perf Exhaust; HEL s/steel brake hoses; M3 rear spoiler; Recaro Sportster CSs; M3 white dash LEDs; LED Angels; LED side repeaters; BMW Perf black grille; CSL reps; SSDD carbon diffuser; Monster Wrap black roof/clear front
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06-26-2021, 04:28 PM	#3
therealdb1 Lieutenant 106 Rep 576 Posts Drives: Graphite E93 335i Join Date: Aug 2017 Location: Norfolk UK iTrader: (0)	If you cannot get pliers / mole grips to turn them I would drill the head off and once the undertray has dropped you should have enough screw left for pliers to turn out. They should not be tight it is only a fibre tray by the looks of it. Any replacement self tapper with a suitable washer to spread the load will do when you refit the tray.
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06-26-2021, 04:58 PM	#4
jwilalex Private First Class 31 Rep 125 Posts Drives: E90 318i LCI SE Business Edn Join Date: Jan 2016 Location: Glasgow iTrader: (0)	Another alternative is to get a small 6” hack saw and cut a flat head screw driver slot into the head. Also a good squirt of penetrating oil as previously mentioned.
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06-27-2021, 12:54 AM	#5
Processing61 First Lieutenant 61 Rep 346 Posts Drives: BMW E91 325D Join Date: May 2019 Location: U.K. iTrader: (0)	Thanks guys, will give all these a try
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