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Homepage. This page: How to free-up rusted fastenings
Looking after a car
rusted nuts
Once the split pins are removed these corroded shackles should come apart with some TLC
rusty wheelnut
This rear wheel nut on my old Dodge lorry hasn't been off since the early 1950s
corrosion on a cylinder head stud
The head on this 6 cylinder sidevalve engine shouldn't be too bad to remove as the corrosion is only minor & the threads don't look too bad
Old paint and rust will need cleaning off before attempting to remove these hub nuts

Removing very rusty nuts and bolts.

Please note: All advice on oldclassiccar is just that, advice. If you have any doubts about your own abilities when it comes to working on your car, I'd recommend getting hands-on advice & help from someone who is used to working on old cars. I can't accept any responsibility for mistakes you make, or things being damaged as a result of your working on a car after having read articles on this site. If in doubt, check with a marque expert first. You can find contacts for owners clubs in the club directory (see homepage).

Tackling these corroded fastenings...

One of the most frustrating problems that the budding classic fan is likely to come up against is freeing up rusted nuts or bolts. You have shiny new parts to fit on the car, have the right tools to do the job, and a limited time to get the job done, then a stubborn nut comes along to spoil the party. On this page are some tips on how to free up a rusty nut or bolt. The end result with most of these approaches is a damaged fastening that can't be re-used, so its worth checking that you have a suitable replacement nut or bolt to hand.

Before doing anything drastic, clean up the bolt head and surrounding area as much as possible. If nothing else it'll be cleaner to work with, and will allow penetrating fluid to do its job better. A wire brush, either hand or powered by a drill, will do the job in no time. If its a nut that your having trouble with, make sure any exposed thread is cleaned up. The wire brush usually does the trick.

Next, make sure you are using the correct size spanner, anything else will probably slip under load and likely as not, damage both you and the bolt head at the same time. If you plan to replace with new fastenings, and the old one is already rounded off and scrap, you could try tapping on a slightly undersize socket on to it, but that should only be a last resort as you run a big risk of slipping.

Any of the following suggestions may do the trick and free up a corroded bolt head or recalcitrant nut, although a combination of several tricks is usually required...

A tap on the side of a nut with a suitably sized hammer (don't go mad, a tap should do) may be enough to free things up. Watch you don't damage the flats on the bolt head as you'll be wanting to get a decent spanner on it soon. Wherever possible use a ring spanner or socket of the correct size, open ended spanners can easily slip when loaded up.

If a rusty nut still won't shift after some deft tapping, I reckon its worth heating up the offending article. Apply heat from a blowlamp onto the side of the nut, the idea being to heat it up enough for it to expand slightly and free itself from the threads on the stud. Take great care when waving a flame around a car as there are many combustible items around, especially under the bonnet. Leaking carburettors or fuel lines dont make for good bedfellows with a naked flame, so go carefully! After a few minutes of heating the nut will be HOT so remember that when you dive back in with the spanners. If you can't safely get in with a lamp (for example under the bonnet) you have have to remove whatever component the offending fastener is attached to (if possible). So for example if a thermostat housing is proving to be a pig to remove, it'll be safer to whip the head off and heat up the bolt or nut away from all combustible materials in the car.

Odd as it may sound, one way to successfully loosen a nut is to tighten it slightly, the aim with all these approaches is to break the joint that has formed between the nut and the thread its attached to. It may then slacken off with no further aggro.

By now you're temper may be getting short so if you can, douse the threads or bolt head with a penetrating fluid and leave it for a while. The wire brushing you did earlier will let the fluid seep down the threads better than if you'd left all the crud in place. Some deep corners of the engine bay are often difficult to get at with a decent size spanner. If you need some more leverage, but space is tight, you can sometimes join two spanners together to give extra leverage. The handle of a small trolley jack can also double up as a spanner extension to increase your powers of persuasion.

If the threads are majorly rusty, and the nut is coming off but under protest, take it slow and wind the nut on and off as you go, gradually winding further and further off from the thread. Oil or penetrating fluid on the grotty threads will help things along no end.

If the nut still isn't playing ball, your final option is probably the nut splitter. These need a bit of room to work, but can be effective. The nut will be scrap afterwards, so make sure you have a suitable replacement before mutilating the old one. These work by driving a sharp cutting edge into one flat of the nut, activated by you winding a threaded bolt that forms part of the nut splitter. Only go as far as you have to, go to far and you risk damaging the thread of the stud. If you've not got a splitter, a sharp chisel can do a comparable job. A stuck bolt can sometimes be freed using a chisel, if you drive the chisel in to one of the flats of the head at an angle. Doing this can quickly damage the head of the bolt enough to make fitting a spanner back on impossible (you can sometimes file things back if needs be), so I'd only do this if really pushed.

Most of these hints apply to nuts and to bolts. If a bolt is really proving to be a problem (some have very shallow heads and round off in no time), one option if you're handy at welding is to weld another nut on to the head of the bolt, and use that to swing on with a spanner - but only try this if you're welding is top notch and you can join the two up perfectly. A splatterly bobble of weld tacking the two together probably won' t be enough.

Freeing up any rusty fastening usually involves a lot of grunting and bad language. Levering hard to free up this type of fastening can be dangerous if the spanner slips, so at all times remember to stand in such a way that you won't launch forward into the parts you're working on should something slip. Otherwise a bruised face and teeth on the floor can easily result.

I've always found that a combination of heating, tapping, penetrating fluid (eg WD40 or Duck Oil), swearing and an assortment of decent spanners are required to fight these stubborn blighters. Of course if the thing had been assembled with a little care in the first place, the corroded-on fastening may not have materialised in the first place. Whenever assembling something I put a light dab of grease (usually copper grease) on the thread before winding the nut on (same goes for a fresh bolt before installation). This means that you'll have an excellent chance of getting the bu**er off again in future. In fact copper grease can be a god-send, especially where ferrous steel bolts pass through an aluminium housing such as a thermostat housing. Steel and aluminium react quite quickly and can make removing the bolt afterwards a nightmare, but a smidge of grease on the bolt usually avoids this problem.

As always, If you're not confident in what you're doing, I'd urge you to get advice from a trusted mechanic before venturing under the bonnet of your classic.

I also recommend that you have a look at the factory issued manual or handbook for your car before starting work, in case there are any peculiarities specific to your car that need to be taken into account when working on it.

Go back to the looking after your car section of oldclassiccar.co.uk

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